Machine management

OpenShift Container Platform 4.6

Adding and maintaining cluster machines

Red Hat OpenShift Documentation Team

Abstract

This document provides instructions for managing the machines that make up an OpenShift Container Platform cluster. Some tasks make use of the enhanced automatic machine management functions of an OpenShift Container Platform cluster and some tasks are manual. Not all tasks that are described in this document are available in all installation types.

Chapter 1. Creating machine sets

1.1. Creating a machine set on AWS

You can create a different machine set to serve a specific purpose in your OpenShift Container Platform cluster on Amazon Web Services (AWS). For example, you might create infrastructure machine sets and related machines so that you can move supporting workloads to the new machines.

Important

This process is not applicable for clusters with manually provisioned machines. You can use the advanced machine management and scaling capabilities only in clusters where the Machine API is operational.

1.1.1. Machine API overview

The Machine API is a combination of primary resources that are based on the upstream Cluster API project and custom OpenShift Container Platform resources.

For OpenShift Container Platform 4.6 clusters, the Machine API performs all node host provisioning management actions after the cluster installation finishes. Because of this system, OpenShift Container Platform 4.6 offers an elastic, dynamic provisioning method on top of public or private cloud infrastructure.

The two primary resources are:

Machines
A fundamental unit that describes the host for a node. A machine has a providerSpec specification, which describes the types of compute nodes that are offered for different cloud platforms. For example, a machine type for a worker node on Amazon Web Services (AWS) might define a specific machine type and required metadata.
Machine sets
MachineSet resources are groups of machines. Machine sets are to machines as replica sets are to pods. If you need more machines or must scale them down, you change the replicas field on the machine set to meet your compute need.

The following custom resources add more capabilities to your cluster:

Machine autoscaler
The MachineAutoscaler resource automatically scales machines in a cloud. You can set the minimum and maximum scaling boundaries for nodes in a specified machine set, and the machine autoscaler maintains that range of nodes. The MachineAutoscaler object takes effect after a ClusterAutoscaler object exists. Both ClusterAutoscaler and MachineAutoscaler resources are made available by the ClusterAutoscalerOperator object.
Cluster autoscaler
This resource is based on the upstream cluster autoscaler project. In the OpenShift Container Platform implementation, it is integrated with the Machine API by extending the machine set API. You can set cluster-wide scaling limits for resources such as cores, nodes, memory, GPU, and so on. You can set the priority so that the cluster prioritizes pods so that new nodes are not brought online for less important pods. You can also set the scaling policy so that you can scale up nodes but not scale them down.
Machine health check
The MachineHealthCheck resource detects when a machine is unhealthy, deletes it, and, on supported platforms, makes a new machine.

In OpenShift Container Platform version 3.11, you could not roll out a multi-zone architecture easily because the cluster did not manage machine provisioning. Beginning with OpenShift Container Platform version 4.1, this process is easier. Each machine set is scoped to a single zone, so the installation program sends out machine sets across availability zones on your behalf. And then because your compute is dynamic, and in the face of a zone failure, you always have a zone for when you must rebalance your machines. The autoscaler provides best-effort balancing over the life of a cluster.

1.1.2. Sample YAML for a machine set custom resource on AWS

This sample YAML defines a machine set that runs in the us-east-1a Amazon Web Services (AWS) zone and creates nodes that are labeled with node-role.kubernetes.io/<role>: "".

In this sample, <infrastructure_id> is the infrastructure ID label that is based on the cluster ID that you set when you provisioned the cluster, and <role> is the node label to add.

apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id> 1
  name: <infrastructure_id>-<role>-<zone> 2
  namespace: openshift-machine-api
spec:
  replicas: 1
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id> 3
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role>-<zone> 4
  template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id> 5
        machine.openshift.io/cluster-api-machine-role: <role> 6
        machine.openshift.io/cluster-api-machine-type: <role> 7
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role>-<zone> 8
    spec:
      metadata:
        labels:
          node-role.kubernetes.io/<role>: "" 9
      providerSpec:
        value:
          ami:
            id: ami-046fe691f52a953f9 10
          apiVersion: awsproviderconfig.openshift.io/v1beta1
          blockDevices:
            - ebs:
                iops: 0
                volumeSize: 120
                volumeType: gp2
          credentialsSecret:
            name: aws-cloud-credentials
          deviceIndex: 0
          iamInstanceProfile:
            id: <infrastructure_id>-worker-profile 11
          instanceType: m4.large
          kind: AWSMachineProviderConfig
          placement:
            availabilityZone: us-east-1a
            region: us-east-1
          securityGroups:
            - filters:
                - name: tag:Name
                  values:
                    - <infrastructure_id>-worker-sg 12
          subnet:
            filters:
              - name: tag:Name
                values:
                  - <infrastructure_id>-private-us-east-1a 13
          tags:
            - name: kubernetes.io/cluster/<infrastructure_id> 14
              value: owned
          userDataSecret:
            name: worker-user-data
1 3 5 11 12 13 14
Specify the infrastructure ID that is based on the cluster ID that you set when you provisioned the cluster. If you have the OpenShift CLI installed, you can obtain the infrastructure ID by running the following command:
$ oc -n openshift-machine-api \
    -o jsonpath='{.spec.template.spec.providerSpec.value.ami.id}{"\n"}' \
    get machineset/<infrastructure_id>-worker-us-east-1a
2 4 8
Specify the infrastructure ID, node label, and zone.
6 7 9
Specify the node label to add.
10
Specify a valid Red Hat Enterprise Linux CoreOS (RHCOS) AMI for your AWS zone for your OpenShift Container Platform nodes.

1.1.3. Creating a machine set

In addition to the ones created by the installation program, you can create your own machine sets to dynamically manage the machine compute resources for specific workloads of your choice.

Prerequisites

  • Deploy an OpenShift Container Platform cluster.
  • Install the OpenShift CLI (oc).
  • Log in to oc as a user with cluster-admin permission.

Procedure

  1. Create a new YAML file that contains the machine set custom resource (CR) sample and is named <file_name>.yaml.

    Ensure that you set the <clusterID> and <role> parameter values.

    1. If you are not sure which value to set for a specific field, you can check an existing machine set from your cluster:

      $ oc get machinesets -n openshift-machine-api

      Example output

      NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
      agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1d   0         0                             55m
      agl030519-vplxk-worker-us-east-1e   0         0                             55m
      agl030519-vplxk-worker-us-east-1f   0         0                             55m

    2. Check values of a specific machine set:

      $ oc get machineset <machineset_name> -n \
           openshift-machine-api -o yaml

      Example output

      ...
      template:
          metadata:
            labels:
              machine.openshift.io/cluster-api-cluster: agl030519-vplxk 1
              machine.openshift.io/cluster-api-machine-role: worker 2
              machine.openshift.io/cluster-api-machine-type: worker
              machine.openshift.io/cluster-api-machineset: agl030519-vplxk-worker-us-east-1a

      1
      The cluster ID.
      2
      A default node label.
  2. Create the new MachineSet CR:

    $ oc create -f <file_name>.yaml
  3. View the list of machine sets:

    $ oc get machineset -n openshift-machine-api

    Example output

    NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
    agl030519-vplxk-infra-us-east-1a    1         1         1       1           11m
    agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1d   0         0                             55m
    agl030519-vplxk-worker-us-east-1e   0         0                             55m
    agl030519-vplxk-worker-us-east-1f   0         0                             55m

    When the new machine set is available, the DESIRED and CURRENT values match. If the machine set is not available, wait a few minutes and run the command again.

Next steps

If you need machine sets in other availability zones, repeat this process to create more machine sets.

1.1.4. Machine sets that deploy machines as Spot Instances

You can save on costs by creating a machine set running on AWS that deploys machines as non-guaranteed Spot Instances. Spot Instances utilize unused AWS EC2 capacity and are less expensive than On-Demand Instances. You can use Spot Instances for workloads that can tolerate interruptions, such as batch or stateless, horizontally scalable workloads.

Important

It is strongly recommended that control plane machines are not created on Spot Instances due to the increased likelihood of the instance being terminated. Manual intervention is required to replace a terminated control plane node.

AWS EC2 can terminate a Spot Instance at any time. AWS gives a two-minute warning to the user when an interruption occurs. OpenShift Container Platform begins to remove the workloads from the affected instances when AWS issues the termination warning.

Interruptions can occur when using Spot Instances for the following reasons:

  • The instance price exceeds your maximum price
  • The demand for Spot Instances increases
  • The supply of Spot Instances decreases

When AWS terminates an instance, a termination handler running on the Spot Instance node deletes the machine resource. To satisfy the machine set replicas quantity, the machine set creates a machine that requests a Spot Instance.

1.1.5. Creating Spot Instances by using machine sets

You can launch a Spot Instance on AWS by adding spotMarketOptions to your machine set YAML file.

Procedure

  • Add the following line under the providerSpec field:

    providerSpec:
      value:
        spotMarketOptions: {}

    You can optionally set the spotMarketOptions.maxPrice field to limit the cost of the Spot Instance. For example you can set maxPrice: '2.50'.

    If the maxPrice is set, this value is used as the hourly maximum spot price. If it is not set, the maximum price defaults to charge up to the On-Demand Instance price.

    Note

    It is strongly recommended to use the default On-Demand price as the maxPrice value and to not set the maximum price for Spot Instances.

1.2. Creating a machine set on Azure

You can create a different machine set to serve a specific purpose in your OpenShift Container Platform cluster on Microsoft Azure. For example, you might create infrastructure machine sets and related machines so that you can move supporting workloads to the new machines.

Important

This process is not applicable for clusters with manually provisioned machines. You can use the advanced machine management and scaling capabilities only in clusters where the Machine API is operational.

1.2.1. Machine API overview

The Machine API is a combination of primary resources that are based on the upstream Cluster API project and custom OpenShift Container Platform resources.

For OpenShift Container Platform 4.6 clusters, the Machine API performs all node host provisioning management actions after the cluster installation finishes. Because of this system, OpenShift Container Platform 4.6 offers an elastic, dynamic provisioning method on top of public or private cloud infrastructure.

The two primary resources are:

Machines
A fundamental unit that describes the host for a node. A machine has a providerSpec specification, which describes the types of compute nodes that are offered for different cloud platforms. For example, a machine type for a worker node on Amazon Web Services (AWS) might define a specific machine type and required metadata.
Machine sets
MachineSet resources are groups of machines. Machine sets are to machines as replica sets are to pods. If you need more machines or must scale them down, you change the replicas field on the machine set to meet your compute need.

The following custom resources add more capabilities to your cluster:

Machine autoscaler
The MachineAutoscaler resource automatically scales machines in a cloud. You can set the minimum and maximum scaling boundaries for nodes in a specified machine set, and the machine autoscaler maintains that range of nodes. The MachineAutoscaler object takes effect after a ClusterAutoscaler object exists. Both ClusterAutoscaler and MachineAutoscaler resources are made available by the ClusterAutoscalerOperator object.
Cluster autoscaler
This resource is based on the upstream cluster autoscaler project. In the OpenShift Container Platform implementation, it is integrated with the Machine API by extending the machine set API. You can set cluster-wide scaling limits for resources such as cores, nodes, memory, GPU, and so on. You can set the priority so that the cluster prioritizes pods so that new nodes are not brought online for less important pods. You can also set the scaling policy so that you can scale up nodes but not scale them down.
Machine health check
The MachineHealthCheck resource detects when a machine is unhealthy, deletes it, and, on supported platforms, makes a new machine.

In OpenShift Container Platform version 3.11, you could not roll out a multi-zone architecture easily because the cluster did not manage machine provisioning. Beginning with OpenShift Container Platform version 4.1, this process is easier. Each machine set is scoped to a single zone, so the installation program sends out machine sets across availability zones on your behalf. And then because your compute is dynamic, and in the face of a zone failure, you always have a zone for when you must rebalance your machines. The autoscaler provides best-effort balancing over the life of a cluster.

1.2.2. Sample YAML for a machine set custom resource on Azure

This sample YAML defines a machine set that runs in the 1 Microsoft Azure zone in the centralus region and creates nodes that are labeled with node-role.kubernetes.io/<role>: "".

In this sample, <infrastructure_id> is the infrastructure ID label that is based on the cluster ID that you set when you provisioned the cluster, and <role> is the node label to add.

apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id> 1
    machine.openshift.io/cluster-api-machine-role: <role> 2
    machine.openshift.io/cluster-api-machine-type: <role> 3
  name: <infrastructure_id>-<role>-<region> 4
  namespace: openshift-machine-api
spec:
  replicas: 1
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id> 5
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role>-<region> 6
  template:
    metadata:
      creationTimestamp: null
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id> 7
        machine.openshift.io/cluster-api-machine-role: <role> 8
        machine.openshift.io/cluster-api-machine-type: <role> 9
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role>-<region> 10
    spec:
      metadata:
        creationTimestamp: null
        labels:
          node-role.kubernetes.io/<role>: "" 11
      providerSpec:
        value:
          apiVersion: azureproviderconfig.openshift.io/v1beta1
          credentialsSecret:
            name: azure-cloud-credentials
            namespace: openshift-machine-api
          image:
            offer: ""
            publisher: ""
            resourceID: /resourceGroups/<infrastructure_id>-rg/providers/Microsoft.Compute/images/<infrastructure_id> 12
            sku: ""
            version: ""
          internalLoadBalancer: ""
          kind: AzureMachineProviderSpec
          location: centralus
          managedIdentity: <infrastructure_id>-identity 13
          metadata:
            creationTimestamp: null
          natRule: null
          networkResourceGroup: ""
          osDisk:
            diskSizeGB: 128
            managedDisk:
              storageAccountType: Premium_LRS
            osType: Linux
          publicIP: false
          publicLoadBalancer: ""
          resourceGroup: <infrastructure_id>-rg 14
          sshPrivateKey: ""
          sshPublicKey: ""
          subnet: <infrastructure_id>-<role>-subnet 15 16
          userDataSecret:
            name: worker-user-data 17
          vmSize: qeci-22538-vnet
          vnet: <infrastructure_id>-vnet 18
          zone: "1" 19
1 5 7 12 13 14 15 18
Specify the infrastructure ID that is based on the cluster ID that you set when you provisioned the cluster. If you have the OpenShift CLI installed, you can obtain the infrastructure ID by running the following command:
$ oc get -o jsonpath='{.status.infrastructureName}{"\n"}' infrastructure cluster

You can obtain the subnet by running the following command:

$  oc -n openshift-machine-api \
    -o jsonpath='{.spec.template.spec.providerSpec.value.subnet}{"\n"}' \
    get machineset/<infrastructure_id>-worker-centralus1

You can obtain the vnet by running the following command:

$  oc -n openshift-machine-api \
    -o jsonpath='{.spec.template.spec.providerSpec.value.vnet}{"\n"}' \
    get machineset/<infrastructure_id>-worker-centralus1
2 3 8 9 11 16 17
Specify the node label to add.
4 6 10
Specify the infrastructure ID, node label, and region.
19
Specify the zone within your region to place machines on. Be sure that your region supports the zone that you specify.

1.2.3. Creating a machine set

In addition to the ones created by the installation program, you can create your own machine sets to dynamically manage the machine compute resources for specific workloads of your choice.

Prerequisites

  • Deploy an OpenShift Container Platform cluster.
  • Install the OpenShift CLI (oc).
  • Log in to oc as a user with cluster-admin permission.

Procedure

  1. Create a new YAML file that contains the machine set custom resource (CR) sample and is named <file_name>.yaml.

    Ensure that you set the <clusterID> and <role> parameter values.

    1. If you are not sure which value to set for a specific field, you can check an existing machine set from your cluster:

      $ oc get machinesets -n openshift-machine-api

      Example output

      NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
      agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1d   0         0                             55m
      agl030519-vplxk-worker-us-east-1e   0         0                             55m
      agl030519-vplxk-worker-us-east-1f   0         0                             55m

    2. Check values of a specific machine set:

      $ oc get machineset <machineset_name> -n \
           openshift-machine-api -o yaml

      Example output

      ...
      template:
          metadata:
            labels:
              machine.openshift.io/cluster-api-cluster: agl030519-vplxk 1
              machine.openshift.io/cluster-api-machine-role: worker 2
              machine.openshift.io/cluster-api-machine-type: worker
              machine.openshift.io/cluster-api-machineset: agl030519-vplxk-worker-us-east-1a

      1
      The cluster ID.
      2
      A default node label.
  2. Create the new MachineSet CR:

    $ oc create -f <file_name>.yaml
  3. View the list of machine sets:

    $ oc get machineset -n openshift-machine-api

    Example output

    NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
    agl030519-vplxk-infra-us-east-1a    1         1         1       1           11m
    agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1d   0         0                             55m
    agl030519-vplxk-worker-us-east-1e   0         0                             55m
    agl030519-vplxk-worker-us-east-1f   0         0                             55m

    When the new machine set is available, the DESIRED and CURRENT values match. If the machine set is not available, wait a few minutes and run the command again.

1.2.4. Machine sets that deploy machines as Spot Instances

1.2.5. Machine sets that deploy machines as Spot VMs

You can save on costs by creating a machine set running on AWS that deploys machines as non-guaranteed Spot Instances. Spot Instances utilize unused AWS EC2 capacity and are less expensive than On-Demand Instances. You can use Spot Instances for workloads that can tolerate interruptions, such as batch or stateless, horizontally scalable workloads. You can save on costs by creating a machine set running on Azure that deploys machines as non-guaranteed Spot VMs. Spot VMs utilize unused Azure capacity and are less expensive than standard VMs. You can use Spot VMs for workloads that can tolerate interruptions, such as batch or stateless, horizontally scalable workloads.

Important

It is strongly recommended that control plane machines are not created on Spot Instances Spot VMs due to the increased likelihood of the instance being terminated. Manual intervention is required to replace a terminated control plane node.

AWS EC2 can terminate a Spot Instance at any time. AWS gives a two-minute warning to the user when an interruption occurs. OpenShift Container Platform begins to remove the workloads from the affected instances when AWS issues the termination warning.

Interruptions can occur when using Spot Instances for the following reasons:

  • The instance price exceeds your maximum price
  • The demand for Spot Instances increases
  • The supply of Spot Instances decreases

When AWS terminates an instance, a termination handler running on the Spot Instance node deletes the machine resource. To satisfy the machine set replicas quantity, the machine set creates a machine that requests a Spot Instance. Azure can terminate a Spot VM at any time. Azure gives a 30-second warning to the user when an interruption occurs. OpenShift Container Platform begins to remove the workloads from the affected instances when Azure issues the termination warning.

Interruptions can occur when using Spot VMs for the following reasons:

  • The instance price exceeds your maximum price
  • The supply of Spot VMs decreases
  • Azure needs capacity back

When Azure terminates an instance, a termination handler running on the Spot VM node deletes the machine resource. To satisfy the machine set replicas quantity, the machine set creates a machine that requests a Spot VM.

1.2.6. Creating Spot Instances by using machine sets

1.2.7. Creating Spot VMs by using machine sets

You can launch a Spot Instance on AWS by adding spotMarketOptions to your machine set YAML file. You can launch a Spot VM on Azure by adding spotVMOptions to your machine set YAML file.

Procedure

  • Add the following line under the providerSpec field:

    providerSpec:
      value:
        spotMarketOptions: {}

    You can optionally set the spotMarketOptions.maxPrice field to limit the cost of the Spot Instance. For example you can set maxPrice: '2.50'.

    If the maxPrice is set, this value is used as the hourly maximum spot price. If it is not set, the maximum price defaults to charge up to the On-Demand Instance price.

    Note

    It is strongly recommended to use the default On-Demand price as the maxPrice value and to not set the maximum price for Spot Instances.

providerSpec:
  value:
    spotVMOptions: {}

+ You can optionally set the spotVMOptions.maxPrice field to limit the cost of the Spot VM. For example you can set maxPrice: '0.98765'. If the maxPrice is set, this value is used as the hourly maximum spot price. If it is not set, the maximum price defaults to -1 and charges up to the standard VM price.

+ Azure caps Spot VM prices at the standard price. Azure will not evict an instance due to pricing if the instance is set with the default maxPrice. However, an instance can still be evicted due to capacity restrictions.

Note

It is strongly recommended to use the default standard VM price as the maxPrice value and to not set the maximum price for Spot VMs.

1.2.8. Enabling customer-managed encryption keys for a machine set

You can supply an encryption key to Azure to encrypt data on managed disks at rest. You can enable server-side encryption with customer-managed keys by using the Machine API.

An Azure Key Vault, a disk encryption set, and an encryption key are required to use a customer-managed key. The disk encryption set must preside in a resource group where the Cloud Credential Operator (CCO) has granted permissions. If not, an additional reader role is required to be granted on the disk encryption set.

Procedure

  • Configure the disk encryption set under the providerSpec field in your machine set YAML file. For example:

    ...
    providerSpec:
      value:
        ...
        osDisk:
          diskSizeGB: 128
          managedDisk:
            diskEncryptionSet:
              id: /subscriptions/<subscription_id>/resourceGroups/<resource_group_name>/providers/Microsoft.Compute/diskEncryptionSets/<disk_encryption_set_name>
            storageAccountType: Premium_LRS
    ...

Additional resources

1.3. Creating a machine set on GCP

You can create a different machine set to serve a specific purpose in your OpenShift Container Platform cluster on Google Cloud Platform (GCP). For example, you might create infrastructure machine sets and related machines so that you can move supporting workloads to the new machines.

Important

This process is not applicable for clusters with manually provisioned machines. You can use the advanced machine management and scaling capabilities only in clusters where the Machine API is operational.

1.3.1. Machine API overview

The Machine API is a combination of primary resources that are based on the upstream Cluster API project and custom OpenShift Container Platform resources.

For OpenShift Container Platform 4.6 clusters, the Machine API performs all node host provisioning management actions after the cluster installation finishes. Because of this system, OpenShift Container Platform 4.6 offers an elastic, dynamic provisioning method on top of public or private cloud infrastructure.

The two primary resources are:

Machines
A fundamental unit that describes the host for a node. A machine has a providerSpec specification, which describes the types of compute nodes that are offered for different cloud platforms. For example, a machine type for a worker node on Amazon Web Services (AWS) might define a specific machine type and required metadata.
Machine sets
MachineSet resources are groups of machines. Machine sets are to machines as replica sets are to pods. If you need more machines or must scale them down, you change the replicas field on the machine set to meet your compute need.

