Chapter 2. Nodes

2.1. About machine pools

Red Hat OpenShift Service on AWS uses machine pools as an elastic, dynamic provisioning method on top of your cloud infrastructure.

The primary resources are machines, compute machine sets, and machine pools.

Important

As of the Red Hat OpenShift Service on AWS versions 4.8.35, 4.9.26, 4.10.6, the Red Hat OpenShift Service on AWS default per-pod pid limit is 4096. If you want to enable this PID limit, you must upgrade your Red Hat OpenShift Service on AWS clusters to these versions or later. Red Hat OpenShift Service on AWS clusters with prior versions use a default PID limit of 1024.

You cannot configure the per-pod PID limit on any Red Hat OpenShift Service on AWS cluster.

2.1.1. Machines

A machine is a fundamental unit that describes the host for a worker node.

2.1.2. Machine sets

MachineSet resources are groups of compute machines. If you need more machines or must scale them down, change the number of replicas in the machine pool to which the compute machine sets belong.

Machine sets are not directly modifiable in ROSA.

2.1.3. Machine pools

Machine pools are a higher level construct to compute machine sets.

A machine pool creates compute machine sets that are all clones of the same configuration across availability zones. Machine pools perform all of the host node provisioning management actions on a worker node. If you need more machines or must scale them down, change the number of replicas in the machine pool to meet your compute needs. You can manually configure scaling or set autoscaling.

By default, a cluster is created with one machine pool. You can add additional machine pools to an existing cluster, modify the default machine pool, and delete machine pools.

Multiple machine pools can exist on a single cluster, and they can each have different types or different size nodes.

2.1.4. Machine pools in multiple zone clusters

When you create a machine pool in a multiple availability zone (Multi-AZ) cluster, that one machine pool has 3 zones. The machine pool, in turn, creates a total of 3 compute machine sets - one for each zone in the cluster. Each of those compute machine sets manages one or more machines in its respective availability zone.

If you create a new Multi-AZ cluster, the machine pools are replicated to those zones automatically. If you add a machine pool to an existing Multi-AZ, the new pool is automatically created in those zones. Similarly, deleting a machine pool will delete it from all zones. Due to this multiplicative effect, using machine pools in Multi-AZ cluster can consume more of your project’s quota for a specific region when creating machine pools.

2.1.5. Additional resources

2.2. Managing compute nodes

This document describes how to manage compute (also known as worker) nodes with Red Hat OpenShift Service on AWS (ROSA).

The majority of changes for compute nodes are configured on machine pools. A machine pool is a group of compute nodes in a cluster that have the same configuration, providing ease of management.

You can edit machine pool configuration options such as scaling, adding node labels, and adding taints.

2.2.1. Creating a machine pool

A default machine pool is created when you install a Red Hat OpenShift Service on AWS (ROSA) cluster. After installation, you can create additional machine pools for your cluster by using OpenShift Cluster Manager or the ROSA CLI (rosa).

2.2.1.1. Creating a machine pool using OpenShift Cluster Manager

You can create additional machine pools for your Red Hat OpenShift Service on AWS (ROSA) cluster by using OpenShift Cluster Manager.

Prerequisites

  • You created a ROSA cluster.

Procedure

  1. Navigate to OpenShift Cluster Manager Hybrid Cloud Console and select your cluster.
  2. Under the Machine pools tab, click Add machine pool.
  3. Add a Machine pool name.

  4. Select a Worker node instance type from the drop-down menu. The instance type defines the vCPU and memory allocation for each compute node in the machine pool.

    Note

    You cannot change the instance type for a machine pool after the pool is created.

  5. Optional: Configure autoscaling for the machine pool:

    1. Select Enable autoscaling to automatically scale the number of machines in your machine pool to meet the deployment needs.

    2. Set the minimum and maximum node count limits for autoscaling. The cluster autoscaler does not reduce or increase the machine pool node count beyond the limits that you specify.

      • If you deployed your cluster using a single availability zone, set the Minimum and maximum node count. This defines the minimum and maximum compute node limits in the availability zone.

      • If you deployed your cluster using multiple availability zones, set the Minimum nodes per zone and Maximum nodes per zone. This defines the minimum and maximum compute node limits per zone.

