Chapter 1. Creating a MachineSet
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 4.1 clusters, the Machine API performs all node host provisioning management actions after the cluster installation finishes. Because of this system, OpenShift Container Platform 4.1 offers an elastic, dynamic provisioning method on top of public or private cloud infrastructure.
The two primary resources are:
- A fundamental unit that describes the host for a Node. A machine has a providerSpec, 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.
- Groups of machines. MachineSets are to machines as ReplicaSets are to Pods. If you need more machines or must scale them down, you change the replicas field on the MachineSet to meet your compute need.
The following custom resources add more capabilities to your cluster:
- This resource automatically scales machines in a cloud. You can set the minimum and maximum scaling boundaries for nodes in a specified MachineSet, and the MachineAutoscaler 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.
- This resource is based on the upstream ClusterAutoscaler project. In the OpenShift Container Platform implementation, it is integrated with the Machine API by extending the MachineSet 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 ScalingPolicy so you can scale up nodes but not scale them down.
This resource detects when a machine is unhealthy, deletes it, and, on supported platforms, makes a new machine.Note
In version 4.1, MachineHealthChecks is a Technology Preview feature
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 4.1 this process is easier. Each MachineSet is scoped to a single zone, so the installation program sends out MachineSets 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. Sample YAML for a MachineSet Custom Resource
This sample YAML defines a MachineSet that runs in the
us-east-1a Amazon Web Services (AWS) region and creates nodes that are labeled with
In this sample,
<clusterID> is 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: <clusterID> 1 name: <clusterID>-<role>-us-east-1a 2 namespace: openshift-machine-api spec: replicas: 1 selector: matchLabels: machine.openshift.io/cluster-api-cluster: <clusterID> 3 machine.openshift.io/cluster-api-machineset: <clusterID>-<role>-us-east-1a 4 template: metadata: labels: machine.openshift.io/cluster-api-cluster: <clusterID> 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: <clusterID>-<role>-us-east-1a 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: <clusterID>-worker-profile 11 instanceType: m4.large kind: AWSMachineProviderConfig placement: availabilityZone: us-east-1a region: us-east-1 securityGroups: - filters: - name: tag:Name values: - <clusterID>-worker-sg 12 subnet: filters: - name: tag:Name values: - <clusterID>-private-us-east-1a 13 tags: - name: kubernetes.io/cluster/<clusterID> 14 value: owned userDataSecret: name: worker-user-data
- 1 3 5 11 12 13 14
- Specify the cluster ID that you set when you provisioned the cluster.
- 2 4 8
- Specify the cluster ID and node label.
- 6 7 9
- Specify the node label to add.
- Specify a valid Red Hat Enterprise Linux CoreOS (RHCOS) AMI for your Amazon Web Services (AWS) zone for your OpenShift Container Platform nodes.
1.3. Creating a MachineSet
In addition to the ones created by the installation program, you can create your own MachineSets to dynamically manage the machine compute resources for specific workloads of your choice.
- Deploy an OpenShift Container Platform cluster.
Install the OpenShift Command-line Interface (CLI), commonly known as
Log in to
ocas a user with
Create a new YAML file that contains the MachineSet Custom Resource sample, as shown, and is named
Ensure that you set the
If you are not sure about which value to set for an specific field, you can check an existing MachineSet from your cluster.
$ oc get machinesets -n openshift-machine-api 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
Check values of an specific MachineSet:
$ oc get machineset <machineset_name> -n \ openshift-machine-api -o yaml .... 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
Create the new
$ oc create -f <file_name>.yaml
View the list of MachineSets:
$ oc get machineset -n openshift-machine-api 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 MachineSet is available, the
CURRENTvalues match. If the MachineSet is not available, wait a few minutes and run the command again.
After the new MachineSet is available, check status of the machine and the node that it references:
$ oc describe machine <name> -n openshift-machine-api
$ oc describe machine agl030519-vplxk-infra-us-east-1a -n openshift-machine-api status: addresses: - address: 10.0.133.18 type: InternalIP - address: "" type: ExternalDNS - address: ip-10-0-133-18.ec2.internal type: InternalDNS lastUpdated: "2019-05-03T10:38:17Z" nodeRef: kind: Node name: ip-10-0-133-18.ec2.internal uid: 71fb8d75-6d8f-11e9-9ff3-0e3f103c7cd8 providerStatus: apiVersion: awsproviderconfig.openshift.io/v1beta1 conditions: - lastProbeTime: "2019-05-03T10:34:31Z" lastTransitionTime: "2019-05-03T10:34:31Z" message: machine successfully created reason: MachineCreationSucceeded status: "True" type: MachineCreation instanceId: i-09ca0701454124294 instanceState: running kind: AWSMachineProviderStatus
View the new node and confirm that the new node has the label that you specified:
$ oc get node <node_name> --show-labels
Review the command output and confirm that
node-role.kubernetes.io/<your_label>is in the
Any change to a MachineSet is not applied to existing machines owned by the MachineSet. For example, labels edited or added to an existing MachineSet are not propagated to existing machines and Nodes associated with the MachineSet.
If you need MachineSets in other availability zones, repeat this process to create more MachineSets.