The following custom resources add more capabilities to your cluster:

Machine autoscaler
The MachineAutoscaler resource automatically scales machines in a cloud. You can set the minimum and maximum scaling boundaries for nodes in a specified machine set, and the machine autoscaler maintains that range of nodes. The MachineAutoscaler object takes effect after a ClusterAutoscaler object exists. Both ClusterAutoscaler and MachineAutoscaler resources are made available by the ClusterAutoscalerOperator object.
Cluster autoscaler
This resource is based on the upstream cluster autoscaler project. In the OpenShift Container Platform implementation, it is integrated with the Machine API by extending the machine set API. You can set cluster-wide scaling limits for resources such as cores, nodes, memory, GPU, and so on. You can set the priority so that the cluster prioritizes pods so that new nodes are not brought online for less important pods. You can also set the scaling policy so that you can scale up nodes but not scale them down.
Machine health check
The MachineHealthCheck resource detects when a machine is unhealthy, deletes it, and, on supported platforms, makes a new machine.

In OpenShift Container Platform version 3.11, you could not roll out a multi-zone architecture easily because the cluster did not manage machine provisioning. Beginning with OpenShift Container Platform version 4.1, this process is easier. Each machine set is scoped to a single zone, so the installation program sends out machine sets across availability zones on your behalf. And then because your compute is dynamic, and in the face of a zone failure, you always have a zone for when you must rebalance your machines. The autoscaler provides best-effort balancing over the life of a cluster.

1.3.2. Sample YAML for a machine set custom resource on GCP

This sample YAML defines a machine set that runs in Google Cloud Platform (GCP) and creates nodes that are labeled with node-role.kubernetes.io/<role>: "".

In this sample, <infrastructure_id> is the infrastructure ID label that is based on the cluster ID that you set when you provisioned the cluster, and <role> is the node label to add.

apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id> 1
  name: <infrastructure_id>-w-a 2
  namespace: openshift-machine-api
spec:
  replicas: 1
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id> 3
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-w-a 4
  template:
    metadata:
      creationTimestamp: null
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id> 5
        machine.openshift.io/cluster-api-machine-role: <role> 6
        machine.openshift.io/cluster-api-machine-type: <role> 7
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-w-a 8
    spec:
      metadata:
        labels:
          node-role.kubernetes.io/<role>: "" 9
      providerSpec:
        value:
          apiVersion: gcpprovider.openshift.io/v1beta1
          canIPForward: false
          credentialsSecret:
            name: gcp-cloud-credentials
          deletionProtection: false
          disks:
          - autoDelete: true
            boot: true
            image: <path_to_image> 10
            labels: null
            sizeGb: 128
            type: pd-ssd
          kind: GCPMachineProviderSpec
          machineType: n1-standard-4
          metadata:
            creationTimestamp: null
          networkInterfaces:
          - network: <infrastructure_id>-network 11
            subnetwork: <infrastructure_id>-worker-subnet 12
          projectID: <project_name> 13
          region: us-central1
          serviceAccounts:
          - email: <infrastructure_id>-w@<project_name>.iam.gserviceaccount.com 14 15
            scopes:
            - https://www.googleapis.com/auth/cloud-platform
          tags:
          - <infrastructure_id>-worker 16
          userDataSecret:
            name: worker-user-data
          zone: us-central1-a
1 2 3 4 5 8 11 12 14 16
Specify the infrastructure ID that is based on the cluster ID that you set when you provisioned the cluster. If you have the OpenShift CLI installed, you can obtain the infrastructure ID by running the following command:
$ oc get -o jsonpath='{.status.infrastructureName}{"\n"}' infrastructure cluster
6 7 9
Specify the node label to add.
10
Specify the path to the image that is used in current machine sets. If you have the OpenShift CLI installed, you can obtain the path to the image by running the following command:
$ oc -n openshift-machine-api \
    -o jsonpath='{.spec.template.spec.providerSpec.value.disks[0].image}{"\n"}' \
    get machineset/<infrastructure_id>-worker-a
13 15
Specify the name of the GCP project that you use for your cluster.

1.3.3. Creating a machine set

In addition to the ones created by the installation program, you can create your own machine sets to dynamically manage the machine compute resources for specific workloads of your choice.

Prerequisites

  • Deploy an OpenShift Container Platform cluster.
  • Install the OpenShift CLI (oc).
  • Log in to oc as a user with cluster-admin permission.

Procedure

  1. Create a new YAML file that contains the machine set custom resource (CR) sample and is named <file_name>.yaml.

    Ensure that you set the <clusterID> and <role> parameter values.

    1. If you are not sure which value to set for a specific field, you can check an existing machine set from your cluster:

      $ oc get machinesets -n openshift-machine-api

      Example output

      NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
      agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1d   0         0                             55m
      agl030519-vplxk-worker-us-east-1e   0         0                             55m
      agl030519-vplxk-worker-us-east-1f   0         0                             55m

    2. Check values of a specific machine set:

      $ oc get machineset <machineset_name> -n \
           openshift-machine-api -o yaml

      Example output

      ...
      template:
          metadata:
            labels:
              machine.openshift.io/cluster-api-cluster: agl030519-vplxk 1
              machine.openshift.io/cluster-api-machine-role: worker 2
              machine.openshift.io/cluster-api-machine-type: worker
              machine.openshift.io/cluster-api-machineset: agl030519-vplxk-worker-us-east-1a

      1
      The cluster ID.
      2
      A default node label.
  2. Create the new MachineSet CR:

    $ oc create -f <file_name>.yaml
  3. View the list of machine sets:

    $ oc get machineset -n openshift-machine-api

    Example output

    NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
    agl030519-vplxk-infra-us-east-1a    1         1         1       1           11m
    agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1d   0         0                             55m
    agl030519-vplxk-worker-us-east-1e   0         0                             55m
    agl030519-vplxk-worker-us-east-1f   0         0                             55m

    When the new machine set is available, the DESIRED and CURRENT values match. If the machine set is not available, wait a few minutes and run the command again.

1.3.4. Machine sets that deploy machines as Spot Instances

1.3.5. Machine sets that deploy machines as Spot VMs

1.3.6. Machine sets that deploy machines as preemptible VM instances

You can save on costs by creating a machine set running on AWS that deploys machines as non-guaranteed Spot Instances. Spot Instances utilize unused AWS EC2 capacity and are less expensive than On-Demand Instances. You can use Spot Instances for workloads that can tolerate interruptions, such as batch or stateless, horizontally scalable workloads. You can save on costs by creating a machine set running on Azure that deploys machines as non-guaranteed Spot VMs. Spot VMs utilize unused Azure capacity and are less expensive than standard VMs. You can use Spot VMs for workloads that can tolerate interruptions, such as batch or stateless, horizontally scalable workloads. You can save on costs by creating a machine set running on GCP that deploys machines as non-guaranteed preemptible VM instances. Preemptible VM instances utilize excess Compute Engine capacity and are less expensive than normal instances. You can use preemptible VM instances for workloads that can tolerate interruptions, such as batch or stateless, horizontally scalable workloads.

Important

It is strongly recommended that control plane machines are not created on Spot Instances Spot VMs preemptible VM instances due to the increased likelihood of the instance being terminated. Manual intervention is required to replace a terminated control plane node.

AWS EC2 can terminate a Spot Instance at any time. AWS gives a two-minute warning to the user when an interruption occurs. OpenShift Container Platform begins to remove the workloads from the affected instances when AWS issues the termination warning.

Interruptions can occur when using Spot Instances for the following reasons:

  • The instance price exceeds your maximum price
  • The demand for Spot Instances increases
  • The supply of Spot Instances decreases

When AWS terminates an instance, a termination handler running on the Spot Instance node deletes the machine resource. To satisfy the machine set replicas quantity, the machine set creates a machine that requests a Spot Instance. Azure can terminate a Spot VM at any time. Azure gives a 30-second warning to the user when an interruption occurs. OpenShift Container Platform begins to remove the workloads from the affected instances when Azure issues the termination warning.

Interruptions can occur when using Spot VMs for the following reasons:

  • The instance price exceeds your maximum price
  • The supply of Spot VMs decreases
  • Azure needs capacity back

When Azure terminates an instance, a termination handler running on the Spot VM node deletes the machine resource. To satisfy the machine set replicas quantity, the machine set creates a machine that requests a Spot VM. GCP Compute Engine can terminate a preemptible VM instance at any time. Compute Engine sends a preemption notice to the user indicating that an interruption will occur in 30 seconds. OpenShift Container Platform begins to remove the workloads from the affected instances when Compute Engine issues the preemption notice. An ACPI G3 Mechanical Off signal is sent to the operating system after 30 seconds if the instance is not stopped. The preemptible VM instance is then transitioned to a TERMINATED state by Compute Engine.

Interruptions can occur when using preemptible VM instances for the following reasons:

  • There is a system or maintenance event
  • The supply of preemptible VM instances decreases
  • The instance reaches the end of the allotted 24-hour period for preemptible VM instances

When GCP terminates an instance, a termination handler running on the preemptible VM instance node deletes the machine resource. To satisfy the machine set replicas quantity, the machine set creates a machine that requests a preemptible VM instance.

1.3.7. Creating Spot Instances by using machine sets

1.3.8. Creating Spot VMs by using machine sets

1.3.9. Creating preemptible VM instances by using machine sets

You can launch a Spot Instance on AWS by adding spotMarketOptions to your machine set YAML file. You can launch a Spot VM on Azure by adding spotVMOptions to your machine set YAML file. You can launch a preemptible VM instance on GCP by adding preemptible to your machine set YAML file.

Procedure

  • Add the following line under the providerSpec field:

    providerSpec:
      value:
        spotMarketOptions: {}

    You can optionally set the spotMarketOptions.maxPrice field to limit the cost of the Spot Instance. For example you can set maxPrice: '2.50'.

    If the maxPrice is set, this value is used as the hourly maximum spot price. If it is not set, the maximum price defaults to charge up to the On-Demand Instance price.

    Note

    It is strongly recommended to use the default On-Demand price as the maxPrice value and to not set the maximum price for Spot Instances.

providerSpec:
  value:
    spotVMOptions: {}

+ You can optionally set the spotVMOptions.maxPrice field to limit the cost of the Spot VM. For example you can set maxPrice: '0.98765'. If the maxPrice is set, this value is used as the hourly maximum spot price. If it is not set, the maximum price defaults to -1 and charges up to the standard VM price.

+ Azure caps Spot VM prices at the standard price. Azure will not evict an instance due to pricing if the instance is set with the default maxPrice. However, an instance can still be evicted due to capacity restrictions.

Note

It is strongly recommended to use the default standard VM price as the maxPrice value and to not set the maximum price for Spot VMs.

providerSpec:
  value:
    preemptible: true

+ If preemptible is set to true, the machine is labelled as an interruptable-instance after the instance is launched.

1.4. Creating a machine set on OpenStack

You can create a different machine set to serve a specific purpose in your OpenShift Container Platform cluster on Red Hat OpenStack Platform (RHOSP). For example, you might create infrastructure machine sets and related machines so that you can move supporting workloads to the new machines.

Important

This process is not applicable for clusters with manually provisioned machines. You can use the advanced machine management and scaling capabilities only in clusters where the Machine API is operational.

1.4.1. Machine API overview

The Machine API is a combination of primary resources that are based on the upstream Cluster API project and custom OpenShift Container Platform resources.

For OpenShift Container Platform 4.6 clusters, the Machine API performs all node host provisioning management actions after the cluster installation finishes. Because of this system, OpenShift Container Platform 4.6 offers an elastic, dynamic provisioning method on top of public or private cloud infrastructure.

The two primary resources are:

Machines
A fundamental unit that describes the host for a node. A machine has a providerSpec specification, which describes the types of compute nodes that are offered for different cloud platforms. For example, a machine type for a worker node on Amazon Web Services (AWS) might define a specific machine type and required metadata.
Machine sets
MachineSet resources are groups of machines. Machine sets are to machines as replica sets are to pods. If you need more machines or must scale them down, you change the replicas field on the machine set to meet your compute need.

The following custom resources add more capabilities to your cluster:

Machine autoscaler
The MachineAutoscaler resource automatically scales machines in a cloud. You can set the minimum and maximum scaling boundaries for nodes in a specified machine set, and the machine autoscaler maintains that range of nodes. The MachineAutoscaler object takes effect after a ClusterAutoscaler object exists. Both ClusterAutoscaler and MachineAutoscaler resources are made available by the ClusterAutoscalerOperator object.
Cluster autoscaler
This resource is based on the upstream cluster autoscaler project. In the OpenShift Container Platform implementation, it is integrated with the Machine API by extending the machine set API. You can set cluster-wide scaling limits for resources such as cores, nodes, memory, GPU, and so on. You can set the priority so that the cluster prioritizes pods so that new nodes are not brought online for less important pods. You can also set the scaling policy so that you can scale up nodes but not scale them down.
Machine health check
The MachineHealthCheck resource detects when a machine is unhealthy, deletes it, and, on supported platforms, makes a new machine.

In OpenShift Container Platform version 3.11, you could not roll out a multi-zone architecture easily because the cluster did not manage machine provisioning. Beginning with OpenShift Container Platform version 4.1, this process is easier. Each machine set is scoped to a single zone, so the installation program sends out machine sets across availability zones on your behalf. And then because your compute is dynamic, and in the face of a zone failure, you always have a zone for when you must rebalance your machines. The autoscaler provides best-effort balancing over the life of a cluster.

1.4.2. Sample YAML for a machine set custom resource on RHOSP

This sample YAML defines a machine set that runs on Red Hat OpenStack Platform (RHOSP) and creates nodes that are labeled with node-role.kubernetes.io/<role>: "".

In this sample, <infrastructure_id> is the infrastructure ID label that is based on the cluster ID that you set when you provisioned the cluster, and <role> is the node label to add.

apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id> 1
    machine.openshift.io/cluster-api-machine-role: <role> 2
    machine.openshift.io/cluster-api-machine-type: <role> 3
  name: <infrastructure_id>-<role> 4
  namespace: openshift-machine-api
spec:
  replicas: <number_of_replicas>
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id> 5
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role> 6
  template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id> 7
        machine.openshift.io/cluster-api-machine-role: <role> 8
        machine.openshift.io/cluster-api-machine-type: <role> 9
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role> 10
    spec:
      providerSpec:
        value:
          apiVersion: openstackproviderconfig.openshift.io/v1alpha1
          cloudName: openstack
          cloudsSecret:
            name: openstack-cloud-credentials
            namespace: openshift-machine-api
          flavor: <nova_flavor>
          image: <glance_image_name_or_location>
          serverGroupID: <optional_UUID_of_server_group> 11
          kind: OpenstackProviderSpec
          networks: 12
          - filter: {}
            subnets:
            - filter:
                name: <subnet_name>
                tags: openshiftClusterID=<infrastructure_id> 13
          primarySubnet: <rhosp_subnet_UUID> 14
          securityGroups:
          - filter: {}
            name: <infrastructure_id>-worker 15
          serverMetadata:
            Name: <infrastructure_id>-worker 16
            openshiftClusterID: <infrastructure_id> 17
          tags:
          - openshiftClusterID=<infrastructure_id> 18
          trunk: true
          userDataSecret:
            name: worker-user-data 19
          availabilityZone: <optional_openstack_availability_zone>
1 5 7 13 15 16 17 18
Specify the infrastructure ID that is based on the cluster ID that you set when you provisioned the cluster. If you have the OpenShift CLI installed, you can obtain the infrastructure ID by running the following command:
$ oc get -o jsonpath='{.status.infrastructureName}{"\n"}' infrastructure cluster
2 3 8 9 19
Specify the node label to add.
4 6 10
Specify the infrastructure ID and node label.
11
To set a server group policy for the MachineSet, enter the value that is returned from creating a server group. For most deployments, anti-affinity or soft-anti-affinity policies are recommended.
12
Required for deployments to multiple networks. To specify multiple networks, add another entry in the networks array. Also, you must include the network that is used as the primarySubnet value.
14
Specify the RHOSP subnet that you want the endpoints of nodes to be published on. Usually, this is the same subnet that is used as the value of machinesSubnet in the install-config.yaml file.

1.4.3. Creating a machine set

In addition to the ones created by the installation program, you can create your own machine sets to dynamically manage the machine compute resources for specific workloads of your choice.

Prerequisites

  • Deploy an OpenShift Container Platform cluster.
  • Install the OpenShift CLI (oc).
  • Log in to oc as a user with cluster-admin permission.

Procedure

  1. Create a new YAML file that contains the machine set custom resource (CR) sample and is named <file_name>.yaml.

    Ensure that you set the <clusterID> and <role> parameter values.

    1. If you are not sure which value to set for a specific field, you can check an existing machine set from your cluster:

      $ oc get machinesets -n openshift-machine-api

      Example output

      NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
      agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1d   0         0                             55m
      agl030519-vplxk-worker-us-east-1e   0         0                             55m
      agl030519-vplxk-worker-us-east-1f   0         0                             55m

    2. Check values of a specific machine set:

      $ oc get machineset <machineset_name> -n \
           openshift-machine-api -o yaml

      Example output

      ...
      template:
          metadata:
            labels:
              machine.openshift.io/cluster-api-cluster: agl030519-vplxk 1
              machine.openshift.io/cluster-api-machine-role: worker 2
              machine.openshift.io/cluster-api-machine-type: worker
              machine.openshift.io/cluster-api-machineset: agl030519-vplxk-worker-us-east-1a

      1
      The cluster ID.
      2
      A default node label.
  2. Create the new MachineSet CR:

    $ oc create -f <file_name>.yaml
  3. View the list of machine sets:

    $ oc get machineset -n openshift-machine-api

    Example output

    NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
    agl030519-vplxk-infra-us-east-1a    1         1         1       1           11m
    agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1d   0         0                             55m
    agl030519-vplxk-worker-us-east-1e   0         0                             55m
    agl030519-vplxk-worker-us-east-1f   0         0                             55m

    When the new machine set is available, the DESIRED and CURRENT values match. If the machine set is not available, wait a few minutes and run the command again.

1.5. Creating a machine set on RHV

You can create a different machine set to serve a specific purpose in your OpenShift Container Platform cluster on Red Hat Virtualization (RHV). For example, you might create infrastructure machine sets and related machines so that you can move supporting workloads to the new machines.

Important

This process is not applicable for clusters with manually provisioned machines. You can use the advanced machine management and scaling capabilities only in clusters where the Machine API is operational.

1.5.1. Machine API overview

The Machine API is a combination of primary resources that are based on the upstream Cluster API project and custom OpenShift Container Platform resources.

For OpenShift Container Platform 4.6 clusters, the Machine API performs all node host provisioning management actions after the cluster installation finishes. Because of this system, OpenShift Container Platform 4.6 offers an elastic, dynamic provisioning method on top of public or private cloud infrastructure.

The two primary resources are:

Machines
A fundamental unit that describes the host for a node. A machine has a providerSpec specification, which describes the types of compute nodes that are offered for different cloud platforms. For example, a machine type for a worker node on Amazon Web Services (AWS) might define a specific machine type and required metadata.
Machine sets
MachineSet resources are groups of machines. Machine sets are to machines as replica sets are to pods. If you need more machines or must scale them down, you change the replicas field on the machine set to meet your compute need.

The following custom resources add more capabilities to your cluster:

Machine autoscaler
The MachineAutoscaler resource automatically scales machines in a cloud. You can set the minimum and maximum scaling boundaries for nodes in a specified machine set, and the machine autoscaler maintains that range of nodes. The MachineAutoscaler object takes effect after a ClusterAutoscaler object exists. Both ClusterAutoscaler and MachineAutoscaler resources are made available by the ClusterAutoscalerOperator object.
Cluster autoscaler
This resource is based on the upstream cluster autoscaler project. In the OpenShift Container Platform implementation, it is integrated with the Machine API by extending the machine set API. You can set cluster-wide scaling limits for resources such as cores, nodes, memory, GPU, and so on. You can set the priority so that the cluster prioritizes pods so that new nodes are not brought online for less important pods. You can also set the scaling policy so that you can scale up nodes but not scale them down.
Machine health check
The MachineHealthCheck resource detects when a machine is unhealthy, deletes it, and, on supported platforms, makes a new machine.

In OpenShift Container Platform version 3.11, you could not roll out a multi-zone architecture easily because the cluster did not manage machine provisioning. Beginning with OpenShift Container Platform version 4.1, this process is easier. Each machine set is scoped to a single zone, so the installation program sends out machine sets across availability zones on your behalf. And then because your compute is dynamic, and in the face of a zone failure, you always have a zone for when you must rebalance your machines. The autoscaler provides best-effort balancing over the life of a cluster.

1.5.2. Sample YAML for a machine set custom resource on RHV

This sample YAML defines a machine set that runs on RHV and creates nodes that are labeled with node-role.kubernetes.io/<node_role>: "".

In this sample, <infrastructure_id> is the infrastructure ID label that is based on the cluster ID that you set when you provisioned the cluster, and <role> is the node label to add.

apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id> 1
    machine.openshift.io/cluster-api-machine-role: <role> 2
    machine.openshift.io/cluster-api-machine-type: <role> 3
  name: <infrastructure_id>-<role> 4
  namespace: openshift-machine-api
spec:
  replicas: <number_of_replicas> 5
  Selector: 6
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id> 7
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role> 8
  template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id> 9
        machine.openshift.io/cluster-api-machine-role: <role> 10
        machine.openshift.io/cluster-api-machine-type: <role> 11
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role> 12
    spec:
      metadata:
        labels:
          node-role.kubernetes.io/<role>: "" 13
      providerSpec:
        value:
          apiVersion: ovirtproviderconfig.machine.openshift.io/v1beta1
          cluster_id: <ovirt_cluster_id> 14
          template_name: <ovirt_template_name> 15
          instance_type_id: <instance_type_id> 16
          cpu: 17
            sockets: <number_of_sockets> 18
            cores: <number_of_cores> 19
            threads: <number_of_threads> 20
          memory_mb: <memory_size> 21
          os_disk: 22
            size_gb: <disk_size> 23
          network_interfaces: 24
            vnic_profile_id:  <vnic_profile_id> 25
          credentialsSecret:
            name: ovirt-credentials 26
          kind: OvirtMachineProviderSpec
          type: <workload_type> 27
          userDataSecret:
            name: worker-user-data
1 7 9
Specify the infrastructure ID that is based on the cluster ID that you set when you provisioned the cluster. If you have the OpenShift CLI (oc) installed, you can obtain the infrastructure ID by running the following command:
$ oc get -o jsonpath='{.status.infrastructureName}{"\n"}' infrastructure cluster
2 3 10 11 13
Specify the node label to add.
4 8 12
Specify the infrastructure ID and node label. These two strings together cannot be longer than 35 characters.
5
Specify the number of machines to create.
6
Selector for the machines.
14
Specify the UUID for the RHV cluster to which this VM instance belongs.
15
Specify the RHV VM template to use to create the machine.
16
Optional: Specify the VM instance type. If you include this parameter, you do not need to specify the hardware parameters of the VM including CPU and memory because this parameter overrides all hardware parameters.
17
Optional: The CPU field contains the CPU’s configuration, including sockets, cores, and threads.
18
Optional: Specify the number of sockets for a VM.
19
Optional: Specify the number of cores per socket.
20
Optional: Specify the number of threads per core.
21
Optional: Specify the size of a VM’s memory in MiB.
22
Optional: Root disk of the node.
23
Optional: Specify the size of the bootable disk in GiB.
24
Optional: List of the network interfaces of the VM. If you include this parameter, OpenShift Container Platform discards all network interfaces from the template and creates new ones.
25
Optional: Specify the vNIC profile ID.
26
Specify the name of the secret that holds the RHV credentials.
27
Optional: Specify the workload type for which the instance is optimized. This value affects the RHV VM parameter. Supported values: desktop, server, high_performance.
Note

Because RHV uses a template when creating a VM, if you do not specify a value for an optional parameter, RHV uses the value for that parameter that is specified in the template.