        Note

        Alternatively, you can set your autoscaling preferences for the machine pool after the machine pool is created.

  6. If you did not enable autoscaling, select a compute node count:

    • If you deployed your cluster using a single availability zone, select a Worker node count from the drop-down menu. This defines the number of compute nodes to provision to the machine pool for the zone.
    • If you deployed your cluster using multiple availability zones, select a Worker node count (per zone) from the drop-down menu. This defines the number of compute nodes to provision to the machine pool per zone.

  7. Optional: Add node labels and taints for your machine pool:

    1. Expand the Edit node labels and taints menu.
    2. Under Node labels, add Key and Value entries for your node labels.
    3. Under Taints, add Key and Value entries for your taints.

    4. For each taint, select an Effect from the drop-down menu. Available options include NoSchedule, PreferNoSchedule, and NoExecute.

      Note

      Alternatively, you can add the node labels and taints after you create the machine pool.

  8. Optional: Use Amazon EC2 Spot Instances if you want to configure your machine pool to deploy machines as non-guaranteed AWS Spot Instances:

    1. Select Use Amazon EC2 Spot Instances.

    2. Leave Use On-Demand instance price selected to use the on-demand instance price. Alternatively, select Set maximum price to define a maximum hourly price for a Spot Instance.

      For more information about Amazon EC2 Spot Instances, see the AWS documentation.

      Important

      Your Amazon EC2 Spot Instances might be interrupted at any time. Use Amazon EC2 Spot Instances only for workloads that can tolerate interruptions.

      Note

      If you select Use Amazon EC2 Spot Instances for a machine pool, you cannot disable the option after the machine pool is created.

  9. Click Add machine pool to create the machine pool.

Verification

  • Verify that the machine pool is visible on the Machine pools page and the configuration is as expected.

2.2.1.2. Creating a machine pool using the ROSA CLI

You can create additional machine pools for your Red Hat OpenShift Service on AWS (ROSA) cluster by using the ROSA CLI (rosa).

Prerequisites

  • You installed and configured the latest AWS (aws), ROSA (rosa), and OpenShift (oc) CLIs on your workstation.
  • You logged in to your Red Hat account by using the rosa CLI.
  • You created a ROSA cluster.

Procedure

  • To add a machine pool that does not use autoscaling, create the machine pool and define the instance type, compute (also known as worker) node count, and node labels: 

    $ rosa create machinepool --cluster=<cluster-name> \
                          --name=<machine_pool_id> \ 1
                          --replicas=<replica_count> \ 2
                          --instance-type=<instance_type> \ 3
                          --labels=<key>=<value>,<key>=<value> \ 4
                          --taints=<key>=<value>:<effect>,<key>=<value>:<effect> \ 5
                          --use-spot-instances \ 6
                          --spot-max-price=0.5 7
    1
    Specifies the name of the machine pool. Replace <machine_pool_id> with the name of your machine pool.
    2
    Specifies the number of compute nodes to provision. If you deployed ROSA using a single availability zone, this defines the number of compute nodes to provision to the machine pool for the zone. If you deployed your cluster using multiple availability zones, this defines the number of compute nodes to provision in total across all zones and the count must be a multiple of 3. The --replicas argument is required when autoscaling is not configured.
    3
    Optional: Sets the instance type for the compute nodes in your machine pool. The instance type defines the vCPU and memory allocation for each compute node in the pool. Replace <instance_type> with an instance type. The default is m5.xlarge. You cannot change the instance type for a machine pool after the pool is created.
    4
    Optional: Defines the labels for the machine pool. Replace <key>=<value>,<key>=<value> with a comma-delimited list of key-value pairs, for example --labels=key1=value1,key2=value2.
    5
    Optional: Defines the taints for the machine pool. Replace <key>=<value>:<effect>,<key>=<value>:<effect> with a key, value, and effect for each taint, for example --taints=key1=value1:NoSchedule,key2=value2:NoExecute. Available effects include NoSchedule, PreferNoSchedule, and NoExecute.
    6
    Optional: Configures your machine pool to deploy machines as non-guaranteed AWS Spot Instances. For information, see Amazon EC2 Spot Instances in the AWS documentation. If you select Use Amazon EC2 Spot Instances for a machine pool, you cannot disable the option after the machine pool is created.
    7
    Optional: If you have opted to use Spot Instances, you can specify this argument to define a maximum hourly price for a Spot Instance. If this argument is not specified, the on-demand price is used.
    Important

    Your Amazon EC2 Spot Instances might be interrupted at any time. Use Amazon EC2 Spot Instances only for workloads that can tolerate interruptions.