1.5.3. Creating a machine set

In addition to the ones created by the installation program, you can create your own machine sets to dynamically manage the machine compute resources for specific workloads of your choice.

Prerequisites

  • Deploy an OpenShift Container Platform cluster.
  • Install the OpenShift CLI (oc).
  • Log in to oc as a user with cluster-admin permission.

Procedure

  1. Create a new YAML file that contains the machine set custom resource (CR) sample and is named <file_name>.yaml.

    Ensure that you set the <clusterID> and <role> parameter values.

    1. If you are not sure which value to set for a specific field, you can check an existing machine set from your cluster:

      $ oc get machinesets -n openshift-machine-api

      Example output

      NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
      agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1d   0         0                             55m
      agl030519-vplxk-worker-us-east-1e   0         0                             55m
      agl030519-vplxk-worker-us-east-1f   0         0                             55m

    2. Check values of a specific machine set:

      $ oc get machineset <machineset_name> -n \
           openshift-machine-api -o yaml

      Example output

      ...
      template:
          metadata:
            labels:
              machine.openshift.io/cluster-api-cluster: agl030519-vplxk 1
              machine.openshift.io/cluster-api-machine-role: worker 2
              machine.openshift.io/cluster-api-machine-type: worker
              machine.openshift.io/cluster-api-machineset: agl030519-vplxk-worker-us-east-1a

      1
      The cluster ID.
      2
      A default node label.
  2. Create the new MachineSet CR:

    $ oc create -f <file_name>.yaml
  3. View the list of machine sets:

    $ oc get machineset -n openshift-machine-api

    Example output

    NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
    agl030519-vplxk-infra-us-east-1a    1         1         1       1           11m
    agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1d   0         0                             55m
    agl030519-vplxk-worker-us-east-1e   0         0                             55m
    agl030519-vplxk-worker-us-east-1f   0         0                             55m

    When the new machine set is available, the DESIRED and CURRENT values match. If the machine set is not available, wait a few minutes and run the command again.

1.6. Creating a machine set on vSphere

You can create a different machine set to serve a specific purpose in your OpenShift Container Platform cluster on VMware vSphere. For example, you might create infrastructure machine sets and related machines so that you can move supporting workloads to the new machines.

Important

This process is not applicable for clusters with manually provisioned machines. You can use the advanced machine management and scaling capabilities only in clusters where the Machine API is operational.

1.6.1. Machine API overview

The Machine API is a combination of primary resources that are based on the upstream Cluster API project and custom OpenShift Container Platform resources.

For OpenShift Container Platform 4.6 clusters, the Machine API performs all node host provisioning management actions after the cluster installation finishes. Because of this system, OpenShift Container Platform 4.6 offers an elastic, dynamic provisioning method on top of public or private cloud infrastructure.

The two primary resources are:

Machines
A fundamental unit that describes the host for a node. A machine has a providerSpec specification, which describes the types of compute nodes that are offered for different cloud platforms. For example, a machine type for a worker node on Amazon Web Services (AWS) might define a specific machine type and required metadata.
Machine sets
MachineSet resources are groups of machines. Machine sets are to machines as replica sets are to pods. If you need more machines or must scale them down, you change the replicas field on the machine set to meet your compute need.

The following custom resources add more capabilities to your cluster:

Machine autoscaler
The MachineAutoscaler resource automatically scales machines in a cloud. You can set the minimum and maximum scaling boundaries for nodes in a specified machine set, and the machine autoscaler maintains that range of nodes. The MachineAutoscaler object takes effect after a ClusterAutoscaler object exists. Both ClusterAutoscaler and MachineAutoscaler resources are made available by the ClusterAutoscalerOperator object.
Cluster autoscaler
This resource is based on the upstream cluster autoscaler project. In the OpenShift Container Platform implementation, it is integrated with the Machine API by extending the machine set API. You can set cluster-wide scaling limits for resources such as cores, nodes, memory, GPU, and so on. You can set the priority so that the cluster prioritizes pods so that new nodes are not brought online for less important pods. You can also set the scaling policy so that you can scale up nodes but not scale them down.
Machine health check
The MachineHealthCheck resource detects when a machine is unhealthy, deletes it, and, on supported platforms, makes a new machine.

In OpenShift Container Platform version 3.11, you could not roll out a multi-zone architecture easily because the cluster did not manage machine provisioning. Beginning with OpenShift Container Platform version 4.1, this process is easier. Each machine set is scoped to a single zone, so the installation program sends out machine sets across availability zones on your behalf. And then because your compute is dynamic, and in the face of a zone failure, you always have a zone for when you must rebalance your machines. The autoscaler provides best-effort balancing over the life of a cluster.

1.6.2. Sample YAML for a machine set custom resource on vSphere

This sample YAML defines a machine set that runs on VMware vSphere and creates nodes that are labeled with node-role.kubernetes.io/<role>: "".

In this sample, <infrastructure_id> is the infrastructure ID label that is based on the cluster ID that you set when you provisioned the cluster, and <role> is the node label to add.

apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  creationTimestamp: null
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id> 1
  name: <infrastructure_id>-<role> 2
  namespace: openshift-machine-api
spec:
  replicas: 1
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id> 3
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role> 4
  template:
    metadata:
      creationTimestamp: null
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id> 5
        machine.openshift.io/cluster-api-machine-role: <role> 6
        machine.openshift.io/cluster-api-machine-type: <role> 7
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role> 8
    spec:
      metadata:
        creationTimestamp: null
        labels:
          node-role.kubernetes.io/<role>: "" 9
      providerSpec:
        value:
          apiVersion: vsphereprovider.openshift.io/v1beta1
          credentialsSecret:
            name: vsphere-cloud-credentials
          diskGiB: 120
          kind: VSphereMachineProviderSpec
          memoryMiB: 8192
          metadata:
            creationTimestamp: null
          network:
            devices:
            - networkName: "<vm_network_name>" 10
          numCPUs: 4
          numCoresPerSocket: 1
          snapshot: ""
          template: <vm_template_name> 11
          userDataSecret:
            name: worker-user-data
          workspace:
            datacenter: <vcenter_datacenter_name> 12
            datastore: <vcenter_datastore_name> 13
            folder: <vcenter_vm_folder_path> 14
            resourcepool: <vsphere_resource_pool> 15
            server: <vcenter_server_ip> 16
1 3 5
Specify the infrastructure ID that is based on the cluster ID that you set when you provisioned the cluster. If you have the OpenShift CLI (oc) installed, you can obtain the infrastructure ID by running the following command:
$ oc get -o jsonpath='{.status.infrastructureName}{"\n"}' infrastructure cluster
2 4 8
Specify the infrastructure ID and node label.
6 7 9
Specify the node label to add.
10
Specify the vSphere VM network to deploy the machine set to.
11
Specify the vSphere VM clone of the template to use, such as user-5ddjd-rhcos.
Important

Do not specify the original VM template. The VM template must remain off and must be cloned for new RHCOS machines. Starting the VM template configures the VM template as a VM on the platform, which prevents it from being used as a template that machine sets can apply configurations to.

12
Specify the vCenter Datacenter to deploy the machine set on.
13
Specify the vCenter Datastore to deploy the machine set on.
14
Specify the path to the vSphere VM folder in vCenter, such as /dc1/vm/user-inst-5ddjd.
15
Specify the vSphere resource pool for your VMs.
16
Specify the vCenter server IP or fully qualified domain name.

1.6.3. Creating a machine set

In addition to the ones created by the installation program, you can create your own machine sets to dynamically manage the machine compute resources for specific workloads of your choice.

Prerequisites

  • Deploy an OpenShift Container Platform cluster.
  • Install the OpenShift CLI (oc).
  • Log in to oc as a user with cluster-admin permission.
  • Create a tag inside your vCenter instance based on the cluster API name. This tag is utilized by the machine set to associate the OpenShift Container Platform nodes to the provisioned virtual machines (VM). For directions on creating tags in vCenter, see the VMware documentation for vSphere Tags and Attributes.
  • Have the necessary permissions to deploy VMs in your vCenter instance and have the required access to the datastore specified.

Procedure

  1. Create a new YAML file that contains the machine set custom resource (CR) sample and is named <file_name>.yaml.

    Ensure that you set the <clusterID> and <role> parameter values.

    1. If you are not sure which value to set for a specific field, you can check an existing machine set from your cluster:

      $ oc get machinesets -n openshift-machine-api

      Example output

      NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
      agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1d   0         0                             55m
      agl030519-vplxk-worker-us-east-1e   0         0                             55m
      agl030519-vplxk-worker-us-east-1f   0         0                             55m

    2. Check values of a specific machine set:

      $ oc get machineset <machineset_name> -n \
           openshift-machine-api -o yaml

      Example output

      ...
      template:
          metadata:
            labels:
              machine.openshift.io/cluster-api-cluster: agl030519-vplxk 1
              machine.openshift.io/cluster-api-machine-role: worker 2
              machine.openshift.io/cluster-api-machine-type: worker
              machine.openshift.io/cluster-api-machineset: agl030519-vplxk-worker-us-east-1a

      1
      The cluster ID.
      2
      A default node label.
  2. Create the new MachineSet CR:

    $ oc create -f <file_name>.yaml
  3. View the list of machine sets:

    $ oc get machineset -n openshift-machine-api

    Example output

    NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
    agl030519-vplxk-infra-us-east-1a    1         1         1       1           11m
    agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1d   0         0                             55m
    agl030519-vplxk-worker-us-east-1e   0         0                             55m
    agl030519-vplxk-worker-us-east-1f   0         0                             55m

    When the new machine set is available, the DESIRED and CURRENT values match. If the machine set is not available, wait a few minutes and run the command again.

Chapter 2. Manually scaling a machine set

You can add or remove an instance of a machine in a machine set.

Note

If you need to modify aspects of a machine set outside of scaling, see Modifying a machine set.

2.1. Prerequisites

Important

This process is not applicable for clusters with manually provisioned machines. You can use the advanced machine management and scaling capabilities only in clusters where the Machine API is operational.

2.2. Scaling a machine set manually

To add or remove an instance of a machine in a machine set, you can manually scale the machine set.

This guidance is relevant to fully automated, installer-provisioned infrastructure installations. Customized, user-provisioned infrastructure installations do not have machine sets.

Prerequisites

  • Install an OpenShift Container Platform cluster and the oc command line.
  • Log in to oc as a user with cluster-admin permission.

Procedure

  1. View the machine sets that are in the cluster:

    $ oc get machinesets -n openshift-machine-api

    The machine sets are listed in the form of <clusterid>-worker-<aws-region-az>.

  2. Scale the machine set:

    $ oc scale --replicas=2 machineset <machineset> -n openshift-machine-api

    Or:

    $ oc edit machineset <machineset> -n openshift-machine-api

    You can scale the machine set up or down. It takes several minutes for the new machines to be available.

2.3. The machine set deletion policy

Random, Newest, and Oldest are the three supported deletion options. The default is Random, meaning that random machines are chosen and deleted when scaling machine sets down. The deletion policy can be set according to the use case by modifying the particular machine set:

spec:
  deletePolicy: <delete_policy>
  replicas: <desired_replica_count>

Specific machines can also be prioritized for deletion by adding the annotation machine.openshift.io/cluster-api-delete-machine to the machine of interest, regardless of the deletion policy.

Important

By default, the OpenShift Container Platform router pods are deployed on workers. Because the router is required to access some cluster resources, including the web console, do not scale the worker machine set to 0 unless you first relocate the router pods.

Note

Custom machine sets can be used for use cases requiring that services run on specific nodes and that those services are ignored by the controller when the worker machine sets are scaling down. This prevents service disruption.

Chapter 3. Modifying a machine set

You can make changes to a machine set, such as adding labels, changing the instance type, or changing block storage.

Note

If you need to scale a machine set without making other changes, see Manually scaling a machine set.

3.1. Modifying a machine set

To make changes to a machine set, edit the MachineSet YAML. Then, remove all machines associated with the machine set by deleting each machine or scaling down the machine set to 0 replicas. Then, scale the replicas back to the desired number. Changes you make to a machine set do not affect existing machines.

If you need to scale a machine set without making other changes, you do not need to delete the machines.

Note

By default, the OpenShift Container Platform router pods are deployed on workers. Because the router is required to access some cluster resources, including the web console, do not scale the worker machine set to 0 unless you first relocate the router pods.

Prerequisites

  • Install an OpenShift Container Platform cluster and the oc command line.
  • Log in to oc as a user with cluster-admin permission.

Procedure

  1. Edit the machine set:

    $ oc edit machineset <machineset> -n openshift-machine-api
  2. Scale down the machine set to 0:

    $ oc scale --replicas=0 machineset <machineset> -n openshift-machine-api

    Or:

    $ oc edit machineset <machineset> -n openshift-machine-api

    Wait for the machines to be removed.

  3. Scale up the machine set as needed:

    $ oc scale --replicas=2 machineset <machineset> -n openshift-machine-api

    Or:

    $ oc edit machineset <machineset> -n openshift-machine-api

    Wait for the machines to start. The new machines contain changes you made to the machine set.

Chapter 4. Deleting a machine

You can delete a specific machine.

4.1. Deleting a specific machine

You can delete a specific machine.

Prerequisites

  • Install an OpenShift Container Platform cluster.
  • Install the OpenShift CLI (oc).
  • Log into oc as a user with cluster-admin permission.

Procedure

  1. View the machines that are in the cluster and identify the one to delete:

    $ oc get machine -n openshift-machine-api

    The command output contains a list of machines in the <clusterid>-worker-<cloud_region> format.

  2. Delete the machine:

    $ oc delete machine <machine> -n openshift-machine-api
    Important

    By default, the machine controller tries to drain the node that is backed by the machine until it succeeds. In some situations, such as with a misconfigured pod disruption budget, the drain operation might not be able to succeed in preventing the machine from being deleted. You can skip draining the node by annotating "machine.openshift.io/exclude-node-draining" in a specific machine. If the machine being deleted belongs to a machine set, a new machine is immediately created to satisfy the specified number of replicas.

Chapter 5. Applying autoscaling to an OpenShift Container Platform cluster

Applying autoscaling to an OpenShift Container Platform cluster involves deploying a cluster autoscaler and then deploying machine autoscalers for each machine type in your cluster.

Important

You can configure the cluster autoscaler only in clusters where the machine API is operational.

5.1. About the cluster autoscaler

The cluster autoscaler adjusts the size of an OpenShift Container Platform cluster to meet its current deployment needs. It uses declarative, Kubernetes-style arguments to provide infrastructure management that does not rely on objects of a specific cloud provider. The cluster autoscaler has a cluster scope, and is not associated with a particular namespace.

The cluster autoscaler increases the size of the cluster when there are pods that failed to schedule on any of the current nodes due to insufficient resources or when another node is necessary to meet deployment needs. The cluster autoscaler does not increase the cluster resources beyond the limits that you specify.

Important

Ensure that the maxNodesTotal value in the ClusterAutoscaler resource definition that you create is large enough to account for the total possible number of machines in your cluster. This value must encompass the number of control plane machines and the possible number of compute machines that you might scale to.

The cluster autoscaler decreases the size of the cluster when some nodes are consistently not needed for a significant period, such as when it has low resource use and all of its important pods can fit on other nodes.

If the following types of pods are present on a node, the cluster autoscaler will not remove the node:

  • Pods with restrictive pod disruption budgets (PDBs).
  • Kube-system pods that do not run on the node by default.
  • Kube-system pods that do not have a PDB or have a PDB that is too restrictive.
  • Pods that are not backed by a controller object such as a deployment, replica set, or stateful set.
  • Pods with local storage.
  • Pods that cannot be moved elsewhere because of a lack of resources, incompatible node selectors or affinity, matching anti-affinity, and so on.
  • Unless they also have a "cluster-autoscaler.kubernetes.io/safe-to-evict": "true" annotation, pods that have a "cluster-autoscaler.kubernetes.io/safe-to-evict": "false" annotation.

If you configure the cluster autoscaler, additional usage restrictions apply:

  • Do not modify the nodes that are in autoscaled node groups directly. All nodes within the same node group have the same capacity and labels and run the same system pods.
  • Specify requests for your pods.
  • If you have to prevent pods from being deleted too quickly, configure appropriate PDBs.
  • Confirm that your cloud provider quota is large enough to support the maximum node pools that you configure.
  • Do not run additional node group autoscalers, especially the ones offered by your cloud provider.

The horizontal pod autoscaler (HPA) and the cluster autoscaler modify cluster resources in different ways. The HPA changes the deployment’s or replica set’s number of replicas based on the current CPU load. If the load increases, the HPA creates new replicas, regardless of the amount of resources available to the cluster. If there are not enough resources, the cluster autoscaler adds resources so that the HPA-created pods can run. If the load decreases, the HPA stops some replicas. If this action causes some nodes to be underutilized or completely empty, the cluster autoscaler deletes the unnecessary nodes.

The cluster autoscaler takes pod priorities into account. The Pod Priority and Preemption feature enables scheduling pods based on priorities if the cluster does not have enough resources, but the cluster autoscaler ensures that the cluster has resources to run all pods. To honor the intention of both features, the cluster autoscaler includes a priority cutoff function. You can use this cutoff to schedule "best-effort" pods, which do not cause the cluster autoscaler to increase resources but instead run only when spare resources are available.

Pods with priority lower than the cutoff value do not cause the cluster to scale up or prevent the cluster from scaling down. No new nodes are added to run the pods, and nodes running these pods might be deleted to free resources.

5.2. About the machine autoscaler

The machine autoscaler adjusts the number of Machines in the machine sets that you deploy in an OpenShift Container Platform cluster. You can scale both the default worker machine set and any other machine sets that you create. The machine autoscaler makes more Machines when the cluster runs out of resources to support more deployments. Any changes to the values in MachineAutoscaler resources, such as the minimum or maximum number of instances, are immediately applied to the machine set they target.

Important

You must deploy a machine autoscaler for the cluster autoscaler to scale your machines. The cluster autoscaler uses the annotations on machine sets that the machine autoscaler sets to determine the resources that it can scale. If you define a cluster autoscaler without also defining machine autoscalers, the cluster autoscaler will never scale your cluster.

5.3. Configuring the cluster autoscaler

First, deploy the cluster autoscaler to manage automatic resource scaling in your OpenShift Container Platform cluster.

Note

Because the cluster autoscaler is scoped to the entire cluster, you can make only one cluster autoscaler for the cluster.

5.3.1. ClusterAutoscaler resource definition

This ClusterAutoscaler resource definition shows the parameters and sample values for the cluster autoscaler.

apiVersion: "autoscaling.openshift.io/v1"
kind: "ClusterAutoscaler"
metadata:
  name: "default"
spec:
  podPriorityThreshold: -10 1
  resourceLimits:
    maxNodesTotal: 24 2
    cores:
      min: 8 3
      max: 128 4
    memory:
      min: 4 5
      max: 256 6
    gpus:
      - type: nvidia.com/gpu 7
        min: 0 8
        max: 16 9
      - type: amd.com/gpu 10
        min: 0 11
        max: 4 12
  scaleDown: 13
    enabled: true 14
    delayAfterAdd: 10m 15
    delayAfterDelete: 5m 16
    delayAfterFailure: 30s 17
    unneededTime: 5m 18
1
Specify the priority that a pod must exceed to cause the cluster autoscaler to deploy additional nodes. Enter a 32-bit integer value. The podPriorityThreshold value is compared to the value of the PriorityClass that you assign to each pod.
2
Specify the maximum number of nodes to deploy. This value is the total number of machines that are deployed in your cluster, not just the ones that the autoscaler controls. Ensure that this value is large enough to account for all of your control plane and compute machines and the total number of replicas that you specify in your MachineAutoscaler resources.
3
Specify the minimum number of cores to deploy in the cluster.
4
Specify the maximum number of cores to deploy in the cluster.
5
Specify the minimum amount of memory, in GiB, in the cluster.
6
Specify the maximum amount of memory, in GiB, in the cluster.
7 10
Optionally, specify the type of GPU node to deploy. Only nvidia.com/gpu and amd.com/gpu are valid types.
8 11
Specify the minimum number of GPUs to deploy in the cluster.
9 12
Specify the maximum number of GPUs to deploy in the cluster.
13
In this section, you can specify the period to wait for each action by using any valid ParseDuration interval, including ns, us, ms, s, m, and h.
14
Specify whether the cluster autoscaler can remove unnecessary nodes.
15
Optionally, specify the period to wait before deleting a node after a node has recently been added. If you do not specify a value, the default value of 10m is used.
16
Specify the period to wait before deleting a node after a node has recently been deleted. If you do not specify a value, the default value of 10s is used.
17
Specify the period to wait before deleting a node after a scale down failure occurred. If you do not specify a value, the default value of 3m is used.
18
Specify the period before an unnecessary node is eligible for deletion. If you do not specify a value, the default value of 10m is used.
Note

When performing a scaling operation, the cluster autoscaler remains within the ranges set in the ClusterAutoscaler resource definition, such as the minimum and maximum number of cores to deploy or the amount of memory in the cluster. However, the cluster autoscaler does not correct the current values in your cluster to be within those ranges.

5.3.2. Deploying the cluster autoscaler

To deploy the cluster autoscaler, you create an instance of the ClusterAutoscaler resource.

Procedure

  1. Create a YAML file for the ClusterAutoscaler resource that contains the customized resource definition.
  2. Create the resource in the cluster:

    $ oc create -f <filename>.yaml 1
    1
    <filename> is the name of the resource file that you customized.

5.4. Next steps

  • After you configure the cluster autoscaler, you must configure at least one machine autoscaler.

5.5. Configuring the machine autoscalers

After you deploy the cluster autoscaler, deploy MachineAutoscaler resources that reference the machine sets that are used to scale the cluster.

Important

You must deploy at least one MachineAutoscaler resource after you deploy the ClusterAutoscaler resource.

Note

You must configure separate resources for each machine set. Remember that machine sets are different in each region, so consider whether you want to enable machine scaling in multiple regions. The machine set that you scale must have at least one machine in it.

5.5.1. MachineAutoscaler resource definition

This MachineAutoscaler resource definition shows the parameters and sample values for the machine autoscaler.

apiVersion: "autoscaling.openshift.io/v1beta1"
kind: "MachineAutoscaler"
metadata:
  name: "worker-us-east-1a" 1
  namespace: "openshift-machine-api"
spec:
  minReplicas: 1 2
  maxReplicas: 12 3
  scaleTargetRef: 4
    apiVersion: machine.openshift.io/v1beta1
    kind: MachineSet 5
    name: worker-us-east-1a 6
1
Specify the machine autoscaler name. To make it easier to identify which machine set this machine autoscaler scales, specify or include the name of the machine set to scale. The machine set name takes the following form: <clusterid>-<machineset>-<aws-region-az>
2
Specify the minimum number machines of the specified type that must remain in the specified zone after the cluster autoscaler initiates cluster scaling. If running in AWS, GCP, or Azure, this value can be set to 0. For other providers, do not set this value to 0.
3
Specify the maximum number machines of the specified type that the cluster autoscaler can deploy in the specified AWS zone after it initiates cluster scaling. Ensure that the maxNodesTotal value in the ClusterAutoscaler resource definition is large enough to allow the machine autoscaler to deploy this number of machines.
4
In this section, provide values that describe the existing machine set to scale.
5
The kind parameter value is always MachineSet.
6
The name value must match the name of an existing machine set, as shown in the metadata.name parameter value.

5.5.2. Deploying the machine autoscaler

To deploy the machine autoscaler, you create an instance of the MachineAutoscaler resource.

Procedure

  1. Create a YAML file for the MachineAutoscaler resource that contains the customized resource definition.
  2. Create the resource in the cluster:

    $ oc create -f <filename>.yaml 1
    1
    <filename> is the name of the resource file that you customized.

5.6. Additional resources

Chapter 6. Creating infrastructure machine sets

Important

This process is not applicable for clusters with manually provisioned machines. You can use the advanced machine management and scaling capabilities only in clusters where the Machine API is operational.

You can create a machine set to host only infrastructure components. You apply specific Kubernetes labels to these machines and then update the infrastructure components to run on only those machines. These infrastructure nodes are not counted toward the total number of subscriptions that are required to run the environment.

Important

Unlike earlier versions of OpenShift Container Platform, you cannot move the infrastructure components to the control plane machines (also known as the master machines). To move the components, you must create a new machine set.

6.1. OpenShift Container Platform infrastructure components

The following infrastructure workloads do not incur OpenShift Container Platform worker subscriptions:

  • Kubernetes and OpenShift Container Platform control plane services that run on masters
  • The default router
  • The integrated container image registry
  • The cluster metrics collection, or monitoring service, including components for monitoring user-defined projects
  • Cluster aggregated logging
  • Service brokers
  • Red Hat Quay
  • Red Hat OpenShift Container Storage
  • Red Hat Advanced Cluster Manager

Any node that runs any other container, pod, or component is a worker node that your subscription must cover.

6.2. Creating infrastructure machine sets for production environments

In a production deployment, deploy at least three machine sets to hold infrastructure components. Both the logging aggregation solution and the service mesh deploy Elasticsearch, and Elasticsearch requires three instances that are installed on different nodes. For high availability, deploy these nodes to different availability zones. Since you need different machine sets for each availability zone, create at least three machine sets.

6.2.1. Creating machine sets for different clouds

Use the sample machine set for your cloud.

6.2.1.1. Sample YAML for a machine set custom resource on AWS

This sample YAML defines a machine set that runs in the us-east-1a Amazon Web Services (AWS) zone and creates nodes that are labeled with node-role.kubernetes.io/infra: "".

In this sample, <infrastructure_id> is the infrastructure ID label that is based on the cluster ID that you set when you provisioned the cluster, and <infra> is the node label to add.

apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id> 1
  name: <infrastructure_id>-infra-<zone> 2
  namespace: openshift-machine-api
spec:
  replicas: 1
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id> 3
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-infra-<zone> 4
  template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id> 5
        machine.openshift.io/cluster-api-machine-role: <infra> 6
        machine.openshift.io/cluster-api-machine-type: <infra> 7
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-infra-<zone> 8
    spec:
      metadata:
        labels:
          node-role.kubernetes.io/infra: "" 9
      taints: 10
        - key: node-role.kubernetes.io/infra
          effect: NoSchedule
      providerSpec:
        value:
          ami:
            id: ami-046fe691f52a953f9 11
          apiVersion: awsproviderconfig.openshift.io/v1beta1
          blockDevices:
            - ebs:
                iops: 0
                volumeSize: 120
                volumeType: gp2
          credentialsSecret:
            name: aws-cloud-credentials
          deviceIndex: 0
          iamInstanceProfile:
            id: <infrastructure_id>-worker-profile 12
          instanceType: m4.large
          kind: AWSMachineProviderConfig
          placement:
            availabilityZone: us-east-1a
            region: us-east-1
          securityGroups:
            - filters:
                - name: tag:Name
                  values:
                    - <infrastructure_id>-worker-sg 13
          subnet:
            filters:
              - name: tag:Name
                values:
                  - <infrastructure_id>-private-us-east-1a 14
          tags:
            - name: kubernetes.io/cluster/<infrastructure_id> 15
              value: owned
          userDataSecret:
            name: worker-user-data
1 3 5 12 13 14 15
Specify the infrastructure ID that is based on the cluster ID that you set when you provisioned the cluster. If you have the OpenShift CLI installed, you can obtain the infrastructure ID by running the following command:
$ oc -n openshift-machine-api \
    -o jsonpath='{.spec.template.spec.providerSpec.value.ami.id}{"\n"}' \
    get machineset/<infrastructure_id>-worker-us-east-1a
2 4 8
Specify the infrastructure ID, <infra> node label, and zone.
6 7 9
Specify the <infra> node label.
10
Specify a taint to prevent user workloads from being scheduled on infra nodes.
11
Specify a valid Red Hat Enterprise Linux CoreOS (RHCOS) AMI for your AWS zone for your OpenShift Container Platform nodes.

Machine sets running on AWS support non-guaranteed Spot Instances. You can save on costs by using Spot Instances at a lower price compared to On-Demand Instances on AWS. Configure Spot Instances by adding spotMarketOptions to the MachineSet YAML file.

6.2.1.2. Sample YAML for a machine set custom resource on Azure

This sample YAML defines a machine set that runs in the 1 Microsoft Azure zone in the centralus region and creates nodes that are labeled with node-role.kubernetes.io/infra: "".

In this sample, <infrastructure_id> is the infrastructure ID label that is based on the cluster ID that you set when you provisioned the cluster, and <infra> is the node label to add.

apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id> 1
    machine.openshift.io/cluster-api-machine-role: <infra> 2
    machine.openshift.io/cluster-api-machine-type: <infra> 3
  name: <infrastructure_id>-infra-<region> 4
  namespace: openshift-machine-api
spec:
  replicas: 1
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id> 5
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-infra-<region> 6
  template:
    metadata:
      creationTimestamp: null
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id> 7
        machine.openshift.io/cluster-api-machine-role: <infra> 8
        machine.openshift.io/cluster-api-machine-type: <infra> 9
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-infra-<region> 10
    spec:
      metadata:
        creationTimestamp: null
        labels:
          node-role.kubernetes.io/infra: "" 11
      taints: 12
      - key: node-role.kubernetes.io/infra
        effect: NoSchedule
      providerSpec:
        value:
          apiVersion: azureproviderconfig.openshift.io/v1beta1
          credentialsSecret:
            name: azure-cloud-credentials
            namespace: openshift-machine-api
          image:
            offer: ""
            publisher: ""
            resourceID: /resourceGroups/<infrastructure_id>-rg/providers/Microsoft.Compute/images/<infrastructure_id> 13
            sku: ""
            version: ""
          internalLoadBalancer: ""
          kind: AzureMachineProviderSpec
          location: centralus
          managedIdentity: <infrastructure_id>-identity 14
          metadata:
            creationTimestamp: null
          natRule: null
          networkResourceGroup: ""
          osDisk:
            diskSizeGB: 128
            managedDisk:
              storageAccountType: Premium_LRS
            osType: Linux
          publicIP: false
          publicLoadBalancer: ""
          resourceGroup: <infrastructure_id>-rg 15
          sshPrivateKey: ""
          sshPublicKey: ""
          subnet: <infrastructure_id>-<role>-subnet 16 17
          userDataSecret:
            name: worker-user-data 18
          vmSize: qeci-22538-vnet
          vnet: <infrastructure_id>-vnet 19
          zone: "1" 20
1 5 7 13 14 15 16 19
Specify the infrastructure ID that is based on the cluster ID that you set when you provisioned the cluster. If you have the OpenShift CLI installed, you can obtain the infrastructure ID by running the following command:
$ oc get -o jsonpath='{.status.infrastructureName}{"\n"}' infrastructure cluster

You can obtain the subnet by running the following command:

$  oc -n openshift-machine-api \
    -o jsonpath='{.spec.template.spec.providerSpec.value.subnet}{"\n"}' \
    get machineset/<infrastructure_id>-worker-centralus1

You can obtain the vnet by running the following command:

$  oc -n openshift-machine-api \
    -o jsonpath='{.spec.template.spec.providerSpec.value.vnet}{"\n"}' \
    get machineset/<infrastructure_id>-worker-centralus1
2 3 8 9 11 17 18
Specify the <infra> node label.
4 6 10
Specify the infrastructure ID, <infra> node label, and region.
12
Specify a taint to prevent user workloads from being scheduled on infra nodes.
20
Specify the zone within your region to place machines on. Be sure that your region supports the zone that you specify.

Machine sets running on Azure support non-guaranteed Spot VMs. You can save on costs by using Spot VMs at a lower price compared to standard VMs on Azure. You can configure Spot VMs by adding spotVMOptions to the MachineSet YAML file.

6.2.1.3. Sample YAML for a machine set custom resource on GCP

This sample YAML defines a machine set that runs in Google Cloud Platform (GCP) and creates nodes that are labeled with node-role.kubernetes.io/infra: "".

In this sample, <infrastructure_id> is the infrastructure ID label that is based on the cluster ID that you set when you provisioned the cluster, and <infra> is the node label to add.

apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id> 1
  name: <infrastructure_id>-w-a 2
  namespace: openshift-machine-api
spec:
  replicas: 1
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id> 3
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-w-a 4
  template:
    metadata:
      creationTimestamp: null
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id> 5
        machine.openshift.io/cluster-api-machine-role: <infra> 6
        machine.openshift.io/cluster-api-machine-type: <infra> 7
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-w-a 8
    spec:
      metadata:
        labels:
          node-role.kubernetes.io/infra: "" 9
      taints: 10
      - key: node-role.kubernetes.io/infra
        effect: NoSchedule
      providerSpec:
        value:
          apiVersion: gcpprovider.openshift.io/v1beta1
          canIPForward: false
          credentialsSecret:
            name: gcp-cloud-credentials
          deletionProtection: false
          disks:
          - autoDelete: true
            boot: true
            image: <path_to_image> 11
            labels: null
            sizeGb: 128
            type: pd-ssd
          kind: GCPMachineProviderSpec
          machineType: n1-standard-4
          metadata:
            creationTimestamp: null
          networkInterfaces:
          - network: <infrastructure_id>-network 12
            subnetwork: <infrastructure_id>-worker-subnet 13
          projectID: <project_name> 14
          region: us-central1
          serviceAccounts:
          - email: <infrastructure_id>-w@<project_name>.iam.gserviceaccount.com 15 16
            scopes:
            - https://www.googleapis.com/auth/cloud-platform
          tags:
          - <infrastructure_id>-worker 17
          userDataSecret:
            name: worker-user-data
          zone: us-central1-a
1 2 3 4 5 8 12 13 15 17
Specify the infrastructure ID that is based on the cluster ID that you set when you provisioned the cluster. If you have the OpenShift CLI installed, you can obtain the infrastructure ID by running the following command:
$ oc get -o jsonpath='{.status.infrastructureName}{"\n"}' infrastructure cluster
6 7 9
Specify the <infra> node label.
10
Specify a taint to prevent user workloads from being scheduled on infra nodes.
11
Specify the path to the image that is used in current machine sets. If you have the OpenShift CLI installed, you can obtain the path to the image by running the following command:
$ oc -n openshift-machine-api \
    -o jsonpath='{.spec.template.spec.providerSpec.value.disks[0].image}{"\n"}' \
    get machineset/<infrastructure_id>-worker-a
14 16
Specify the name of the GCP project that you use for your cluster.

Machine sets running on GCP support non-guaranteed preemptible VM instances. You can save on costs by using preemptible VM instances at a lower price compared to normal instances on GCP. You can configure preemptible VM instances by adding preemptible to the MachineSet YAML file.

6.2.1.4. Sample YAML for a machine set custom resource on RHOSP

This sample YAML defines a machine set that runs on Red Hat OpenStack Platform (RHOSP) and creates nodes that are labeled with node-role.kubernetes.io/infra: "".

In this sample, <infrastructure_id> is the infrastructure ID label that is based on the cluster ID that you set when you provisioned the cluster, and <infra> is the node label to add.

apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id> 1
    machine.openshift.io/cluster-api-machine-role: <infra> 2
    machine.openshift.io/cluster-api-machine-type: <infra> 3
  name: <infrastructure_id>-infra 4
  namespace: openshift-machine-api
spec:
  replicas: <number_of_replicas>
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id> 5
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-infra 6
  template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id> 7
        machine.openshift.io/cluster-api-machine-role: <infra> 8
        machine.openshift.io/cluster-api-machine-type: <infra> 9
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-infra 10
    spec:
    metadata:
      creationTimestamp: null
      labels:
        node-role.kubernetes.io/infra: ""
      taints: 11
      - key: node-role.kubernetes.io/infra
        effect: NoSchedule
      providerSpec:
        value:
          apiVersion: openstackproviderconfig.openshift.io/v1alpha1
          cloudName: openstack
          cloudsSecret:
            name: openstack-cloud-credentials
            namespace: openshift-machine-api
          flavor: <nova_flavor>
          image: <glance_image_name_or_location>
          serverGroupID: <optional_UUID_of_server_group> 12
          kind: OpenstackProviderSpec
          networks: 13
          - filter: {}
            subnets:
            - filter:
                name: <subnet_name>
                tags: openshiftClusterID=<infrastructure_id> 14
          primarySubnet: <rhosp_subnet_UUID> 15
          securityGroups:
          - filter: {}
            name: <infrastructure_id>-worker 16
          serverMetadata:
            Name: <infrastructure_id>-worker 17
            openshiftClusterID: <infrastructure_id> 18
          tags:
          - openshiftClusterID=<infrastructure_id> 19
          trunk: true
          userDataSecret:
            name: worker-user-data 20
          availabilityZone: <optional_openstack_availability_zone>
1 5 7 14 16 17 18 19
Specify the infrastructure ID that is based on the cluster ID that you set when you provisioned the cluster. If you have the OpenShift CLI installed, you can obtain the infrastructure ID by running the following command:
$ oc get -o jsonpath='{.status.infrastructureName}{"\n"}' infrastructure cluster
2 3 8 9 20
Specify the <infra> node label.
4 6 10
Specify the infrastructure ID and <infra> node label.
11
Specify a taint to prevent user workloads from being scheduled on infra nodes.
12
To set a server group policy for the MachineSet, enter the value that is returned from creating a server group. For most deployments, anti-affinity or soft-anti-affinity policies are recommended.
13
Required for deployments to multiple networks. If deploying to multiple networks, this list must include the network that is used as the primarySubnet value.
15
Specify the RHOSP subnet that you want the endpoints of nodes to be published on. Usually, this is the same subnet that is used as the value of machinesSubnet in the install-config.yaml file.

6.2.1.5. Sample YAML for a machine set custom resource on vSphere

This sample YAML defines a machine set that runs on VMware vSphere and creates nodes that are labeled with node-role.kubernetes.io/infra: "".

In this sample, <infrastructure_id> is the infrastructure ID label that is based on the cluster ID that you set when you provisioned the cluster, and <infra> is the node label to add.

apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  creationTimestamp: null
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id> 1
  name: <infrastructure_id>-infra 2
  namespace: openshift-machine-api
spec:
  replicas: 1
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id> 3
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-infra 4
  template:
    metadata:
      creationTimestamp: null
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id> 5
        machine.openshift.io/cluster-api-machine-role: <infra> 6
        machine.openshift.io/cluster-api-machine-type: <infra> 7
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-infra 8
    spec:
      metadata:
        creationTimestamp: null
        labels:
          node-role.kubernetes.io/infra: "" 9
      taints: 10
      - key: node-role.kubernetes.io/infra
        effect: NoSchedule
      providerSpec:
        value:
          apiVersion: vsphereprovider.openshift.io/v1beta1
          credentialsSecret:
            name: vsphere-cloud-credentials
          diskGiB: 120
          kind: VSphereMachineProviderSpec
          memoryMiB: 8192
          metadata:
            creationTimestamp: null
          network:
            devices:
            - networkName: "<vm_network_name>" 11
          numCPUs: 4
          numCoresPerSocket: 1
          snapshot: ""
          template: <vm_template_name> 12
          userDataSecret:
            name: worker-user-data
          workspace:
            datacenter: <vcenter_datacenter_name> 13
            datastore: <vcenter_datastore_name> 14
            folder: <vcenter_vm_folder_path> 15
            resourcepool: <vsphere_resource_pool> 16
            server: <vcenter_server_ip> 17
1 3 5
Specify the infrastructure ID that is based on the cluster ID that you set when you provisioned the cluster. If you have the OpenShift CLI (oc) installed, you can obtain the infrastructure ID by running the following command:
$ oc get -o jsonpath='{.status.infrastructureName}{"\n"}' infrastructure cluster
2 4 8
Specify the infrastructure ID and <infra> node label.
6 7 9
Specify the <infra> node label.
10
Specify a taint to prevent user workloads from being scheduled on infra nodes.
11
Specify the vSphere VM network to deploy the machine set to.
12
Specify the vSphere VM template to use, such as user-5ddjd-rhcos.
13
Specify the vCenter Datacenter to deploy the machine set on.
14
Specify the vCenter Datastore to deploy the machine set on.
15
Specify the path to the vSphere VM folder in vCenter, such as /dc1/vm/user-inst-5ddjd.
16
Specify the vSphere resource pool for your VMs.
17
Specify the vCenter server IP or fully qualified domain name.

6.2.2. Creating a machine set

In addition to the ones created by the installation program, you can create your own machine sets to dynamically manage the machine compute resources for specific workloads of your choice.

Prerequisites

  • Deploy an OpenShift Container Platform cluster.
  • Install the OpenShift CLI (oc).
  • Log in to oc as a user with cluster-admin permission.

Procedure

  1. Create a new YAML file that contains the machine set custom resource (CR) sample and is named <file_name>.yaml.

    Ensure that you set the <clusterID> and <role> parameter values.

    1. If you are not sure which value to set for a specific field, you can check an existing machine set from your cluster:

      $ oc get machinesets -n openshift-machine-api

      Example output

      NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
      agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1d   0         0                             55m
      agl030519-vplxk-worker-us-east-1e   0         0                             55m
      agl030519-vplxk-worker-us-east-1f   0         0                             55m

    2. Check values of a specific machine set:

      $ oc get machineset <machineset_name> -n \
           openshift-machine-api -o yaml

      Example output

      ...
      template:
          metadata:
            labels:
              machine.openshift.io/cluster-api-cluster: agl030519-vplxk 1
              machine.openshift.io/cluster-api-machine-role: worker 2
              machine.openshift.io/cluster-api-machine-type: worker
              machine.openshift.io/cluster-api-machineset: agl030519-vplxk-worker-us-east-1a

      1
      The cluster ID.
      2
      A default node label.
  2. Create the new MachineSet CR:

    $ oc create -f <file_name>.yaml
  3. View the list of machine sets:

    $ oc get machineset -n openshift-machine-api

    Example output

    NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
    agl030519-vplxk-infra-us-east-1a    1         1         1       1           11m
    agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
    agl030519-vplxk-worker-us-east-1d   0         0                             55m
    agl030519-vplxk-worker-us-east-1e   0         0                             55m
    agl030519-vplxk-worker-us-east-1f   0         0                             55m

    When the new machine set is available, the DESIRED and CURRENT values match. If the machine set is not available, wait a few minutes and run the command again.

6.2.3. Creating an infrastructure node

Important

See Creating infrastructure machine sets for installer-provisioned infrastructure environments or for any cluster where the control plane nodes (also known as the master nodes) are managed by the machine API.

Requirements of the cluster dictate that infrastructure, also called infra nodes, be provisioned. The installer only provides provisions for control plane and worker nodes. Worker nodes can be designated as infrastructure nodes or application, also called app, nodes through labeling.

Procedure

  1. Add a label to the worker node that you want to act as application node:

    $ oc label node <node-name> node-role.kubernetes.io/app=""
  2. Add a label to the worker nodes that you want to act as infrastructure nodes:

    $ oc label node <node-name> node-role.kubernetes.io/infra=""
  3. Check to see if applicable nodes now have the infra role and app roles:

    $ oc get nodes
  4. Create a default cluster-wide node selector. The default node selector is applied to pods created in all namespaces. This creates an intersection with any existing node selectors on a pod, which additionally constrains the pod’s selector.

    Important

    If the default node selector key conflicts with the key of a pod’s label, then the default node selector is not applied.

    However, do not set a default node selector that might cause a pod to become unschedulable. For example, setting the default node selector to a specific node role, such as node-role.kubernetes.io/infra="", when a pod’s label is set to a different node role, such as node-role.kubernetes.io/master="", can cause the pod to become unschedulable. For this reason, it is not recommended to set the default node selector to specific node roles.

    You can alternatively use a project node selector to avoid cluster-wide node selector key conflicts.

    1. Edit the Scheduler object:

      $ oc edit scheduler cluster
    2. Add the defaultNodeSelector field with the appropriate node selector:

      apiVersion: config.openshift.io/v1
      kind: Scheduler
      metadata:
        name: cluster
      ...
      spec:
        defaultNodeSelector: node-role.kubernetes.io/app= 1
      ...
      1
      This example node selector deploys pods on app nodes by default.
    3. Save the file to apply the changes.
  5. Move infrastructure resources to the newly labeled infra nodes.