    The following example creates a machine pool called mymachinepool that uses the m5.xlarge instance type and has 2 compute node replicas. The example also adds 2 workload-specific labels: 

    $ rosa create machinepool --cluster=mycluster --name=mymachinepool --replicas=2 --instance-type=m5.xlarge --labels=app=db,tier=backend

    Example output

    I: Machine pool 'mymachinepool' created successfully on cluster 'mycluster'
I: To view all machine pools, run 'rosa list machinepools -c mycluster'

  • To add a machine pool that uses autoscaling, create the machine pool and define the autoscaling configuration, instance type and node labels: 

    $ rosa create machinepool --cluster=<cluster-name> \
                          --name=<machine_pool_id> \ 1
                          --enable-autoscaling \ 2
                          --min-replicas=<minimum_replica_count> \ 3
                          --max-replicas=<maximum_replica_count> \ 4
                          --instance-type=<instance_type> \ 5
                          --labels=<key>=<value>,<key>=<value> \ 6
                          --taints=<key>=<value>:<effect>,<key>=<value>:<effect> \ 7
                          --use-spot-instances \ 8
                          --spot-max-price=0.5 9
    1
    Specifies the name of the machine pool. Replace <machine_pool_id> with the name of your machine pool.
    2
    Enables autoscaling in the machine pool to meet the deployment needs.
    3 4
    Defines the minimum and maximum compute node limits. The cluster autoscaler does not reduce or increase the machine pool node count beyond the limits that you specify. If you deployed ROSA using a single availability zone, the --min-replicas and --max-replicas arguments define the autoscaling limits in the machine pool for the zone. If you deployed your cluster using multiple availability zones, the arguments define the autoscaling limits in total across all zones and the counts must be multiples of 3.
    5
    Optional: Sets the instance type for the compute nodes in your machine pool. The instance type defines the vCPU and memory allocation for each compute node in the pool. Replace <instance_type> with an instance type. The default is m5.xlarge. You cannot change the instance type for a machine pool after the pool is created.
    6
    Optional: Defines the labels for the machine pool. Replace <key>=<value>,<key>=<value> with a comma-delimited list of key-value pairs, for example --labels=key1=value1,key2=value2.
    7
    Optional: Defines the taints for the machine pool. Replace <key>=<value>:<effect>,<key>=<value>:<effect> with a key, value, and effect for each taint, for example --taints=key1=value1:NoSchedule,key2=value2:NoExecute. Available effects include NoSchedule, PreferNoSchedule, and NoExecute.
    8
    Optional: Configures your machine pool to deploy machines as non-guaranteed AWS Spot Instances. For information, see Amazon EC2 Spot Instances in the AWS documentation. If you select Use Amazon EC2 Spot Instances for a machine pool, you cannot disable the option after the machine pool is created.
    9
    Optional: If you have opted to use Spot Instances, you can specify this argument to define a maximum hourly price for a Spot Instance. If this argument is not specified, the on-demand price is used.
    Important

    Your Amazon EC2 Spot Instances might be interrupted at any time. Use Amazon EC2 Spot Instances only for workloads that can tolerate interruptions.

    The following example creates a machine pool called mymachinepool that uses the m5.xlarge instance type and has autoscaling enabled. The minimum compute node limit is 3 and the maximum is 6 overall. The example also adds 2 workload-specific labels: 

    $ rosa create machinepool --cluster=mycluster --name=mymachinepool --enable-autoscaling --min-replicas=3 --max-replicas=6 --instance-type=m5.xlarge --labels=app=db,tier=backend

    Example output

    I: Machine pool 'mymachinepool' created successfully on cluster 'mycluster'
I: To view all machine pools, run 'rosa list machinepools -c mycluster'