6.2.4. Creating a machine config pool for infrastructure machines

If you need infrastructure machines to have dedicated configurations, you must create an infra pool.

Procedure

  1. Add a label to the node you want to assign as the infra node with a specific label:

    $ oc label node <node_name> <label>
    $ oc label node ci-ln-n8mqwr2-f76d1-xscn2-worker-c-6fmtx node-role.kubernetes.io/infra=
  2. Create a machine config pool that contains both the worker role and your custom role as machine config selector:

    $ cat infra.mcp.yaml

    Example output

    apiVersion: machineconfiguration.openshift.io/v1
    kind: MachineConfigPool
    metadata:
      name: infra
    spec:
      machineConfigSelector:
        matchExpressions:
          - {key: machineconfiguration.openshift.io/role, operator: In, values: [worker,infra]} 1
      nodeSelector:
        matchLabels:
          node-role.kubernetes.io/infra: "" 2

    1
    Add the worker role and your custom role.
    2
    Add the label you added to the node as a nodeSelector.
    Note

    Custom machine config pools inherit machine configs from the worker pool. Custom pools use any machine config targeted for the worker pool, but add the ability to also deploy changes that are targeted at only the custom pool. Because a custom pool inherits resources from the worker pool, any change to the worker pool also affects the custom pool.

  3. After you have the YAML file, you can create the machine config pool:

    $ oc create -f infra.mcp.yaml
  4. Check the machine configs to ensure that the infrastructure configuration rendered successfully:

    $ oc get machineconfig

    Example output

    NAME                                                        GENERATEDBYCONTROLLER                      IGNITIONVERSION   CREATED
    00-master                                                   365c1cfd14de5b0e3b85e0fc815b0060f36ab955   2.2.0             31d
    00-worker                                                   365c1cfd14de5b0e3b85e0fc815b0060f36ab955   2.2.0             31d
    01-master-container-runtime                                 365c1cfd14de5b0e3b85e0fc815b0060f36ab955   2.2.0             31d
    01-master-kubelet                                           365c1cfd14de5b0e3b85e0fc815b0060f36ab955   2.2.0             31d
    01-worker-container-runtime                                 365c1cfd14de5b0e3b85e0fc815b0060f36ab955   2.2.0             31d
    01-worker-kubelet                                           365c1cfd14de5b0e3b85e0fc815b0060f36ab955   2.2.0             31d
    99-master-1ae2a1e0-a115-11e9-8f14-005056899d54-registries   365c1cfd14de5b0e3b85e0fc815b0060f36ab955   2.2.0             31d
    99-master-ssh                                                                                          2.2.0             31d
    99-worker-1ae64748-a115-11e9-8f14-005056899d54-registries   365c1cfd14de5b0e3b85e0fc815b0060f36ab955   2.2.0             31d
    99-worker-ssh                                                                                          2.2.0             31d
    rendered-infra-4e48906dca84ee702959c71a53ee80e7             365c1cfd14de5b0e3b85e0fc815b0060f36ab955   2.2.0             19s
    rendered-master-072d4b2da7f88162636902b074e9e28e            5b6fb8349a29735e48446d435962dec4547d3090   2.2.0             31d
    rendered-master-3e88ec72aed3886dec061df60d16d1af            02c07496ba0417b3e12b78fb32baf6293d314f79   2.2.0             31d
    rendered-master-419bee7de96134963a15fdf9dd473b25            365c1cfd14de5b0e3b85e0fc815b0060f36ab955   2.2.0             17d
    rendered-master-53f5c91c7661708adce18739cc0f40fb            365c1cfd14de5b0e3b85e0fc815b0060f36ab955   2.2.0             13d
    rendered-master-a6a357ec18e5bce7f5ac426fc7c5ffcd            365c1cfd14de5b0e3b85e0fc815b0060f36ab955   2.2.0             7d3h
    rendered-master-dc7f874ec77fc4b969674204332da037            5b6fb8349a29735e48446d435962dec4547d3090   2.2.0             31d
    rendered-worker-1a75960c52ad18ff5dfa6674eb7e533d            5b6fb8349a29735e48446d435962dec4547d3090   2.2.0             31d
    rendered-worker-2640531be11ba43c61d72e82dc634ce6            5b6fb8349a29735e48446d435962dec4547d3090   2.2.0             31d
    rendered-worker-4e48906dca84ee702959c71a53ee80e7            365c1cfd14de5b0e3b85e0fc815b0060f36ab955   2.2.0             7d3h
    rendered-worker-4f110718fe88e5f349987854a1147755            365c1cfd14de5b0e3b85e0fc815b0060f36ab955   2.2.0             17d
    rendered-worker-afc758e194d6188677eb837842d3b379            02c07496ba0417b3e12b78fb32baf6293d314f79   2.2.0             31d
    rendered-worker-daa08cc1e8f5fcdeba24de60cd955cc3            365c1cfd14de5b0e3b85e0fc815b0060f36ab955   2.2.0             13d

    You should see a new machine config, with the rendered-infra-* prefix.

  5. Optional: To deploy changes to a custom pool, create a machine config that uses the custom pool name as the label, such as infra. Note that this is not required and only shown for instructional purposes. In this manner, you can apply any custom configurations specific to only your infra nodes.

    Note

    After you create the new machine config pool, the MCO generates a new rendered config for that pool, and associated nodes of that pool reboot to apply the new configuration.

    1. Create a machine config:

      $ cat infra.mc.yaml

      Example output

      apiVersion: machineconfiguration.openshift.io/v1
      kind: MachineConfig
      metadata:
        name: 51-infra
        labels:
          machineconfiguration.openshift.io/role: infra 1
      spec:
        config:
          ignition:
            version: 3.1.0
          storage:
            files:
            - path: /etc/infratest
              mode: 0644
              contents:
                source: data:,infra

      1
      Add the label you added to the node as a nodeSelector.
    2. Apply the machine config to the infra-labeled nodes:

      $ oc create -f infra.mc.yaml
  6. Confirm that your new machine config pool is available:

    $ oc get mcp

    Example output

    NAME     CONFIG                                             UPDATED   UPDATING   DEGRADED   MACHINECOUNT   READYMACHINECOUNT   UPDATEDMACHINECOUNT   DEGRADEDMACHINECOUNT   AGE
    infra    rendered-infra-60e35c2e99f42d976e084fa94da4d0fc    True      False      False      1              1                   1                     0                      4m20s
    master   rendered-master-9360fdb895d4c131c7c4bebbae099c90   True      False      False      3              3                   3                     0                      91m
    worker   rendered-worker-60e35c2e99f42d976e084fa94da4d0fc   True      False      False      2              2                   2                     0                      91m

    In this example, a worker node was changed to an infra node.

Additional resources

6.3. Assigning machine set resources to infrastructure nodes

After creating an infrastructure machine set, the worker and infra roles are applied to new infra nodes. Nodes with the infra role applied are not counted toward the total number of subscriptions that are required to run the environment, even when the worker role is also applied.

However, with an infra node being assigned as a worker, there is a chance user workloads could get inadvertently assigned to an infra node. To avoid this, you can apply a taint to the infra node and tolerations for the pods you want to control.

6.3.1. Binding infrastructure node workloads using taints and tolerations

If you have an infra node that has the infra and worker roles assigned, you must configure the node so that user workloads are not assigned to it.

Important

It is recommended that you preserve the dual infra,worker label that is created for infra nodes and use taints and tolerations to manage nodes that user workloads are scheduled on. If you remove the worker label from the node, you must create a custom pool to manage it. A node with a label other than master or worker is not recognized by the MCO without a custom pool. Maintaining the worker label allows the node to be managed by the default worker machine config pool, if no custom pools that select the custom label exists. The infra label communicates to the cluster that it does not count toward the total number of subscriptions.

Prerequisites

  • Configure additional MachineSet objects in your OpenShift Container Platform cluster.

Procedure

  1. Add a taint to the infra node to prevent scheduling user workloads on it:

    1. Determine if the node has the taint:

      $ oc describe nodes <node_name>

      Sample output

      oc describe node ci-ln-iyhx092-f76d1-nvdfm-worker-b-wln2l
      Name:               ci-ln-iyhx092-f76d1-nvdfm-worker-b-wln2l
      Roles:              worker
       ...
      Taints:             node-role.kubernetes.io/infra:NoSchedule
       ...

      This example shows that the node has a taint. You can proceed with adding a toleration to your pod in the next step.

    2. If you have not configured a taint to prevent scheduling user workloads on it:

      $ oc adm taint nodes <node_name> <key>:<effect>

      For example:

      $ oc adm taint nodes node1 node-role.kubernetes.io/infra:NoSchedule

      This example places a taint on node1 that has key node-role.kubernetes.io/infra and taint effect NoSchedule. Nodes with the NoSchedule effect schedule only pods that tolerate the taint, but allow existing pods to remain scheduled on the node.

      Note

      If a descheduler is used, pods violating node taints could be evicted from the cluster.

  2. Add tolerations for the pod configurations you want to schedule on the infra node, like router, registry, and monitoring workloads. Add the following code to the Pod object specification:

    tolerations:
      - effect: NoSchedule 1
        key: node-role.kubernetes.io/infra 2
        operator: Exists 3
    1
    Specify the effect that you added to the node.
    2
    Specify the key that you added to the node.
    3
    Specify the Exists Operator to require a taint with the key node-role.kubernetes.io/infra to be present on the node.

    This toleration matches the taint created by the oc adm taint command. A pod with this toleration can be scheduled onto the infra node.

    Note

    Moving pods for an Operator installed via OLM to an infra node is not always possible. The capability to move Operator pods depends on the configuration of each Operator.

  3. Schedule the pod to the infra node using a scheduler. See the documentation for Controlling pod placement onto nodes for details.

Additional resources

6.4. Moving resources to infrastructure machine sets

Some of the infrastructure resources are deployed in your cluster by default. You can move them to the infrastructure machine sets that you created.

6.4.1. Moving the router

You can deploy the router pod to a different machine set. By default, the pod is deployed to a worker node.

Prerequisites

  • Configure additional machine sets in your OpenShift Container Platform cluster.

Procedure

  1. View the IngressController custom resource for the router Operator:

    $ oc get ingresscontroller default -n openshift-ingress-operator -o yaml

    The command output resembles the following text:

    apiVersion: operator.openshift.io/v1
    kind: IngressController
    metadata:
      creationTimestamp: 2019-04-18T12:35:39Z
      finalizers:
      - ingresscontroller.operator.openshift.io/finalizer-ingresscontroller
      generation: 1
      name: default
      namespace: openshift-ingress-operator
      resourceVersion: "11341"
      selfLink: /apis/operator.openshift.io/v1/namespaces/openshift-ingress-operator/ingresscontrollers/default
      uid: 79509e05-61d6-11e9-bc55-02ce4781844a
    spec: {}
    status:
      availableReplicas: 2
      conditions:
      - lastTransitionTime: 2019-04-18T12:36:15Z
        status: "True"
        type: Available
      domain: apps.<cluster>.example.com
      endpointPublishingStrategy:
        type: LoadBalancerService
      selector: ingresscontroller.operator.openshift.io/deployment-ingresscontroller=default
  2. Edit the ingresscontroller resource and change the nodeSelector to use the infra label:

    $ oc edit ingresscontroller default -n openshift-ingress-operator

    Add the nodeSelector stanza that references the infra label to the spec section, as shown:

      spec:
        nodePlacement:
          nodeSelector:
            matchLabels:
              node-role.kubernetes.io/infra: ""
  3. Confirm that the router pod is running on the infra node.

    1. View the list of router pods and note the node name of the running pod:

      $ oc get pod -n openshift-ingress -o wide

      Example output

      NAME                              READY     STATUS        RESTARTS   AGE       IP           NODE                           NOMINATED NODE   READINESS GATES
      router-default-86798b4b5d-bdlvd   1/1      Running       0          28s       10.130.2.4   ip-10-0-217-226.ec2.internal   <none>           <none>
      router-default-955d875f4-255g8    0/1      Terminating   0          19h       10.129.2.4   ip-10-0-148-172.ec2.internal   <none>           <none>

      In this example, the running pod is on the ip-10-0-217-226.ec2.internal node.

    2. View the node status of the running pod:

      $ oc get node <node_name> 1
      1
      Specify the <node_name> that you obtained from the pod list.

      Example output

      NAME                          STATUS  ROLES         AGE   VERSION
      ip-10-0-217-226.ec2.internal  Ready   infra,worker  17h   v1.19.0

      Because the role list includes infra, the pod is running on the correct node.

6.4.2. Moving the default registry

You configure the registry Operator to deploy its pods to different nodes.

Prerequisites

  • Configure additional machine sets in your OpenShift Container Platform cluster.

Procedure

  1. View the config/instance object:

    $ oc get configs.imageregistry.operator.openshift.io/cluster -o yaml

    Example output

    apiVersion: imageregistry.operator.openshift.io/v1
    kind: Config
    metadata:
      creationTimestamp: 2019-02-05T13:52:05Z
      finalizers:
      - imageregistry.operator.openshift.io/finalizer
      generation: 1
      name: cluster
      resourceVersion: "56174"
      selfLink: /apis/imageregistry.operator.openshift.io/v1/configs/cluster
      uid: 36fd3724-294d-11e9-a524-12ffeee2931b
    spec:
      httpSecret: d9a012ccd117b1e6616ceccb2c3bb66a5fed1b5e481623
      logging: 2
      managementState: Managed
      proxy: {}
      replicas: 1
      requests:
        read: {}
        write: {}
      storage:
        s3:
          bucket: image-registry-us-east-1-c92e88cad85b48ec8b312344dff03c82-392c
          region: us-east-1
    status:
    ...

  2. Edit the config/instance object:

    $ oc edit configs.imageregistry.operator.openshift.io/cluster
  3. Modify the spec section of the object to resemble the following YAML:

    spec:
      affinity:
        podAntiAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
          - podAffinityTerm:
              namespaces:
              - openshift-image-registry
              topologyKey: kubernetes.io/hostname
            weight: 100
      logLevel: Normal
      managementState: Managed
      nodeSelector:
        node-role.kubernetes.io/infra: ""
  4. Verify the registry pod has been moved to the infrastructure node.

    1. Run the following command to identify the node where the registry pod is located:

      $ oc get pods -o wide -n openshift-image-registry
    2. Confirm the node has the label you specified:

      $ oc describe node <node_name>

      Review the command output and confirm that node-role.kubernetes.io/infra is in the LABELS list.

6.4.3. Moving the monitoring solution

By default, the Prometheus Cluster Monitoring stack, which contains Prometheus, Grafana, and AlertManager, is deployed to provide cluster monitoring. It is managed by the Cluster Monitoring Operator. To move its components to different machines, you create and apply a custom config map.

Procedure

  1. Save the following ConfigMap definition as the cluster-monitoring-configmap.yaml file:

    apiVersion: v1
    kind: ConfigMap
    metadata:
      name: cluster-monitoring-config
      namespace: openshift-monitoring
    data:
      config.yaml: |+
        alertmanagerMain:
          nodeSelector:
            node-role.kubernetes.io/infra: ""
        prometheusK8s:
          nodeSelector:
            node-role.kubernetes.io/infra: ""
        prometheusOperator:
          nodeSelector:
            node-role.kubernetes.io/infra: ""
        grafana:
          nodeSelector:
            node-role.kubernetes.io/infra: ""
        k8sPrometheusAdapter:
          nodeSelector:
            node-role.kubernetes.io/infra: ""
        kubeStateMetrics:
          nodeSelector:
            node-role.kubernetes.io/infra: ""
        telemeterClient:
          nodeSelector:
            node-role.kubernetes.io/infra: ""
        openshiftStateMetrics:
          nodeSelector:
            node-role.kubernetes.io/infra: ""
        thanosQuerier:
          nodeSelector:
            node-role.kubernetes.io/infra: ""

    Running this config map forces the components of the monitoring stack to redeploy to infrastructure nodes.

  2. Apply the new config map:

    $ oc create -f cluster-monitoring-configmap.yaml
  3. Watch the monitoring pods move to the new machines:

    $ watch 'oc get pod -n openshift-monitoring -o wide'
  4. If a component has not moved to the infra node, delete the pod with this component:

    $ oc delete pod -n openshift-monitoring <pod>

    The component from the deleted pod is re-created on the infra node.

6.4.4. Moving the cluster logging resources

You can configure the Cluster Logging Operator to deploy the pods for any or all of the Cluster Logging components, Elasticsearch, Kibana, and Curator to different nodes. You cannot move the Cluster Logging Operator pod from its installed location.

For example, you can move the Elasticsearch pods to a separate node because of high CPU, memory, and disk requirements.

Prerequisites

  • Cluster logging and Elasticsearch must be installed. These features are not installed by default.

Procedure

  1. Edit the ClusterLogging custom resource (CR) in the openshift-logging project:

    $ oc edit ClusterLogging instance
    apiVersion: logging.openshift.io/v1
    kind: ClusterLogging
    
    ...
    
    spec:
      collection:
        logs:
          fluentd:
            resources: null
          type: fluentd
      curation:
        curator:
          nodeSelector: 1
            node-role.kubernetes.io/infra: ''
          resources: null
          schedule: 30 3 * * *
        type: curator
      logStore:
        elasticsearch:
          nodeCount: 3
          nodeSelector: 2
            node-role.kubernetes.io/infra: ''
          redundancyPolicy: SingleRedundancy
          resources:
            limits:
              cpu: 500m
              memory: 16Gi
            requests:
              cpu: 500m
              memory: 16Gi
          storage: {}
        type: elasticsearch
      managementState: Managed
      visualization:
        kibana:
          nodeSelector: 3
            node-role.kubernetes.io/infra: ''
          proxy:
            resources: null
          replicas: 1
          resources: null
        type: kibana
    
    ...
1 2 3
Add a nodeSelector parameter with the appropriate value to the component you want to move. You can use a nodeSelector in the format shown or use <key>: <value> pairs, based on the value specified for the node.

Verification

To verify that a component has moved, you can use the oc get pod -o wide command.

For example:

  • You want to move the Kibana pod from the ip-10-0-147-79.us-east-2.compute.internal node:

    $ oc get pod kibana-5b8bdf44f9-ccpq9 -o wide

    Example output

    NAME                      READY   STATUS    RESTARTS   AGE   IP            NODE                                        NOMINATED NODE   READINESS GATES
    kibana-5b8bdf44f9-ccpq9   2/2     Running   0          27s   10.129.2.18   ip-10-0-147-79.us-east-2.compute.internal   <none>           <none>

  • You want to move the Kibana Pod to the ip-10-0-139-48.us-east-2.compute.internal node, a dedicated infrastructure node:

    $ oc get nodes

    Example output

    NAME                                         STATUS   ROLES          AGE   VERSION
    ip-10-0-133-216.us-east-2.compute.internal   Ready    master         60m   v1.19.0
    ip-10-0-139-146.us-east-2.compute.internal   Ready    master         60m   v1.19.0
    ip-10-0-139-192.us-east-2.compute.internal   Ready    worker         51m   v1.19.0
    ip-10-0-139-241.us-east-2.compute.internal   Ready    worker         51m   v1.19.0
    ip-10-0-147-79.us-east-2.compute.internal    Ready    worker         51m   v1.19.0
    ip-10-0-152-241.us-east-2.compute.internal   Ready    master         60m   v1.19.0
    ip-10-0-139-48.us-east-2.compute.internal    Ready    infra          51m   v1.19.0

    Note that the node has a node-role.kubernetes.io/infra: '' label:

    $ oc get node ip-10-0-139-48.us-east-2.compute.internal -o yaml

    Example output

    kind: Node
    apiVersion: v1
    metadata:
      name: ip-10-0-139-48.us-east-2.compute.internal
      selfLink: /api/v1/nodes/ip-10-0-139-48.us-east-2.compute.internal
      uid: 62038aa9-661f-41d7-ba93-b5f1b6ef8751
      resourceVersion: '39083'
      creationTimestamp: '2020-04-13T19:07:55Z'
      labels:
        node-role.kubernetes.io/infra: ''
    ...

  • To move the Kibana pod, edit the ClusterLogging CR to add a node selector:

    apiVersion: logging.openshift.io/v1
    kind: ClusterLogging
    
    ...
    
    spec:
    
    ...
    
      visualization:
        kibana:
          nodeSelector: 1
            node-role.kubernetes.io/infra: ''
          proxy:
            resources: null
          replicas: 1
          resources: null
        type: kibana
    1
    Add a node selector to match the label in the node specification.
  • After you save the CR, the current Kibana pod is terminated and new pod is deployed:

    $ oc get pods

    Example output

    NAME                                            READY   STATUS        RESTARTS   AGE
    cluster-logging-operator-84d98649c4-zb9g7       1/1     Running       0          29m
    elasticsearch-cdm-hwv01pf7-1-56588f554f-kpmlg   2/2     Running       0          28m
    elasticsearch-cdm-hwv01pf7-2-84c877d75d-75wqj   2/2     Running       0          28m
    elasticsearch-cdm-hwv01pf7-3-f5d95b87b-4nx78    2/2     Running       0          28m
    fluentd-42dzz                                   1/1     Running       0          28m
    fluentd-d74rq                                   1/1     Running       0          28m
    fluentd-m5vr9                                   1/1     Running       0          28m
    fluentd-nkxl7                                   1/1     Running       0          28m
    fluentd-pdvqb                                   1/1     Running       0          28m
    fluentd-tflh6                                   1/1     Running       0          28m
    kibana-5b8bdf44f9-ccpq9                         2/2     Terminating   0          4m11s
    kibana-7d85dcffc8-bfpfp                         2/2     Running       0          33s

  • The new pod is on the ip-10-0-139-48.us-east-2.compute.internal node:

    $ oc get pod kibana-7d85dcffc8-bfpfp -o wide

    Example output

    NAME                      READY   STATUS        RESTARTS   AGE   IP            NODE                                        NOMINATED NODE   READINESS GATES
    kibana-7d85dcffc8-bfpfp   2/2     Running       0          43s   10.131.0.22   ip-10-0-139-48.us-east-2.compute.internal   <none>           <none>

  • After a few moments, the original Kibana pod is removed.