Verification

  1. List the available machine pools in your cluster: 

    $ rosa list machinepools --cluster=<cluster_name>

    Example output

    ID             AUTOSCALING  REPLICAS  INSTANCE TYPE  LABELS                  TAINTS    AVAILABILITY ZONES                    SPOT INSTANCES
Default        No           3         m5.xlarge                                        us-east-1a, us-east-1b, us-east-1c    N/A
mymachinepool  Yes          3-6       m5.xlarge      app=db, tier=backend              us-east-1a, us-east-1b, us-east-1c    No

  2. Verify that the machine pool is included in the output and the configuration is as expected.

Additional resources

2.2.2. Scaling compute nodes manually

If you have not enabled autoscaling for your machine pool, you can manually scale the number of compute (also known as worker) nodes in the pool to meet your deployment needs.

You must scale each machine pool separately.

Prerequisites

  • You installed and configured the latest AWS (aws), ROSA (rosa), and OpenShift (oc) CLIs on your workstation.
  • You logged in to your Red Hat account by using the rosa CLI.
  • You created a Red Hat OpenShift Service on AWS (ROSA) cluster.
  • You have an existing machine pool.

Procedure

  1. List the machine pools in the cluster: 

    $ rosa list machinepools --cluster=<cluster_name>

    Example output

    ID        AUTOSCALING   REPLICAS    INSTANCE TYPE  LABELS    TAINTS   AVAILABILITY ZONES
default   No            2           m5.xlarge                        us-east-1a
mp1       No            2           m5.xlarge                        us-east-1a

  2. Increase or decrease the number of compute node replicas in a machine pool: 

    $ rosa edit machinepool --cluster=<cluster_name> \
                        --replicas=<replica_count> \ 1
                        <machine_pool_id> 2
    1
    If you deployed Red Hat OpenShift Service on AWS (ROSA) using a single availability zone, the replica count defines the number of compute nodes to provision to the machine pool for the zone. If you deployed your cluster using multiple availability zones, the count defines the total number of compute nodes in the machine pool across all zones and must be a multiple of 3.
    2
    Replace <machine_pool_id> with the ID of your machine pool, as listed in the output of the preceding command.

Verification

  1. List the available machine pools in your cluster: 

    $ rosa list machinepools --cluster=<cluster_name>

    Example output

    ID        AUTOSCALING   REPLICAS    INSTANCE TYPE  LABELS    TAINTS   AVAILABILITY ZONES
default   No            2           m5.xlarge                        us-east-1a
mp1       No            3           m5.xlarge                        us-east-1a

  2. In the output of the preceding command, verify that the compute node replica count is as expected for your machine pool. In the example output, the compute node replica count for the mp1 machine pool is scaled to 3.

2.2.3. Node labels

A label is a key-value pair applied to a Node object. You can use labels to organize sets of objects and control the scheduling of pods.

You can add labels during cluster creation or after. Labels can be modified or updated at any time.

Additional resources

2.2.3.1. Adding node labels to a machine pool

Add or edit labels for compute (also known as worker) nodes at any time to manage the nodes in a manner that is relevant to you. For example, you can assign types of workloads to specific nodes.

Labels are assigned as key-value pairs. Each key must be unique to the object it is assigned to.

Prerequisites

  • You installed and configured the latest AWS (aws), ROSA (rosa), and OpenShift (oc) CLIs on your workstation.
  • You logged in to your Red Hat account by using the rosa CLI.
  • You created a Red Hat OpenShift Service on AWS (ROSA) cluster.
  • You have an existing machine pool.

Procedure

  1. List the machine pools in the cluster: 

    $ rosa list machinepools --cluster=<cluster_name>

    Example output

    ID           AUTOSCALING  REPLICAS  INSTANCE TYPE  LABELS    TAINTS    AVAILABILITY ZONES    SPOT INSTANCES
Default      No           2         m5.xlarge                          us-east-1a            N/A
db-nodes-mp  No           2         m5.xlarge                          us-east-1a            No

  2. Add or update the node labels for a machine pool:

    • To add or update node labels for a machine pool that does not use autoscaling, run the following command: 

      $ rosa edit machinepool --cluster=<cluster_name> \
                        --replicas=<replica_count> \ 1
                        --labels=<key>=<value>,<key>=<value> \ 2
                        <machine_pool_id>
      1
      For machine pools that do not use autoscaling, you must provide a replica count when adding node labels. If you do not specify the --replicas argument, you are prompted for a replica count before the command completes. If you deployed Red Hat OpenShift Service on AWS (ROSA) using a single availability zone, the replica count defines the number of compute nodes to provision to the machine pool for the zone. If you deployed your cluster using multiple availability zones, the count defines the total number of compute nodes in the machine pool across all zones and must be a multiple of 3.
      2
      Replace <key>=<value>,<key>=<value> with a comma-delimited list of key-value pairs, for example --labels=key1=value1,key2=value2. This list overwrites any modifications made to node labels on an ongoing basis.

      The following example adds labels to the db-nodes-mp machine pool: 

      $ rosa edit machinepool --cluster=mycluster --replicas=2 --labels=app=db,tier=backend db-nodes-mp

      Example output

      I: Updated machine pool 'db-nodes-mp' on cluster 'mycluster'

    • To add or update node labels for a machine pool that uses autoscaling, run the following command: 

      $ rosa edit machinepool --cluster=<cluster_name> \
                        --min-replicas=<minimum_replica_count> \ 1
                        --max-replicas=<maximum_replica_count> \ 2
                        --labels=<key>=<value>,<key>=<value> \ 3
                        <machine_pool_id>
      1 2
      For machine pools that use autoscaling, you must provide minimum and maximum compute node replica limits. If you do not specify the arguments, you are prompted for the values before the command completes. The cluster autoscaler does not reduce or increase the machine pool node count beyond the limits that you specify. If you deployed ROSA using a single availability zone, the --min-replicas and --max-replicas arguments define the autoscaling limits in the machine pool for the zone. If you deployed your cluster using multiple availability zones, the arguments define the autoscaling limits in total across all zones and the counts must be multiples of 3.
      3
      Replace <key>=<value>,<key>=<value> with a comma-delimited list of key-value pairs, for example --labels=key1=value1,key2=value2. This list overwrites any modifications made to node labels on an ongoing basis.

      The following example adds labels to the db-nodes-mp machine pool: 

      $ rosa edit machinepool --cluster=mycluster --min-replicas=2 --max-replicas=3 --labels=app=db,tier=backend db-nodes-mp

      Example output

      I: Updated machine pool 'db-nodes-mp' on cluster 'mycluster'

Verification

  1. List the available machine pools in your cluster: 

    $ rosa list machinepools --cluster=<cluster_name>

    Example output

    ID           AUTOSCALING  REPLICAS  INSTANCE TYPE  LABELS                  TAINTS    AVAILABILITY ZONES    SPOT INSTANCES
Default      No           2         m5.xlarge                                        us-east-1a            N/A
db-nodes-mp  No           2         m5.xlarge      app=db, tier=backend              us-east-1a            No

  2. Verify that the labels are included for your machine pool in the output.

2.2.4. Adding taints to a machine pool

You can add taints for compute (also known as worker) nodes in a machine pool to control which pods are scheduled to them. When you apply a taint to a machine pool, the scheduler cannot place a pod on the nodes in the pool unless the pod specification includes a toleration for the taint.

Prerequisites

  • You installed and configured the latest AWS (aws), ROSA (rosa), and OpenShift (oc) CLIs on your workstation.
  • You logged in to your Red Hat account by using the rosa CLI.
  • You created a Red Hat OpenShift Service on AWS (ROSA) cluster.
  • You have an existing machine pool.

Procedure

  1. List the machine pools in the cluster: 

    $ rosa list machinepools --cluster=<cluster_name>

    Example output

    ID           AUTOSCALING  REPLICAS  INSTANCE TYPE  LABELS    TAINTS    AVAILABILITY ZONES    SPOT INSTANCES
Default      No           2         m5.xlarge                          us-east-1a            N/A
db-nodes-mp  No           2         m5.xlarge                          us-east-1a            No

  2. Add or update the taints for a machine pool:

    • To add or update taints for a machine pool that does not use autoscaling, run the following command: 