    $ oc get pods

    Example output

    NAME                                            READY   STATUS    RESTARTS   AGE
    cluster-logging-operator-84d98649c4-zb9g7       1/1     Running   0          30m
    elasticsearch-cdm-hwv01pf7-1-56588f554f-kpmlg   2/2     Running   0          29m
    elasticsearch-cdm-hwv01pf7-2-84c877d75d-75wqj   2/2     Running   0          29m
    elasticsearch-cdm-hwv01pf7-3-f5d95b87b-4nx78    2/2     Running   0          29m
    fluentd-42dzz                                   1/1     Running   0          29m
    fluentd-d74rq                                   1/1     Running   0          29m
    fluentd-m5vr9                                   1/1     Running   0          29m
    fluentd-nkxl7                                   1/1     Running   0          29m
    fluentd-pdvqb                                   1/1     Running   0          29m
    fluentd-tflh6                                   1/1     Running   0          29m
    kibana-7d85dcffc8-bfpfp                         2/2     Running   0          62s

Additional resources

Chapter 7. Adding RHEL compute machines to an OpenShift Container Platform cluster

In OpenShift Container Platform, you can add Red Hat Enterprise Linux (RHEL) compute, or worker, machines to a user-provisioned infrastructure cluster or a installation-provisioned infrastructure cluster. You can use RHEL as the operating system on only compute machines.

7.1. About adding RHEL compute nodes to a cluster

In OpenShift Container Platform 4.6, you have the option of using Red Hat Enterprise Linux (RHEL) machines as compute machines, which are also known as worker machines, in your cluster if you use a user-provisioned infrastructure installation. You must use Red Hat Enterprise Linux CoreOS (RHCOS) machines for the control plane, or master, machines in your cluster.

As with all installations that use user-provisioned infrastructure, if you choose to use RHEL compute machines in your cluster, you take responsibility for all operating system life cycle management and maintenance, including performing system updates, applying patches, and completing all other required tasks.

Important

Because removing OpenShift Container Platform from a machine in the cluster requires destroying the operating system, you must use dedicated hardware for any RHEL machines that you add to the cluster.

Important

Swap memory is disabled on all RHEL machines that you add to your OpenShift Container Platform cluster. You cannot enable swap memory on these machines.

You must add any RHEL compute machines to the cluster after you initialize the control plane.

7.2. System requirements for RHEL compute nodes

The Red Hat Enterprise Linux (RHEL) compute, or worker, machine hosts in your OpenShift Container Platform environment must meet the following minimum hardware specifications and system-level requirements:

  • You must have an active OpenShift Container Platform subscription on your Red Hat account. If you do not, contact your sales representative for more information.
  • Production environments must provide compute machines to support your expected workloads. As a cluster administrator, you must calculate the expected workload and add about 10 percent for overhead. For production environments, allocate enough resources so that a node host failure does not affect your maximum capacity.
  • Each system must meet the following hardware requirements:

    • Physical or virtual system, or an instance running on a public or private IaaS.
    • Base OS: RHEL 7.9 with "Minimal" installation option.

      Important

      Adding RHEL 7 compute machines to an OpenShift Container Platform cluster is deprecated. Deprecated functionality is still included in OpenShift Container Platform and continues to be supported; however, it will be removed in a future release of this product and is not recommended for new deployments.

      In addition, you must not upgrade your compute machines to RHEL 8 because support is not available in this release.

      For the most recent list of major functionality that has been deprecated or removed within OpenShift Container Platform, refer to the Deprecated and removed features section of the OpenShift Container Platform release notes.

    • If you deployed OpenShift Container Platform in FIPS mode, you must enable FIPS on the RHEL machine before you boot it. See Enabling FIPS Mode in the RHEL 7 documentation.
Important

The use of FIPS Validated / Modules in Process cryptographic libraries is only supported on OpenShift Container Platform deployments on the x86_64 architecture.

  • NetworkManager 1.0 or later.
  • 1 vCPU.
  • Minimum 8 GB RAM.
  • Minimum 15 GB hard disk space for the file system containing /var/.
  • Minimum 1 GB hard disk space for the file system containing /usr/local/bin/.
  • Minimum 1 GB hard disk space for the file system containing the system’s temporary directory. The system’s temporary directory is determined according to the rules defined in the tempfile module in Python’s standard library.

    • Each system must meet any additional requirements for your system provider. For example, if you installed your cluster on VMware vSphere, your disks must be configured according to its storage guidelines and the disk.enableUUID=true attribute must be set.
    • Each system must be able to access the cluster’s API endpoints by using DNS-resolvable hostnames. Any network security access control that is in place must allow the system access to the cluster’s API service endpoints.

7.2.1. Certificate signing requests management

Because your cluster has limited access to automatic machine management when you use infrastructure that you provision, you must provide a mechanism for approving cluster certificate signing requests (CSRs) after installation. The kube-controller-manager only approves the kubelet client CSRs. The machine-approver cannot guarantee the validity of a serving certificate that is requested by using kubelet credentials because it cannot confirm that the correct machine issued the request. You must determine and implement a method of verifying the validity of the kubelet serving certificate requests and approving them.

7.3. Preparing an image for your cloud

Amazon Machine Images (AMI) are required because various image formats cannot be used directly by AWS. You may use the AMIs that Red Hat has provided, or you can manually import your own images. The AMI must exist before the EC2 instance can be provisioned. You will need a valid AMI ID so that the correct RHEL version needed for the compute machines is selected.

7.3.1. Listing latest available RHEL images on AWS

AMI IDs correspond to native boot images for AWS. Because an AMI must exist before the EC2 instance is provisioned, you will need to know the AMI ID before configuration. The AWS Command Line Interface (CLI) is used to list the available Red Hat Enterprise Linux (RHEL) image IDs.

Prerequisites

  • You have installed the AWS CLI.

Procedure

  • Use this command to list RHEL 7.9 Amazon Machine Images (AMI):

    $ aws ec2 describe-images --owners 309956199498 \ 1
    --query 'sort_by(Images, &CreationDate)[*].[CreationDate,Name,ImageId]' \ 2
    --filters "Name=name,Values=RHEL-7.9*" \ 3
    --region us-east-1 \ 4
    --output table 5
    1
    The --owners command option shows Red Hat images based on the account ID 309956199498.
    Important

    This account ID is required to display AMI IDs for images that are provided by Red Hat.

    2
    The --query command option sets how the images are sorted with the parameters 'sort_by(Images, &CreationDate)[*].[CreationDate,Name,ImageId]'. In this case, the images are sorted by the creation date, and the table is structured to show the creation date, the name of the image, and the AMI IDs.
    3
    The --filter command option sets which version of RHEL is shown. In this example, since the filter is set by "Name=name,Values=RHEL-7.9*", then RHEL 7.9 AMIs are shown.
    4
    The --region command option sets where the region where an AMI is stored.
    5
    The --output command option sets how the results are displayed.
Note

When creating a RHEL compute machine for AWS, ensure that the AMI is RHEL 7.9.

Example output

----------------------------------------------------------------------------------------------------------
|                                             DescribeImages                                             |
+---------------------------+----------------------------------------------------+-----------------------+
|  2020-05-13T09:50:36.000Z |  RHEL-7.9_HVM_BETA-20200422-x86_64-0-Hourly2-GP2  |  ami-038714142142a6a64 |
|  2020-09-18T07:51:03.000Z |  RHEL-7.9_HVM_GA-20200917-x86_64-0-Hourly2-GP2    |  ami-005b7876121b7244d |
|  2021-02-09T09:46:19.000Z |  RHEL-7.9_HVM-20210208-x86_64-0-Hourly2-GP2       |  ami-030e754805234517e |
+---------------------------+----------------------------------------------------+-----------------------+

Additional resources

7.4. Preparing the machine to run the playbook

Before you can add compute machines that use Red Hat Enterprise Linux as the operating system to an OpenShift Container Platform 4.6 cluster, you must prepare a machine to run the playbook from. This machine is not part of the cluster but must be able to access it.

Prerequisites

  • Install the OpenShift CLI (oc) on the machine that you run the playbook on.
  • Log in as a user with cluster-admin permission.

Procedure

  1. Ensure that the kubeconfig file for the cluster and the installation program that you used to install the cluster are on the machine. One way to accomplish this is to use the same machine that you used to install the cluster.
  2. Configure the machine to access all of the RHEL hosts that you plan to use as compute machines. You can use any method that your company allows, including a bastion with an SSH proxy or a VPN.
  3. Configure a user on the machine that you run the playbook on that has SSH access to all of the RHEL hosts.

    Important

    If you use SSH key-based authentication, you must manage the key with an SSH agent.

  4. If you have not already done so, register the machine with RHSM and attach a pool with an OpenShift subscription to it:

    1. Register the machine with RHSM:

      # subscription-manager register --username=<user_name> --password=<password>
    2. Pull the latest subscription data from RHSM:

      # subscription-manager refresh
    3. List the available subscriptions:

      # subscription-manager list --available --matches '*OpenShift*'
    4. In the output for the previous command, find the pool ID for an OpenShift Container Platform subscription and attach it:

      # subscription-manager attach --pool=<pool_id>
  5. Enable the repositories required by OpenShift Container Platform 4.6:

    # subscription-manager repos \
        --enable="rhel-7-server-rpms" \
        --enable="rhel-7-server-extras-rpms" \
        --enable="rhel-7-server-ansible-2.9-rpms" \
        --enable="rhel-7-server-ose-4.6-rpms"
  6. Install the required packages, including openshift-ansible:

    # yum install openshift-ansible openshift-clients jq

    The openshift-ansible package provides installation program utilities and pulls in other packages that you require to add a RHEL compute node to your cluster, such as Ansible, playbooks, and related configuration files. The openshift-clients provides the oc CLI, and the jq package improves the display of JSON output on your command line.

7.5. Preparing a RHEL compute node

Before you add a Red Hat Enterprise Linux (RHEL) machine to your OpenShift Container Platform cluster, you must register each host with Red Hat Subscription Manager (RHSM), attach an active OpenShift Container Platform subscription, and enable the required repositories.

  1. On each host, register with RHSM:

    # subscription-manager register --username=<user_name> --password=<password>
  2. Pull the latest subscription data from RHSM:

    # subscription-manager refresh
  3. List the available subscriptions:

    # subscription-manager list --available --matches '*OpenShift*'
  4. In the output for the previous command, find the pool ID for an OpenShift Container Platform subscription and attach it:

    # subscription-manager attach --pool=<pool_id>
  5. Disable all yum repositories:

    1. Disable all the enabled RHSM repositories:

      # subscription-manager repos --disable="*"
    2. List the remaining yum repositories and note their names under repo id, if any:

      # yum repolist
    3. Use yum-config-manager to disable the remaining yum repositories:

      # yum-config-manager --disable <repo_id>

      Alternatively, disable all repositories:

      # yum-config-manager --disable \*

      Note that this might take a few minutes if you have a large number of available repositories

  6. Enable only the repositories required by OpenShift Container Platform 4.6:

    # subscription-manager repos \
        --enable="rhel-7-server-rpms" \
        --enable="rhel-7-fast-datapath-rpms" \
        --enable="rhel-7-server-extras-rpms" \
        --enable="rhel-7-server-optional-rpms" \
        --enable="rhel-7-server-ose-4.6-rpms"
  7. Stop and disable firewalld on the host:

    # systemctl disable --now firewalld.service
    Note

    You must not enable firewalld later. If you do, you cannot access OpenShift Container Platform logs on the worker.

7.6. Attaching the role permissions to RHEL instance in AWS

Using the Amazon IAM console in your browser, you may select the needed roles and assign them to a worker node.

Procedure

  1. From the AWS IAM console, create your desired IAM role.
  2. Attach the IAM role to the desired worker node. The following permissions are required:

    • sts:AssumeRole
    • ec2:DescribeInstances
    • ec2:DescribeRegions

7.7. Tagging a RHEL worker node as owned or shared

A cluster uses the value of the kubernetes.io/cluster/<clusterid>,Value=(owned|shared) tag to determine the lifetime of the resources related to the AWS cluster.

  • The owned tag value should be added if the resource should be destroyed as part of destroying the cluster.
  • The shared tag value should be added if the resource continues to exist after the cluster has been destroyed. This tagging denotes that the cluster uses this resource, but there is a separate owner for the resource.

Procedure

  • With RHEL compute machines, the RHEL worker instance must be tagged with kubernetes.io/cluster/<clusterid>=owned or kubernetes.io/cluster/<cluster-id>=shared.
Note

Do not tag all existing security groups with the kubernetes.io/cluster/<name>,Value=<clusterid> tag, or the Elastic Load Balancing (ELB) will not be able to create a load balancer.

7.8. Adding a RHEL compute machine to your cluster

You can add compute machines that use Red Hat Enterprise Linux as the operating system to an OpenShift Container Platform 4.6 cluster.

Prerequisites

  • You installed the required packages and performed the necessary configuration on the machine that you run the playbook on.
  • You prepared the RHEL hosts for installation.

Procedure

Perform the following steps on the machine that you prepared to run the playbook:

  1. Create an Ansible inventory file that is named /<path>/inventory/hosts that defines your compute machine hosts and required variables:

    [all:vars]
    ansible_user=root 1
    #ansible_become=True 2
    
    openshift_kubeconfig_path="~/.kube/config" 3
    
    [new_workers] 4
    mycluster-rhel7-0.example.com
    mycluster-rhel7-1.example.com
    1
    Specify the user name that runs the Ansible tasks on the remote compute machines.
    2
    If you do not specify root for the ansible_user, you must set ansible_become to True and assign the user sudo permissions.
    3
    Specify the path and file name of the kubeconfig file for your cluster.
    4
    List each RHEL machine to add to your cluster. You must provide the fully-qualified domain name for each host. This name is the hostname that the cluster uses to access the machine, so set the correct public or private name to access the machine.
  2. Navigate to the Ansible playbook directory:

    $ cd /usr/share/ansible/openshift-ansible
  3. Run the playbook:

    $ ansible-playbook -i /<path>/inventory/hosts playbooks/scaleup.yml 1
    1
    For <path>, specify the path to the Ansible inventory file that you created.

7.9. Approving the certificate signing requests for your machines

When you add machines to a cluster, two pending certificate signing requests (CSRs) are generated for each machine that you added. You must confirm that these CSRs are approved or, if necessary, approve them yourself. The client requests must be approved first, followed by the server requests.

Prerequisites

  • You added machines to your cluster.

Procedure

  1. Confirm that the cluster recognizes the machines:

    $ oc get nodes

    Example output

    NAME      STATUS    ROLES   AGE  VERSION
    master-0  Ready     master  63m  v1.19.0
    master-1  Ready     master  63m  v1.19.0
    master-2  Ready     master  64m  v1.19.0
    worker-0  NotReady  worker  76s  v1.19.0
    worker-1  NotReady  worker  70s  v1.19.0

    The output lists all of the machines that you created.

    Note

    The preceding output might not include the compute nodes, also known as worker nodes, until some CSRs are approved.

  2. Review the pending CSRs and ensure that you see the client requests with the Pending or Approved status for each machine that you added to the cluster:

    $ oc get csr

    Example output

    NAME        AGE     REQUESTOR                                                                   CONDITION
    csr-8b2br   15m     system:serviceaccount:openshift-machine-config-operator:node-bootstrapper   Pending
    csr-8vnps   15m     system:serviceaccount:openshift-machine-config-operator:node-bootstrapper   Pending
    ...

    In this example, two machines are joining the cluster. You might see more approved CSRs in the list.

  3. If the CSRs were not approved, after all of the pending CSRs for the machines you added are in Pending status, approve the CSRs for your cluster machines:

    Note

    Because the CSRs rotate automatically, approve your CSRs within an hour of adding the machines to the cluster. If you do not approve them within an hour, the certificates will rotate, and more than two certificates will be present for each node. You must approve all of these certificates. Once the client CSR is approved, the Kubelet creates a secondary CSR for the serving certificate, which requires manual approval. Then, subsequent serving certificate renewal requests are automatically approved by the machine-approver if the Kubelet requests a new certificate with identical parameters.

    Note

    For clusters running on platforms that are not machine API enabled, such as bare metal and other user-provisioned infrastructure, you must implement a method of automatically approving the kubelet serving certificate requests (CSRs). If a request is not approved, then the oc exec, oc rsh, and oc logs commands cannot succeed, because a serving certificate is required when the API server connects to the kubelet. Any operation that contacts the Kubelet endpoint requires this certificate approval to be in place. The method must watch for new CSRs, confirm that the CSR was submitted by the node-bootstrapper service account in the system:node or system:admin groups, and confirm the identity of the node.

    • To approve them individually, run the following command for each valid CSR:

      $ oc adm certificate approve <csr_name> 1
      1
      <csr_name> is the name of a CSR from the list of current CSRs.
    • To approve all pending CSRs, run the following command:

      $ oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs --no-run-if-empty oc adm certificate approve
      Note

      Some Operators might not become available until some CSRs are approved.

  4. Now that your client requests are approved, you must review the server requests for each machine that you added to the cluster:

    $ oc get csr

    Example output

    NAME        AGE     REQUESTOR                                                                   CONDITION
    csr-bfd72   5m26s   system:node:ip-10-0-50-126.us-east-2.compute.internal                       Pending
    csr-c57lv   5m26s   system:node:ip-10-0-95-157.us-east-2.compute.internal                       Pending
    ...

  5. If the remaining CSRs are not approved, and are in the Pending status, approve the CSRs for your cluster machines:

    • To approve them individually, run the following command for each valid CSR:

      $ oc adm certificate approve <csr_name> 1
      1
      <csr_name> is the name of a CSR from the list of current CSRs.
    • To approve all pending CSRs, run the following command:

      $ oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs oc adm certificate approve
  6. After all client and server CSRs have been approved, the machines have the Ready status. Verify this by running the following command:

    $ oc get nodes

    Example output

    NAME      STATUS    ROLES   AGE  VERSION
    master-0  Ready     master  73m  v1.20.0
    master-1  Ready     master  73m  v1.20.0
    master-2  Ready     master  74m  v1.20.0
    worker-0  Ready     worker  11m  v1.20.0
    worker-1  Ready     worker  11m  v1.20.0

    Note

    It can take a few minutes after approval of the server CSRs for the machines to transition to the Ready status.

Additional information

7.10. Required parameters for the Ansible hosts file

You must define the following parameters in the Ansible hosts file before you add Red Hat Enterprise Linux (RHEL) compute machines to your cluster.

ParamterDescriptionValues

ansible_user

The SSH user that allows SSH-based authentication without requiring a password. If you use SSH key-based authentication, then you must manage the key with an SSH agent.

A user name on the system. The default value is root.

ansible_become

If the values of ansible_user is not root, you must set ansible_become to True, and the user that you specify as the ansible_user must be configured for passwordless sudo access.

True. If the value is not True, do not specify and define this parameter.

openshift_kubeconfig_path

Specifies a path and file name to a local directory that contains the kubeconfig file for your cluster.

The path and name of the configuration file.

7.10.1. Optional: Removing RHCOS compute machines from a cluster

After you add the Red Hat Enterprise Linux (RHEL) compute machines to your cluster, you can optionally remove the Red Hat Enterprise Linux CoreOS (RHCOS) compute machines to free up resources.

Prerequisites

  • You have added RHEL compute machines to your cluster.

Procedure

  1. View the list of machines and record the node names of the RHCOS compute machines:

    $ oc get nodes -o wide
  2. For each RHCOS compute machine, delete the node:

    1. Mark the node as unschedulable by running the oc adm cordon command:

      $ oc adm cordon <node_name> 1
      1
      Specify the node name of one of the RHCOS compute machines.
    2. Drain all the pods from the node:

      $ oc adm drain <node_name> --force --delete-local-data --ignore-daemonsets 1
      1
      Specify the node name of the RHCOS compute machine that you isolated.
    3. Delete the node:

      $ oc delete nodes <node_name> 1
      1
      Specify the node name of the RHCOS compute machine that you drained.
  3. Review the list of compute machines to ensure that only the RHEL nodes remain:

    $ oc get nodes -o wide
  4. Remove the RHCOS machines from the load balancer for your cluster’s compute machines. You can delete the virtual machines or reimage the physical hardware for the RHCOS compute machines.

Chapter 8. Adding more RHEL compute machines to an OpenShift Container Platform cluster

If your OpenShift Container Platform cluster already includes Red Hat Enterprise Linux (RHEL) compute machines, which are also known as worker machines, you can add more RHEL compute machines to it.

8.1. About adding RHEL compute nodes to a cluster

In OpenShift Container Platform 4.6, you have the option of using Red Hat Enterprise Linux (RHEL) machines as compute machines, which are also known as worker machines, in your cluster if you use a user-provisioned infrastructure installation. You must use Red Hat Enterprise Linux CoreOS (RHCOS) machines for the control plane, or master, machines in your cluster.

As with all installations that use user-provisioned infrastructure, if you choose to use RHEL compute machines in your cluster, you take responsibility for all operating system life cycle management and maintenance, including performing system updates, applying patches, and completing all other required tasks.

Important

Because removing OpenShift Container Platform from a machine in the cluster requires destroying the operating system, you must use dedicated hardware for any RHEL machines that you add to the cluster.

Important

Swap memory is disabled on all RHEL machines that you add to your OpenShift Container Platform cluster. You cannot enable swap memory on these machines.

You must add any RHEL compute machines to the cluster after you initialize the control plane.

8.2. System requirements for RHEL compute nodes

The Red Hat Enterprise Linux (RHEL) compute, or worker, machine hosts in your OpenShift Container Platform environment must meet the following minimum hardware specifications and system-level requirements:

  • You must have an active OpenShift Container Platform subscription on your Red Hat account. If you do not, contact your sales representative for more information.
  • Production environments must provide compute machines to support your expected workloads. As a cluster administrator, you must calculate the expected workload and add about 10 percent for overhead. For production environments, allocate enough resources so that a node host failure does not affect your maximum capacity.
  • Each system must meet the following hardware requirements:

    • Physical or virtual system, or an instance running on a public or private IaaS.
    • Base OS: RHEL 7.9 with "Minimal" installation option.

      Important

      Adding RHEL 7 compute machines to an OpenShift Container Platform cluster is deprecated. Deprecated functionality is still included in OpenShift Container Platform and continues to be supported; however, it will be removed in a future release of this product and is not recommended for new deployments.

      In addition, you must not upgrade your compute machines to RHEL 8 because support is not available in this release.

      For the most recent list of major functionality that has been deprecated or removed within OpenShift Container Platform, refer to the Deprecated and removed features section of the OpenShift Container Platform release notes.

    • If you deployed OpenShift Container Platform in FIPS mode, you must enable FIPS on the RHEL machine before you boot it. See Enabling FIPS Mode in the RHEL 7 documentation.
Important

The use of FIPS Validated / Modules in Process cryptographic libraries is only supported on OpenShift Container Platform deployments on the x86_64 architecture.