      $ rosa edit machinepool --cluster=<cluster_name> \
                        --replicas=<replica_count> \ 1
                        --taints=<key>=<value>:<effect>,<key>=<value>:<effect> \ 2
                        <machine_pool_id>
      1
      For machine pools that do not use autoscaling, you must provide a replica count when adding taints. If you do not specify the --replicas argument, you are prompted for a replica count before the command completes. If you deployed Red Hat OpenShift Service on AWS (ROSA) using a single availability zone, the replica count defines the number of compute nodes to provision to the machine pool for the zone. If you deployed your cluster using multiple availability zones, the count defines the total number of compute nodes in the machine pool across all zones and must be a multiple of 3.
      2
      Replace <key>=<value>:<effect>,<key>=<value>:<effect> with a key, value, and effect for each taint, for example --taints=key1=value1:NoSchedule,key2=value2:NoExecute. Available effects include NoSchedule, PreferNoSchedule, and NoExecute.This list overwrites any modifications made to node taints on an ongoing basis.

      The following example adds taints to the db-nodes-mp machine pool: 

      $ rosa edit machinepool --cluster=mycluster --replicas 2 --taints=key1=value1:NoSchedule,key2=value2:NoExecute db-nodes-mp

      Example output

      I: Updated machine pool 'db-nodes-mp' on cluster 'mycluster'

    • To add or update taints for a machine pool that uses autoscaling, run the following command: 

      $ rosa edit machinepool --cluster=<cluster_name> \
                        --min-replicas=<minimum_replica_count> \ 1
                        --max-replicas=<maximum_replica_count> \ 2
                        --taints=<key>=<value>:<effect>,<key>=<value>:<effect> \ 3
                        <machine_pool_id>
      1 2
      For machine pools that use autoscaling, you must provide minimum and maximum compute node replica limits. If you do not specify the arguments, you are prompted for the values before the command completes. The cluster autoscaler does not reduce or increase the machine pool node count beyond the limits that you specify. If you deployed ROSA using a single availability zone, the --min-replicas and --max-replicas arguments define the autoscaling limits in the machine pool for the zone. If you deployed your cluster using multiple availability zones, the arguments define the autoscaling limits in total across all zones and the counts must be multiples of 3.
      3
      Replace <key>=<value>:<effect>,<key>=<value>:<effect> with a key, value, and effect for each taint, for example --taints=key1=value1:NoSchedule,key2=value2:NoExecute. Available effects include NoSchedule, PreferNoSchedule, and NoExecute.This list overwrites any modifications made to node taints on an ongoing basis.

      The following example adds taints to the db-nodes-mp machine pool: 

      $ rosa edit machinepool --cluster=mycluster --min-replicas=2 --max-replicas=3 --taints=key1=value1:NoSchedule,key2=value2:NoExecute db-nodes-mp

      Example output

      I: Updated machine pool 'db-nodes-mp' on cluster 'mycluster'

Verification

  1. List the available machine pools in your cluster: 

    $ rosa list machinepools --cluster=<cluster_name>

    Example output

    ID           AUTOSCALING  REPLICAS  INSTANCE TYPE  LABELS    TAINTS                                           AVAILABILITY ZONES    SPOT INSTANCES
Default      No           2         m5.xlarge                                                                 us-east-1a            N/A
db-nodes-mp  No           2         m5.xlarge                key1=value1:NoSchedule, key2=value2:NoExecute    us-east-1a            No

  2. Verify that the taints are included for your machine pool in the output.

2.2.5. Adding node tuning to a machine pool

You can add tunings for compute (also known as worker) nodes in a machine pool to control their configuration.

Prerequisites

  • You installed and configured the latest AWS (aws), ROSA (rosa), and OpenShift (oc) CLIs on your workstation.
  • You logged in to your Red Hat account by using the ROSA CLI.
  • You created a Red Hat OpenShift Service on AWS (ROSA) cluster.
  • You have an existing machine pool.
  • You have an existing tuning configuration.

Procedure

  1. List the machine pools in the cluster: 

    $ rosa list machinepools --cluster=<cluster_name>

    Example output

    ID           AUTOSCALING  REPLICAS  INSTANCE TYPE  LABELS    TAINTS    AVAILABILITY ZONES    SUBNET  VERSION  AUTOREPAIR  TUNING CONFIGS  MESSAGE
Default      No           2         m5.xlarge                          us-east-1a            N/A     4.12.14  Yes
db-nodes-mp  No           2         m5.xlarge                          us-east-1a            No      4.12.14  Yes

  2. You can add tuning configurations to an existing or new machine pool.

    1. Add tunings when creating a machine pool: 

      $ rosa create machinepool -c <cluster-name> <machinepoolname> --tuning-configs <tuning_config_name>

      Example output

      ? Tuning configs: sample-tuning
I: Machine pool 'db-nodes-mp' created successfully on hosted cluster 'sample-cluster'
I: To view all machine pools, run 'rosa list machinepools -c sample-cluster'

    2. Add or update the tunings for a machine pool: 

      $ rosa edit machinepool -c <cluster-name> <machinepoolname> --tuning-configs <tuningconfigname>

      Example output

      I: Updated machine pool 'db-nodes-mp' on cluster 'mycluster'

Verification

  1. List the available machine pools in your cluster: 

    $ rosa list machinepools --cluster=<cluster_name>

    Example output

    ID          AUTOSCALING  REPLICAS  INSTANCE TYPE  LABELS  TAINTS  AVAILABILITY ZONES  SUBNET  VERSION  AUTOREPAIR  TUNING CONFIGS MESSAGE
Default      No           2         m5.xlarge                     us-east-1a          N/A     4.12.14  Yes
db-nodes-mp  No           2         m5.xlarge                     us-east-1a          No      4.12.14  Yes          sample-tuning

  2. Verify that the tuning config is included for your machine pool in the output.

2.2.6. Additional resources

2.3. Configuring machine pools in Local Zones

This document describes how to configure Local Zones in machine pools with Red Hat OpenShift Service on AWS (ROSA).

2.3.1. Configuring machine pools in Local Zones

Use the following steps to configure machine pools in Local Zones.

Important

AWS Local Zones are supported on Red Hat OpenShift Service on AWS 4.12. See the Red Hat Knowledgebase article for information on how to enable Local Zones.

Prerequisites

  • ROSA is generally available in the parent region of choice. See the AWS generally available locations list to determine the Local Zone available to specific AWS regions.
  • The ROSA cluster was initially built in an existing Amazon VPC (BYO-VPC).

  • The maximum transmission unit (MTU) for the ROSA cluster is set at 1200.

    Important

    Generally, the Maximum Transmission Unit (MTU) between an Amazon EC2 instance in a Local Zone and an Amazon EC2 instance in the Region is 1300. See How Local Zones work in the AWS documentation. The cluster network MTU must always be less than the EC2 MTU to account for the overhead. The specific overhead is determined by your network plugin, for example:

    • OVN-Kubernetes: 100 bytes
    • OpenShift SDN: 50 bytes

    The network plugin could provide additional features that may also decrease the MTU. Check the documentation for additional information.

  • The AWS account has Local Zones enabled.
  • The AWS account has a Local Zone subnet for the same VPC as the cluster.
  • The AWS account has a subnet that is associated with a routing table that has a route to a NAT gateway.
  • The AWS account has the tag `kubernetes.io/cluster/<infra_id>: shared' on the associated subnet.

Procedure

  1. Create a machine pool on the cluster by running the following ROSA CLI command. 

    $ rosa create machinepool -c <cluster-name> -i

  2. Add the subnet and instance type for the machine pool in ROSA CLI. After several minutes, the cluster will provision the nodes. 

    I: Enabling interactive mode 1
? Machine pool name: xx-lz-xx 2
? Create multi-AZ machine pool: No 3
? Select subnet for a single AZ machine pool (optional): Yes 4
? Subnet ID: subnet-<a> (region-info) 5
? Enable autoscaling (optional): No 6
? Replicas: 2 7
I: Fetching instance types 8
    1
    Enables interactive mode.
    2
    Names the machine pool. This is limited to alphanumeric and a maximum length of 30 characters.
    3
    Set this option to no.
    4
    Set this option to yes.
    5
    Selects a subnet ID from the list.
    6
    Select yes to enable autoscaling or no to disable autoscaling.
    7
    Selects the number of machines for the machine pool. This number can be anywhere from 1 - 180.
    8
    Selects an instance type from the list. Only instance types that are supported in the selected Local Zone will appear.
  3. Provide the subnet ID to provision the machine pool in the Local Zone.