  • NetworkManager 1.0 or later.
  • 1 vCPU.
  • Minimum 8 GB RAM.
  • Minimum 15 GB hard disk space for the file system containing /var/.
  • Minimum 1 GB hard disk space for the file system containing /usr/local/bin/.
  • Minimum 1 GB hard disk space for the file system containing the system’s temporary directory. The system’s temporary directory is determined according to the rules defined in the tempfile module in Python’s standard library.

    • Each system must meet any additional requirements for your system provider. For example, if you installed your cluster on VMware vSphere, your disks must be configured according to its storage guidelines and the disk.enableUUID=true attribute must be set.
    • Each system must be able to access the cluster’s API endpoints by using DNS-resolvable hostnames. Any network security access control that is in place must allow the system access to the cluster’s API service endpoints.

8.2.1. Certificate signing requests management

Because your cluster has limited access to automatic machine management when you use infrastructure that you provision, you must provide a mechanism for approving cluster certificate signing requests (CSRs) after installation. The kube-controller-manager only approves the kubelet client CSRs. The machine-approver cannot guarantee the validity of a serving certificate that is requested by using kubelet credentials because it cannot confirm that the correct machine issued the request. You must determine and implement a method of verifying the validity of the kubelet serving certificate requests and approving them.

8.3. Preparing an image for your cloud

Amazon Machine Images (AMI) are required since various image formats cannot be used directly by AWS. You may use the AMIs that Red Hat has provided, or you can manually import your own images. The AMI must exist before the EC2 instance can be provisioned. You must list the AMI IDs so that the correct RHEL version needed for the compute machines is selected.

8.3.1. Listing latest available RHEL images on AWS

AMI IDs correspond to native boot images for AWS. Because an AMI must exist before the EC2 instance is provisioned, you will need to know the AMI ID before configuration. The AWS Command Line Interface (CLI) is used to list the available Red Hat Enterprise Linux (RHEL) image IDs.

Prerequisites

  • You have installed the AWS CLI.

Procedure

  • Use this command to list RHEL 7.9 Amazon Machine Images (AMI):

    $ aws ec2 describe-images --owners 309956199498 \ 1
    --query 'sort_by(Images, &CreationDate)[*].[CreationDate,Name,ImageId]' \ 2
    --filters "Name=name,Values=RHEL-7.9*" \ 3
    --region us-east-1 \ 4
    --output table 5
    1
    The --owners command option shows Red Hat images based on the account ID 309956199498.
    Important

    This account ID is required to display AMI IDs for images that are provided by Red Hat.

    2
    The --query command option sets how the images are sorted with the parameters 'sort_by(Images, &CreationDate)[*].[CreationDate,Name,ImageId]'. In this case, the images are sorted by the creation date, and the table is structured to show the creation date, the name of the image, and the AMI IDs.
    3
    The --filter command option sets which version of RHEL is shown. In this example, since the filter is set by "Name=name,Values=RHEL-7.9*", then RHEL 7.9 AMIs are shown.
    4
    The --region command option sets where the region where an AMI is stored.
    5
    The --output command option sets how the results are displayed.
Note

When creating a RHEL compute machine for AWS, ensure that the AMI is RHEL 7.9.

Example output

----------------------------------------------------------------------------------------------------------
|                                             DescribeImages                                             |
+---------------------------+----------------------------------------------------+-----------------------+
|  2020-05-13T09:50:36.000Z |  RHEL-7.9_HVM_BETA-20200422-x86_64-0-Hourly2-GP2  |  ami-038714142142a6a64 |
|  2020-09-18T07:51:03.000Z |  RHEL-7.9_HVM_GA-20200917-x86_64-0-Hourly2-GP2    |  ami-005b7876121b7244d |
|  2021-02-09T09:46:19.000Z |  RHEL-7.9_HVM-20210208-x86_64-0-Hourly2-GP2       |  ami-030e754805234517e |
+---------------------------+----------------------------------------------------+-----------------------+

Additional resources

8.4. Preparing a RHEL compute node

Before you add a Red Hat Enterprise Linux (RHEL) machine to your OpenShift Container Platform cluster, you must register each host with Red Hat Subscription Manager (RHSM), attach an active OpenShift Container Platform subscription, and enable the required repositories.

  1. On each host, register with RHSM:

    # subscription-manager register --username=<user_name> --password=<password>
  2. Pull the latest subscription data from RHSM:

    # subscription-manager refresh
  3. List the available subscriptions:

    # subscription-manager list --available --matches '*OpenShift*'
  4. In the output for the previous command, find the pool ID for an OpenShift Container Platform subscription and attach it:

    # subscription-manager attach --pool=<pool_id>
  5. Disable all yum repositories:

    1. Disable all the enabled RHSM repositories:

      # subscription-manager repos --disable="*"
    2. List the remaining yum repositories and note their names under repo id, if any:

      # yum repolist
    3. Use yum-config-manager to disable the remaining yum repositories:

      # yum-config-manager --disable <repo_id>

      Alternatively, disable all repositories:

      # yum-config-manager --disable \*

      Note that this might take a few minutes if you have a large number of available repositories

  6. Enable only the repositories required by OpenShift Container Platform 4.6:

    # subscription-manager repos \
        --enable="rhel-7-server-rpms" \
        --enable="rhel-7-fast-datapath-rpms" \
        --enable="rhel-7-server-extras-rpms" \
        --enable="rhel-7-server-optional-rpms" \
        --enable="rhel-7-server-ose-4.6-rpms"
  7. Stop and disable firewalld on the host:

    # systemctl disable --now firewalld.service
    Note

    You must not enable firewalld later. If you do, you cannot access OpenShift Container Platform logs on the worker.

8.5. Attaching the role permissions to RHEL instance in AWS

Using the Amazon IAM console in your browser, you may select the needed roles and assign them to a worker node.

Procedure

  1. From the AWS IAM console, create your desired IAM role.
  2. Attach the IAM role to the desired worker node. The following permissions are required:

    • sts:AssumeRole
    • ec2:DescribeInstances
    • ec2:DescribeRegions

8.6. Tagging a RHEL worker node as owned or shared

A cluster uses the value of the kubernetes.io/cluster/<clusterid>,Value=(owned|shared) tag to determine the lifetime of the resources related to the AWS cluster.

  • The owned tag value should be added if the resource should be destroyed as part of destroying the cluster.
  • The shared tag value should be added if the resource continues to exist after the cluster has been destroyed. This tagging denotes that the cluster uses this resource, but there is a separate owner for the resource.

Procedure

  • With RHEL compute machines, the RHEL worker instance must be tagged with kubernetes.io/cluster/<clusterid>=owned or kubernetes.io/cluster/<cluster-id>=shared.
Note

Do not tag all existing security groups with the kubernetes.io/cluster/<name>,Value=<clusterid> tag, or the Elastic Load Balancing (ELB) will not be able to create a load balancer.

8.7. Adding more RHEL compute machines to your cluster

You can add more compute machines that use Red Hat Enterprise Linux (RHEL) as the operating system to an OpenShift Container Platform 4.6 cluster.

Prerequisites

  • Your OpenShift Container Platform cluster already contains RHEL compute nodes.
  • The hosts file that you used to add the first RHEL compute machines to your cluster is on the machine that you use the run the playbook.
  • The machine that you run the playbook on must be able to access all of the RHEL hosts. You can use any method that your company allows, including a bastion with an SSH proxy or a VPN.
  • The kubeconfig file for the cluster and the installation program that you used to install the cluster are on the machine that you use the run the playbook.
  • You must prepare the RHEL hosts for installation.
  • Configure a user on the machine that you run the playbook on that has SSH access to all of the RHEL hosts.
  • If you use SSH key-based authentication, you must manage the key with an SSH agent.
  • Install the OpenShift CLI (oc) on the machine that you run the playbook on.

Procedure

  1. Open the Ansible inventory file at /<path>/inventory/hosts that defines your compute machine hosts and required variables.
  2. Rename the [new_workers] section of the file to [workers].
  3. Add a [new_workers] section to the file and define the fully-qualified domain names for each new host. The file resembles the following example:

    [all:vars]
    ansible_user=root
    #ansible_become=True
    
    openshift_kubeconfig_path="~/.kube/config"
    
    [workers]
    mycluster-rhel7-0.example.com
    mycluster-rhel7-1.example.com
    
    [new_workers]
    mycluster-rhel7-2.example.com
    mycluster-rhel7-3.example.com

    In this example, the mycluster-rhel7-0.example.com and mycluster-rhel7-1.example.com machines are in the cluster and you add the mycluster-rhel7-2.example.com and mycluster-rhel7-3.example.com machines.

  4. Navigate to the Ansible playbook directory:

    $ cd /usr/share/ansible/openshift-ansible
  5. Run the scaleup playbook:

    $ ansible-playbook -i /<path>/inventory/hosts playbooks/scaleup.yml 1
    1
    For <path>, specify the path to the Ansible inventory file that you created.

8.8. Approving the certificate signing requests for your machines

When you add machines to a cluster, two pending certificate signing requests (CSRs) are generated for each machine that you added. You must confirm that these CSRs are approved or, if necessary, approve them yourself. The client requests must be approved first, followed by the server requests.

Prerequisites

  • You added machines to your cluster.

Procedure

  1. Confirm that the cluster recognizes the machines:

    $ oc get nodes

    Example output

    NAME      STATUS    ROLES   AGE  VERSION
    master-0  Ready     master  63m  v1.19.0
    master-1  Ready     master  63m  v1.19.0
    master-2  Ready     master  64m  v1.19.0
    worker-0  NotReady  worker  76s  v1.19.0
    worker-1  NotReady  worker  70s  v1.19.0

    The output lists all of the machines that you created.

    Note

    The preceding output might not include the compute nodes, also known as worker nodes, until some CSRs are approved.

  2. Review the pending CSRs and ensure that you see the client requests with the Pending or Approved status for each machine that you added to the cluster:

    $ oc get csr

    Example output

    NAME        AGE     REQUESTOR                                                                   CONDITION
    csr-8b2br   15m     system:serviceaccount:openshift-machine-config-operator:node-bootstrapper   Pending
    csr-8vnps   15m     system:serviceaccount:openshift-machine-config-operator:node-bootstrapper   Pending
    ...

    In this example, two machines are joining the cluster. You might see more approved CSRs in the list.

  3. If the CSRs were not approved, after all of the pending CSRs for the machines you added are in Pending status, approve the CSRs for your cluster machines:

    Note

    Because the CSRs rotate automatically, approve your CSRs within an hour of adding the machines to the cluster. If you do not approve them within an hour, the certificates will rotate, and more than two certificates will be present for each node. You must approve all of these certificates. Once the client CSR is approved, the Kubelet creates a secondary CSR for the serving certificate, which requires manual approval. Then, subsequent serving certificate renewal requests are automatically approved by the machine-approver if the Kubelet requests a new certificate with identical parameters.

    Note

    For clusters running on platforms that are not machine API enabled, such as bare metal and other user-provisioned infrastructure, you must implement a method of automatically approving the kubelet serving certificate requests (CSRs). If a request is not approved, then the oc exec, oc rsh, and oc logs commands cannot succeed, because a serving certificate is required when the API server connects to the kubelet. Any operation that contacts the Kubelet endpoint requires this certificate approval to be in place. The method must watch for new CSRs, confirm that the CSR was submitted by the node-bootstrapper service account in the system:node or system:admin groups, and confirm the identity of the node.

    • To approve them individually, run the following command for each valid CSR:

      $ oc adm certificate approve <csr_name> 1
      1
      <csr_name> is the name of a CSR from the list of current CSRs.
    • To approve all pending CSRs, run the following command:

      $ oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs --no-run-if-empty oc adm certificate approve
      Note

      Some Operators might not become available until some CSRs are approved.

  4. Now that your client requests are approved, you must review the server requests for each machine that you added to the cluster:

    $ oc get csr

    Example output

    NAME        AGE     REQUESTOR                                                                   CONDITION
    csr-bfd72   5m26s   system:node:ip-10-0-50-126.us-east-2.compute.internal                       Pending
    csr-c57lv   5m26s   system:node:ip-10-0-95-157.us-east-2.compute.internal                       Pending
    ...

  5. If the remaining CSRs are not approved, and are in the Pending status, approve the CSRs for your cluster machines:

    • To approve them individually, run the following command for each valid CSR:

      $ oc adm certificate approve <csr_name> 1
      1
      <csr_name> is the name of a CSR from the list of current CSRs.
    • To approve all pending CSRs, run the following command:

      $ oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs oc adm certificate approve
  6. After all client and server CSRs have been approved, the machines have the Ready status. Verify this by running the following command:

    $ oc get nodes

    Example output

    NAME      STATUS    ROLES   AGE  VERSION
    master-0  Ready     master  73m  v1.20.0
    master-1  Ready     master  73m  v1.20.0
    master-2  Ready     master  74m  v1.20.0
    worker-0  Ready     worker  11m  v1.20.0
    worker-1  Ready     worker  11m  v1.20.0

    Note

    It can take a few minutes after approval of the server CSRs for the machines to transition to the Ready status.

Additional information

8.9. Required parameters for the Ansible hosts file

You must define the following parameters in the Ansible hosts file before you add Red Hat Enterprise Linux (RHEL) compute machines to your cluster.

ParamterDescriptionValues

ansible_user

The SSH user that allows SSH-based authentication without requiring a password. If you use SSH key-based authentication, then you must manage the key with an SSH agent.

A user name on the system. The default value is root.

ansible_become

If the values of ansible_user is not root, you must set ansible_become to True, and the user that you specify as the ansible_user must be configured for passwordless sudo access.

True. If the value is not True, do not specify and define this parameter.

openshift_kubeconfig_path

Specifies a path and file name to a local directory that contains the kubeconfig file for your cluster.

The path and name of the configuration file.

Chapter 9. User-provisioned infrastructure

9.1. Adding compute machines to AWS by using CloudFormation templates

You can add more compute machines to your OpenShift Container Platform cluster on Amazon Web Services (AWS) that you created by using the sample CloudFormation templates.

9.1.1. Prerequisites

  • You installed your cluster on AWS by using the provided AWS CloudFormation templates.
  • You have the JSON file and CloudFormation template that you used to create the compute machines during cluster installation. If you do not have these files, you must recreate them by following the instructions in the installation procedure.

9.1.2. Adding more compute machines to your AWS cluster by using CloudFormation templates

You can add more compute machines to your OpenShift Container Platform cluster on Amazon Web Services (AWS) that you created by using the sample CloudFormation templates.

Important

The CloudFormation template creates a stack that represents one compute machine. You must create a stack for each compute machine.

Note

If you do not use the provided CloudFormation template to create your compute nodes, you must review the provided information and manually create the infrastructure. If your cluster does not initialize correctly, you might have to contact Red Hat support with your installation logs.

Prerequisites

  • You installed an OpenShift Container Platform cluster by using CloudFormation templates and have access to the JSON file and CloudFormation template that you used to create the compute machines during cluster installation.
  • You installed the AWS CLI.

Procedure

  1. Create another compute stack.

    1. Launch the template:

      $ aws cloudformation create-stack --stack-name <name> \ 1
           --template-body file://<template>.yaml \ 2
           --parameters file://<parameters>.json 3
      1
      <name> is the name for the CloudFormation stack, such as cluster-workers. You must provide the name of this stack if you remove the cluster.
      2
      <template> is the relative path to and name of the CloudFormation template YAML file that you saved.
      3
      <parameters> is the relative path to and name of the CloudFormation parameters JSON file.
    2. Confirm that the template components exist:

      $ aws cloudformation describe-stacks --stack-name <name>
  2. Continue to create compute stacks until you have created enough compute machines for your cluster.

9.1.3. Approving the certificate signing requests for your machines

When you add machines to a cluster, two pending certificate signing requests (CSRs) are generated for each machine that you added. You must confirm that these CSRs are approved or, if necessary, approve them yourself. The client requests must be approved first, followed by the server requests.

Prerequisites

  • You added machines to your cluster.

Procedure

  1. Confirm that the cluster recognizes the machines:

    $ oc get nodes

    Example output

    NAME      STATUS    ROLES   AGE  VERSION
    master-0  Ready     master  63m  v1.19.0
    master-1  Ready     master  63m  v1.19.0
    master-2  Ready     master  64m  v1.19.0
    worker-0  NotReady  worker  76s  v1.19.0
    worker-1  NotReady  worker  70s  v1.19.0

    The output lists all of the machines that you created.

    Note

    The preceding output might not include the compute nodes, also known as worker nodes, until some CSRs are approved.

  2. Review the pending CSRs and ensure that you see the client requests with the Pending or Approved status for each machine that you added to the cluster:

    $ oc get csr

    Example output

    NAME        AGE     REQUESTOR                                                                   CONDITION
    csr-8b2br   15m     system:serviceaccount:openshift-machine-config-operator:node-bootstrapper   Pending
    csr-8vnps   15m     system:serviceaccount:openshift-machine-config-operator:node-bootstrapper   Pending
    ...

    In this example, two machines are joining the cluster. You might see more approved CSRs in the list.

  3. If the CSRs were not approved, after all of the pending CSRs for the machines you added are in Pending status, approve the CSRs for your cluster machines:

    Note

    Because the CSRs rotate automatically, approve your CSRs within an hour of adding the machines to the cluster. If you do not approve them within an hour, the certificates will rotate, and more than two certificates will be present for each node. You must approve all of these certificates. Once the client CSR is approved, the Kubelet creates a secondary CSR for the serving certificate, which requires manual approval. Then, subsequent serving certificate renewal requests are automatically approved by the machine-approver if the Kubelet requests a new certificate with identical parameters.

    Note

    For clusters running on platforms that are not machine API enabled, such as bare metal and other user-provisioned infrastructure, you must implement a method of automatically approving the kubelet serving certificate requests (CSRs). If a request is not approved, then the oc exec, oc rsh, and oc logs commands cannot succeed, because a serving certificate is required when the API server connects to the kubelet. Any operation that contacts the Kubelet endpoint requires this certificate approval to be in place. The method must watch for new CSRs, confirm that the CSR was submitted by the node-bootstrapper service account in the system:node or system:admin groups, and confirm the identity of the node.

    • To approve them individually, run the following command for each valid CSR:

      $ oc adm certificate approve <csr_name> 1
      1
      <csr_name> is the name of a CSR from the list of current CSRs.
    • To approve all pending CSRs, run the following command:

      $ oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs --no-run-if-empty oc adm certificate approve
      Note

      Some Operators might not become available until some CSRs are approved.

  4. Now that your client requests are approved, you must review the server requests for each machine that you added to the cluster:

    $ oc get csr

    Example output

    NAME        AGE     REQUESTOR                                                                   CONDITION
    csr-bfd72   5m26s   system:node:ip-10-0-50-126.us-east-2.compute.internal                       Pending
    csr-c57lv   5m26s   system:node:ip-10-0-95-157.us-east-2.compute.internal                       Pending
    ...

  5. If the remaining CSRs are not approved, and are in the Pending status, approve the CSRs for your cluster machines:

    • To approve them individually, run the following command for each valid CSR:

      $ oc adm certificate approve <csr_name> 1
      1
      <csr_name> is the name of a CSR from the list of current CSRs.
    • To approve all pending CSRs, run the following command:

      $ oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs oc adm certificate approve
  6. After all client and server CSRs have been approved, the machines have the Ready status. Verify this by running the following command:

    $ oc get nodes

    Example output

    NAME      STATUS    ROLES   AGE  VERSION
    master-0  Ready     master  73m  v1.20.0
    master-1  Ready     master  73m  v1.20.0
    master-2  Ready     master  74m  v1.20.0
    worker-0  Ready     worker  11m  v1.20.0
    worker-1  Ready     worker  11m  v1.20.0

    Note

    It can take a few minutes after approval of the server CSRs for the machines to transition to the Ready status.

Additional information

9.2. Adding compute machines to vSphere

You can add more compute machines to your OpenShift Container Platform cluster on VMware vSphere.

9.2.1. Prerequisites

  • You installed a cluster on vSphere.
  • You have installation media and Red Hat Enterprise Linux CoreOS (RHCOS) images that you used to create your cluster. If you do not have these files, you must obtain them by following the instructions in the installation procedure.
Important

If you do not have access to the Red Hat Enterprise Linux CoreOS (RHCOS) images that were used to create your cluster, you can add more compute machines to your OpenShift Container Platform cluster with newer versions of Red Hat Enterprise Linux CoreOS (RHCOS) images. For instructions, see Adding new nodes to UPI cluster fails after upgrading to OpenShift 4.6+.

9.2.2. Creating more Red Hat Enterprise Linux CoreOS (RHCOS) machines in vSphere

You can create more compute machines for your cluster that uses user-provisioned infrastructure on VMware vSphere.

Prerequisites

  • Obtain the base64-encoded Ignition file for your compute machines.
  • You have access to the vSphere template that you created for your cluster.

Procedure

  1. After the template deploys, deploy a VM for a machine in the cluster.

    1. Right-click the template’s name and click CloneClone to Virtual Machine.
    2. On the Select a name and folder tab, specify a name for the VM. You might include the machine type in the name, such as compute-1.
    3. On the Select a name and folder tab, select the name of the folder that you created for the cluster.
    4. On the Select a compute resource tab, select the name of a host in your datacenter.
    5. Optional: On the Select storage tab, customize the storage options.
    6. On the Select clone options, select Customize this virtual machine’s hardware.
    7. On the Customize hardware tab, click VM OptionsAdvanced.

      • From the Latency Sensitivity list, select High.
      • Click Edit Configuration, and on the Configuration Parameters window, click Add Configuration Params. Define the following parameter names and values:

        • guestinfo.ignition.config.data: Paste the contents of the base64-encoded compute Ignition config file for this machine type.
        • guestinfo.ignition.config.data.encoding: Specify base64.
        • disk.EnableUUID: Specify TRUE.
    8. In the Virtual Hardware panel of the Customize hardware tab, modify the specified values as required. Ensure that the amount of RAM, CPU, and disk storage meets the minimum requirements for the machine type. Also, make sure to select the correct network under Add network adapter if there are multiple networks available.
    9. Complete the configuration and power on the VM.
  2. Continue to create more compute machines for your cluster.

9.2.3. Approving the certificate signing requests for your machines

When you add machines to a cluster, two pending certificate signing requests (CSRs) are generated for each machine that you added. You must confirm that these CSRs are approved or, if necessary, approve them yourself. The client requests must be approved first, followed by the server requests.

Prerequisites

  • You added machines to your cluster.

Procedure

  1. Confirm that the cluster recognizes the machines:

    $ oc get nodes

    Example output

    NAME      STATUS    ROLES   AGE  VERSION
    master-0  Ready     master  63m  v1.19.0
    master-1  Ready     master  63m  v1.19.0
    master-2  Ready     master  64m  v1.19.0
    worker-0  NotReady  worker  76s  v1.19.0
    worker-1  NotReady  worker  70s  v1.19.0

    The output lists all of the machines that you created.