See the AWS Local Zones locations list on AWS for generally available and announced AWS Local Zone locations.

2.4. About autoscaling nodes on a cluster

The autoscaler option can be configured to automatically scale the number of machines in a cluster.

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.

Additionally, 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.

When you enable autoscaling, you must also set a minimum and maximum number of worker nodes.

Note

Only cluster owners and organization admins can scale or delete a cluster.

2.4.1. Enabling autoscaling nodes on a cluster

You can enable autoscaling on worker nodes to increase or decrease the number of nodes available by editing the machine pool definition for an existing cluster.

Enabling autoscaling nodes in an existing cluster using Red Hat OpenShift Cluster Manager

Enable autoscaling for worker nodes in the machine pool definition from OpenShift Cluster Manager console.

Procedure

  1. From OpenShift Cluster Manager Hybrid Cloud Console, navigate to the Clusters page and select the cluster that you want to enable autoscaling for.
  2. On the selected cluster, select the Machine pools tab.
  3. Click the Options menu kebab at the end of the machine pool that you want to enable autoscaling for and select Scale.
  4. On the Edit node count dialog, select the Enable autoscaling checkbox.
  5. Select Apply to save these changes and enable autoscaling for the cluster.
Note

Additionally, you can configure autoscaling on the default machine pool when you create the cluster using interactive mode.

Enabling autoscaling nodes in an existing cluster using the rosa CLI

Configure autoscaling to dynamically scale the number of worker nodes up or down based on load.

Successful autoscaling is dependent on having the correct AWS resource quotas in your AWS account. Verify resource quotas and request quota increases from the AWS console.

Procedure

  1. To identify the machine pool IDs in a cluster, enter the following command: 

    $ rosa list machinepools --cluster=<cluster_name>

    Example output

    ID        AUTOSCALING   REPLICAS    INSTANCE TYPE  LABELS    TINTS   AVAILABILITY ZONES
default   No            2           m5.xlarge                        us-east-1a
mp1       No            2           m5.xlarge                        us-east-1a

  2. Get the ID of the machine pools that you want to configure.

  3. To enable autoscaling on a machine pool, enter the following command: 

    $ rosa edit machinepool --cluster=<cluster_name> <machinepool_ID> --enable-autoscaling --min-replicas=<number> --max-replicas=<number>

    Example

    Enable autoscaling on a machine pool with the ID mp1 on a cluster named mycluster, with the number of replicas set to scale between 2 and 5 worker nodes: 

    $ rosa edit machinepool --cluster=mycluster mp1 --enable-autoscaling --min-replicas=2 --max-replicas=5

2.4.2. Disabling autoscaling nodes on a cluster

You can disable autoscaling on worker nodes to increase or decrease the number of nodes available by editing the machine pool definition for an existing cluster.

You can disable autoscaling on a cluster using OpenShift Cluster Manager console or the Red Hat OpenShift Service on AWS CLI.

Note

Additionally, you can configure autoscaling on the default machine pool when you create the cluster using interactive mode.

Disabling autoscaling nodes in an existing cluster using Red Hat OpenShift Cluster Manager

Disable autoscaling for worker nodes in the machine pool definition from OpenShift Cluster Manager console.

Procedure

  1. From OpenShift Cluster Manager Hybrid Cloud Console, navigate to the Clusters page and select the cluster with autoscaling that must be disabled.
  2. On the selected cluster, select the Machine pools tab.
  3. Click the Options menu kebab at the end of the machine pool with autoscaling and select Scale.
  4. On the "Edit node count" dialog, deselect the Enable autoscaling checkbox.
  5. Select Apply to save these changes and disable autoscaling from the cluster.
Disabling autoscaling nodes in an existing cluster using the rosa CLI

Disable autoscaling for worker nodes in the machine pool definition.

Procedure

  1. Enter the following command: 

    $ rosa edit machinepool --cluster=<cluster_name> <machinepool_ID> --enable-autoscaling=false --replicas=<number>

    Example

    Disable autoscaling on the default machine pool on a cluster named mycluster: 

    $ rosa edit machinepool --cluster=mycluster default --enable-autoscaling=false --replicas=3

2.4.3. Additional resources