    Note

    The preceding output might not include the compute nodes, also known as worker nodes, until some CSRs are approved.

  2. Review the pending CSRs and ensure that you see the client requests with the Pending or Approved status for each machine that you added to the cluster:

    $ oc get csr

    Example output

    NAME        AGE     REQUESTOR                                                                   CONDITION
    csr-8b2br   15m     system:serviceaccount:openshift-machine-config-operator:node-bootstrapper   Pending
    csr-8vnps   15m     system:serviceaccount:openshift-machine-config-operator:node-bootstrapper   Pending
    ...

    In this example, two machines are joining the cluster. You might see more approved CSRs in the list.

  3. If the CSRs were not approved, after all of the pending CSRs for the machines you added are in Pending status, approve the CSRs for your cluster machines:

    Note

    Because the CSRs rotate automatically, approve your CSRs within an hour of adding the machines to the cluster. If you do not approve them within an hour, the certificates will rotate, and more than two certificates will be present for each node. You must approve all of these certificates. Once the client CSR is approved, the Kubelet creates a secondary CSR for the serving certificate, which requires manual approval. Then, subsequent serving certificate renewal requests are automatically approved by the machine-approver if the Kubelet requests a new certificate with identical parameters.

    Note

    For clusters running on platforms that are not machine API enabled, such as bare metal and other user-provisioned infrastructure, you must implement a method of automatically approving the kubelet serving certificate requests (CSRs). If a request is not approved, then the oc exec, oc rsh, and oc logs commands cannot succeed, because a serving certificate is required when the API server connects to the kubelet. Any operation that contacts the Kubelet endpoint requires this certificate approval to be in place. The method must watch for new CSRs, confirm that the CSR was submitted by the node-bootstrapper service account in the system:node or system:admin groups, and confirm the identity of the node.

    • To approve them individually, run the following command for each valid CSR:

      $ oc adm certificate approve <csr_name> 1
      1
      <csr_name> is the name of a CSR from the list of current CSRs.
    • To approve all pending CSRs, run the following command:

      $ oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs --no-run-if-empty oc adm certificate approve
      Note

      Some Operators might not become available until some CSRs are approved.

  4. Now that your client requests are approved, you must review the server requests for each machine that you added to the cluster:

    $ oc get csr

    Example output

    NAME        AGE     REQUESTOR                                                                   CONDITION
    csr-bfd72   5m26s   system:node:ip-10-0-50-126.us-east-2.compute.internal                       Pending
    csr-c57lv   5m26s   system:node:ip-10-0-95-157.us-east-2.compute.internal                       Pending
    ...

  5. If the remaining CSRs are not approved, and are in the Pending status, approve the CSRs for your cluster machines:

    • To approve them individually, run the following command for each valid CSR:

      $ oc adm certificate approve <csr_name> 1
      1
      <csr_name> is the name of a CSR from the list of current CSRs.
    • To approve all pending CSRs, run the following command:

      $ oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs oc adm certificate approve
  6. After all client and server CSRs have been approved, the machines have the Ready status. Verify this by running the following command:

    $ oc get nodes

    Example output

    NAME      STATUS    ROLES   AGE  VERSION
    master-0  Ready     master  73m  v1.20.0
    master-1  Ready     master  73m  v1.20.0
    master-2  Ready     master  74m  v1.20.0
    worker-0  Ready     worker  11m  v1.20.0
    worker-1  Ready     worker  11m  v1.20.0

    Note

    It can take a few minutes after approval of the server CSRs for the machines to transition to the Ready status.

Additional information

9.3. Adding compute machines to bare metal

You can add more compute machines to your OpenShift Container Platform cluster on bare metal.

9.3.1. Prerequisites

Important

If you do not have access to the Red Hat Enterprise Linux CoreOS (RHCOS) images that were used to create your cluster, you can add more compute machines to your OpenShift Container Platform cluster with newer versions of Red Hat Enterprise Linux CoreOS (RHCOS) images. For instructions, see Adding new nodes to UPI cluster fails after upgrading to OpenShift 4.6+.

9.3.2. Creating Red Hat Enterprise Linux CoreOS (RHCOS) machines

Before you add more compute machines to a cluster that you installed on bare metal infrastructure, you must create RHCOS machines for it to use. You can either use an ISO image or network PXE booting to create the machines.

9.3.2.1. Creating more RHCOS machines using an ISO image

You can create more Red Hat Enterprise Linux CoreOS (RHCOS) compute machines for your bare metal cluster by using an ISO image to create the machines.

Prerequisites

  • Obtain the URL of the Ignition config file for the compute machines for your cluster. You uploaded this file to your HTTP server during installation.

Procedure

  1. Use the ISO file to install RHCOS on more compute machines. Use the same method that you used when you created machines before you installed the cluster:

    • Burn the ISO image to a disk and boot it directly.
    • Use ISO redirection with a LOM interface.
  2. After the instance boots, press the TAB or E key to edit the kernel command line.
  3. Add the parameters to the kernel command line:

    coreos.inst.install_dev=sda 1
    coreos.inst.ignition_url=http://example.com/worker.ign 2
    1
    Specify the block device of the system to install to.
    2
    Specify the URL of the compute Ignition config file. Only HTTP and HTTPS protocols are supported.
  4. Press Enter to complete the installation. After RHCOS installs, the system reboots. After the system reboots, it applies the Ignition config file that you specified.
  5. Continue to create more compute machines for your cluster.

9.3.2.2. Creating more RHCOS machines by PXE or iPXE booting

You can create more Red Hat Enterprise Linux CoreOS (RHCOS) compute machines for your bare metal cluster by using PXE or iPXE booting.

Prerequisites

  • Obtain the URL of the Ignition config file for the compute machines for your cluster. You uploaded this file to your HTTP server during installation.
  • Obtain the URLs of the RHCOS ISO image, compressed metal BIOS, kernel, and initramfs files that you uploaded to your HTTP server during cluster installation.
  • You have access to the PXE booting infrastructure that you used to create the machines for your OpenShift Container Platform cluster during installation. The machines must boot from their local disks after RHCOS is installed on them.
  • If you use UEFI, you have access to the grub.conf file that you modified during OpenShift Container Platform installation.

Procedure

  1. Confirm that your PXE or iPXE installation for the RHCOS images is correct.

    • For PXE:

      DEFAULT pxeboot
      TIMEOUT 20
      PROMPT 0
      LABEL pxeboot
          KERNEL http://<HTTP_server>/rhcos-<version>-live-kernel-<architecture> 1
          APPEND initrd=http://<HTTP_server>/rhcos-<version>-live-initramfs.<architecture>.img coreos.inst.install_dev=/dev/sda coreos.inst.ignition_url=http://<HTTP_server>/worker.ign coreos.live.rootfs_url=http://<HTTP_server>/rhcos-<version>-live-rootfs.<architecture>.img 2
      1
      Specify the location of the live kernel file that you uploaded to your HTTP server.
      2
      Specify locations of the RHCOS files that you uploaded to your HTTP server. The initrd parameter value is the location of the live initramfs file, the coreos.inst.ignition_url parameter value is the location of the worker Ignition config file, and the coreos.live.rootfs_url parameter value is the location of the live rootfs file. The coreos.inst.ignition_url and coreos.live.rootfs_url parameters only support HTTP and HTTPS.

This configuration does not enable serial console access on machines with a graphical console. To configure a different console, add one or more console= arguments to the APPEND line. For example, add console=tty0 console=ttyS0 to set the first PC serial port as the primary console and the graphical console as a secondary console. For more information, see How does one set up a serial terminal and/or console in Red Hat Enterprise Linux?.

  • For iPXE:

    kernel http://<HTTP_server>/rhcos-<version>-live-kernel-<architecture> initrd=main coreos.inst.install_dev=/dev/sda coreos.inst.ignition_url=http://<HTTP_server>/worker.ign coreos.live.rootfs_url=http://<HTTP_server>/rhcos-<version>-live-rootfs.<architecture>.img 1
    initrd --name main http://<HTTP_server>/rhcos-<version>-live-initramfs.<architecture>.img 2
    1
    Specify locations of the RHCOS files that you uploaded to your HTTP server. The kernel parameter value is the location of the kernel file, the initrd=main argument is needed for booting on UEFI systems, the coreos.inst.ignition_url parameter value is the location of the worker Ignition config file, and the coreos.live.rootfs_url parameter value is the location of the live rootfs file. The coreos.inst.ignition_url and coreos.live.rootfs_url parameters only support HTTP and HTTPS.
    2
    Specify the location of the initramfs file that you uploaded to your HTTP server.

This configuration does not enable serial console access on machines with a graphical console. To configure a different console, add one or more console= arguments to the kernel line. For example, add console=tty0 console=ttyS0 to set the first PC serial port as the primary console and the graphical console as a secondary console. For more information, see How does one set up a serial terminal and/or console in Red Hat Enterprise Linux?.

  1. Use the PXE or iPXE infrastructure to create the required compute machines for your cluster.

9.3.3. Approving the certificate signing requests for your machines

When you add machines to a cluster, two pending certificate signing requests (CSRs) are generated for each machine that you added. You must confirm that these CSRs are approved or, if necessary, approve them yourself. The client requests must be approved first, followed by the server requests.

Prerequisites

  • You added machines to your cluster.

Procedure

  1. Confirm that the cluster recognizes the machines:

    $ oc get nodes

    Example output

    NAME      STATUS    ROLES   AGE  VERSION
    master-0  Ready     master  63m  v1.19.0
    master-1  Ready     master  63m  v1.19.0
    master-2  Ready     master  64m  v1.19.0
    worker-0  NotReady  worker  76s  v1.19.0
    worker-1  NotReady  worker  70s  v1.19.0

    The output lists all of the machines that you created.

    Note

    The preceding output might not include the compute nodes, also known as worker nodes, until some CSRs are approved.

  2. Review the pending CSRs and ensure that you see the client requests with the Pending or Approved status for each machine that you added to the cluster:

    $ oc get csr

    Example output

    NAME        AGE     REQUESTOR                                                                   CONDITION
    csr-8b2br   15m     system:serviceaccount:openshift-machine-config-operator:node-bootstrapper   Pending
    csr-8vnps   15m     system:serviceaccount:openshift-machine-config-operator:node-bootstrapper   Pending
    ...

    In this example, two machines are joining the cluster. You might see more approved CSRs in the list.

  3. If the CSRs were not approved, after all of the pending CSRs for the machines you added are in Pending status, approve the CSRs for your cluster machines:

    Note

    Because the CSRs rotate automatically, approve your CSRs within an hour of adding the machines to the cluster. If you do not approve them within an hour, the certificates will rotate, and more than two certificates will be present for each node. You must approve all of these certificates. Once the client CSR is approved, the Kubelet creates a secondary CSR for the serving certificate, which requires manual approval. Then, subsequent serving certificate renewal requests are automatically approved by the machine-approver if the Kubelet requests a new certificate with identical parameters.

    Note

    For clusters running on platforms that are not machine API enabled, such as bare metal and other user-provisioned infrastructure, you must implement a method of automatically approving the kubelet serving certificate requests (CSRs). If a request is not approved, then the oc exec, oc rsh, and oc logs commands cannot succeed, because a serving certificate is required when the API server connects to the kubelet. Any operation that contacts the Kubelet endpoint requires this certificate approval to be in place. The method must watch for new CSRs, confirm that the CSR was submitted by the node-bootstrapper service account in the system:node or system:admin groups, and confirm the identity of the node.

    • To approve them individually, run the following command for each valid CSR:

      $ oc adm certificate approve <csr_name> 1
      1
      <csr_name> is the name of a CSR from the list of current CSRs.
    • To approve all pending CSRs, run the following command:

      $ oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs --no-run-if-empty oc adm certificate approve
      Note

      Some Operators might not become available until some CSRs are approved.

  4. Now that your client requests are approved, you must review the server requests for each machine that you added to the cluster:

    $ oc get csr

    Example output

    NAME        AGE     REQUESTOR                                                                   CONDITION
    csr-bfd72   5m26s   system:node:ip-10-0-50-126.us-east-2.compute.internal                       Pending
    csr-c57lv   5m26s   system:node:ip-10-0-95-157.us-east-2.compute.internal                       Pending
    ...

  5. If the remaining CSRs are not approved, and are in the Pending status, approve the CSRs for your cluster machines:

    • To approve them individually, run the following command for each valid CSR:

      $ oc adm certificate approve <csr_name> 1
      1
      <csr_name> is the name of a CSR from the list of current CSRs.
    • To approve all pending CSRs, run the following command:

      $ oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs oc adm certificate approve
  6. After all client and server CSRs have been approved, the machines have the Ready status. Verify this by running the following command:

    $ oc get nodes

    Example output

    NAME      STATUS    ROLES   AGE  VERSION
    master-0  Ready     master  73m  v1.20.0
    master-1  Ready     master  73m  v1.20.0
    master-2  Ready     master  74m  v1.20.0
    worker-0  Ready     worker  11m  v1.20.0
    worker-1  Ready     worker  11m  v1.20.0

    Note

    It can take a few minutes after approval of the server CSRs for the machines to transition to the Ready status.

Additional information

Chapter 10. Deploying machine health checks

You can configure and deploy a machine health check to automatically repair damaged machines in a machine pool.

Important

This process is not applicable for clusters with manually provisioned machines. You can use the advanced machine management and scaling capabilities only in clusters where the Machine API is operational.

10.1. About machine health checks

You can define conditions under which machines in a cluster are considered unhealthy by using a MachineHealthCheck resource. Machines matching the conditions are automatically remediated.

To monitor machine health, create a MachineHealthCheck custom resource (CR) that includes a label for the set of machines to monitor and a condition to check, such as staying in the NotReady status for 15 minutes or displaying a permanent condition in the node-problem-detector.

The controller that observes a MachineHealthCheck CR checks for the condition that you defined. If a machine fails the health check, the machine is automatically deleted and a new one is created to take its place. When a machine is deleted, you see a machine deleted event.

Note

For machines with the master role, the machine health check reports the number of unhealthy nodes, but the machine is not deleted. For example:

Example output

$ oc get machinehealthcheck example -n openshift-machine-api

NAME      MAXUNHEALTHY   EXPECTEDMACHINES   CURRENTHEALTHY
example   40%            3                  1

To limit the disruptive impact of machine deletions, the controller drains and deletes only one node at a time. If there are more unhealthy machines than the maxUnhealthy threshold allows for in the targeted pool of machines, the controller stops deleting machines and you must manually intervene.

To stop the check, remove the custom resource.

10.1.1. MachineHealthChecks on Bare Metal

Machine deletion on bare metal cluster triggers reprovisioning of a bare metal host. Usually bare metal reprovisioning is a lengthy process, during which the cluster is missing compute resources and applications might be interrupted. To change the default remediation process from machine deletion to host power-cycle, annotate the MachineHealthCheck resource with the machine.openshift.io/remediation-strategy: external-baremetal annotation.

After you set the annotation, unhealthy machines are power-cycled by using BMC credentials.

10.1.2. Limitations when deploying machine health checks

There are limitations to consider before deploying a machine health check:

  • Only machines owned by a machine set are remediated by a machine health check.
  • Control plane machines are not currently supported and are not remediated if they are unhealthy.
  • If the node for a machine is removed from the cluster, a machine health check considers the machine to be unhealthy and remediates it immediately.
  • If the corresponding node for a machine does not join the cluster after the nodeStartupTimeout, the machine is remediated.
  • A machine is remediated immediately if the Machine resource phase is Failed.

Additional resources

10.2. Sample MachineHealthCheck resource

The MachineHealthCheck resource resembles one of the following YAML files:

MachineHealthCheck for bare metal

apiVersion: machine.openshift.io/v1beta1
kind: MachineHealthCheck
metadata:
  name: example 1
  namespace: openshift-machine-api
  annotations:
    machine.openshift.io/remediation-strategy: external-baremetal 2
spec:
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-machine-role: <role> 3
      machine.openshift.io/cluster-api-machine-type: <role> 4
      machine.openshift.io/cluster-api-machineset: <cluster_name>-<label>-<zone> 5
  unhealthyConditions:
  - type:    "Ready"
    timeout: "300s" 6
    status: "False"
  - type:    "Ready"
    timeout: "300s" 7
    status: "Unknown"
  maxUnhealthy: "40%" 8
  nodeStartupTimeout: "10m" 9

1
Specify the name of the machine health check to deploy.
2
For bare metal clusters, you must include the machine.openshift.io/remediation-strategy: external-baremetal annotation in the annotations section to enable power-cycle remediation. With this remediation strategy, unhealthy hosts are rebooted instead of removed from the cluster.
3 4
Specify a label for the machine pool that you want to check.
5
Specify the machine set to track in <cluster_name>-<label>-<zone> format. For example, prod-node-us-east-1a.
6 7
Specify the timeout duration for a node condition. If a condition is met for the duration of the timeout, the machine will be remediated. Long timeouts can result in long periods of downtime for a workload on an unhealthy machine.
8
Specify the amount of machines allowed to be concurrently remediated in the targeted pool. This can be set as a percentage or an integer. If the number of unhealthy machines exceeds the limit set by maxUnhealthy, remediation is not performed.
9
Specify the timeout duration that a machine health check must wait for a node to join the cluster before a machine is determined to be unhealthy.
Note

The matchLabels are examples only; you must map your machine groups based on your specific needs.

MachineHealthCheck for all other installation types

apiVersion: machine.openshift.io/v1beta1
kind: MachineHealthCheck
metadata:
  name: example 1
  namespace: openshift-machine-api
spec:
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-machine-role: <role> 2
      machine.openshift.io/cluster-api-machine-type: <role> 3
      machine.openshift.io/cluster-api-machineset: <cluster_name>-<label>-<zone> 4
  unhealthyConditions:
  - type:    "Ready"
    timeout: "300s" 5
    status: "False"
  - type:    "Ready"
    timeout: "300s" 6
    status: "Unknown"
  maxUnhealthy: "40%" 7
  nodeStartupTimeout: "10m" 8

1
Specify the name of the machine health check to deploy.
2 3
Specify a label for the machine pool that you want to check.
4
Specify the machine set to track in <cluster_name>-<label>-<zone> format. For example, prod-node-us-east-1a.
5 6
Specify the timeout duration for a node condition. If a condition is met for the duration of the timeout, the machine will be remediated. Long timeouts can result in long periods of downtime for a workload on an unhealthy machine.
7
Specify the amount of machines allowed to be concurrently remediated in the targeted pool. This can be set as a percentage or an integer. If the number of unhealthy machines exceeds the limit set by maxUnhealthy, remediation is not performed.
8
Specify the timeout duration that a machine health check must wait for a node to join the cluster before a machine is determined to be unhealthy.
Note

The matchLabels are examples only; you must map your machine groups based on your specific needs.

10.2.1. Short-circuiting machine health check remediation

Short circuiting ensures that machine health checks remediate machines only when the cluster is healthy. Short-circuiting is configured through the maxUnhealthy field in the MachineHealthCheck resource.

If the user defines a value for the maxUnhealthy field, before remediating any machines, the MachineHealthCheck compares the value of maxUnhealthy with the number of machines within its target pool that it has determined to be unhealthy. Remediation is not performed if the number of unhealthy machines exceeds the maxUnhealthy limit.

Important

If maxUnhealthy is not set, the value defaults to 100% and the machines are remediated regardless of the state of the cluster.

The appropriate maxUnhealthy value depends on the scale of the cluster you deploy and how many machines the MachineHealthCheck covers. For example, you can use the maxUnhealthy value to cover multiple machine sets across multiple availability zones so that if you lose an entire zone, your maxUnhealthy setting prevents further remediation within the cluster.

The maxUnhealthy field can be set as either an integer or percentage. There are different remediation implementations depending on the maxUnhealthy value.

10.2.1.1. Setting maxUnhealthy by using an absolute value

If maxUnhealthy is set to 2:

  • Remediation will be performed if 2 or fewer nodes are unhealthy
  • Remediation will not be performed if 3 or more nodes are unhealthy

These values are independent of how many machines are being checked by the machine health check.

10.2.1.2. Setting maxUnhealthy by using percentages

If maxUnhealthy is set to 40% and there are 25 machines being checked:

  • Remediation will be performed if 10 or fewer nodes are unhealthy
  • Remediation will not be performed if 11 or more nodes are unhealthy

If maxUnhealthy is set to 40% and there are 6 machines being checked:

  • Remediation will be performed if 2 or fewer nodes are unhealthy
  • Remediation will not be performed if 3 or more nodes are unhealthy
Note

The allowed number of machines is rounded down when the percentage of maxUnhealthy machines that are checked is not a whole number.

10.3. Creating a MachineHealthCheck resource

Additional resources

You can create a MachineHealthCheck resource for all MachineSets in your cluster. You should not create a MachineHealthCheck resource that targets control plane machines.

Prerequisites

  • Install the oc command line interface.

Procedure

  1. Create a healthcheck.yml file that contains the definition of your machine health check.
  2. Apply the healthcheck.yml file to your cluster:

    $ oc apply -f healthcheck.yml

Legal Notice

Copyright © 2021 Red Hat, Inc.
The text of and illustrations in this document are licensed by Red Hat under a Creative Commons Attribution–Share Alike 3.0 Unported license ("CC-BY-SA"). An explanation of CC-BY-SA is available at http://creativecommons.org/licenses/by-sa/3.0/. In accordance with CC-BY-SA, if you distribute this document or an adaptation of it, you must provide the URL for the original version.
Red Hat, as the licensor of this document, waives the right to enforce, and agrees not to assert, Section 4d of CC-BY-SA to the fullest extent permitted by applicable law.
Red Hat, Red Hat Enterprise Linux, the Shadowman logo, the Red Hat logo, JBoss, OpenShift, Fedora, the Infinity logo, and RHCE are trademarks of Red Hat, Inc., registered in the United States and other countries.
Linux® is the registered trademark of Linus Torvalds in the United States and other countries.
Java® is a registered trademark of Oracle and/or its affiliates.
XFS® is a trademark of Silicon Graphics International Corp. or its subsidiaries in the United States and/or other countries.
MySQL® is a registered trademark of MySQL AB in the United States, the European Union and other countries.
Node.js® is an official trademark of Joyent. Red Hat is not formally related to or endorsed by the official Joyent Node.js open source or commercial project.
The OpenStack® Word Mark and OpenStack logo are either registered trademarks/service marks or trademarks/service marks of the OpenStack Foundation, in the United States and other countries and are used with the OpenStack Foundation's permission. We are not affiliated with, endorsed or sponsored by the OpenStack Foundation, or the OpenStack community.
All other trademarks are the property of their respective owners.