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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.

You can use the advanced machine management and scaling capabilities only in clusters where the Machine API is operational. Clusters with user-provisioned infrastructure require additional validation and configuration to use the Machine API.

Clusters with the infrastructure platform type none cannot use the Machine API. This limitation applies even if the compute machines that are attached to the cluster are installed on a platform that supports the feature. This parameter cannot be changed after installation.

To view the platform type for your cluster, run the following command:

$ oc get infrastructure cluster -o jsonpath='{.status.platform}'

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> (1)
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role>-<zone> (2)
  template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id> (1)
        machine.openshift.io/cluster-api-machine-role: <role> (3)
        machine.openshift.io/cluster-api-machine-type: <role> (3)
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role>-<zone> (2)
    spec:
      metadata:
        labels:
          node-role.kubernetes.io/<role>: "" (3)
      providerSpec:
        value:
          ami:
            id: ami-046fe691f52a953f9 (4)
          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 (1)
          instanceType: m4.large
          kind: AWSMachineProviderConfig
          placement:
            availabilityZone: <zone> (5)
            region: <region> (6)
          securityGroups:
            - filters:
                - name: tag:Name
                  values:
                    - <infrastructure_id>-worker-sg (1)
          subnet:
            filters:
              - name: tag:Name
                values:
                  - <infrastructure_id>-private-<zone> (7)
          tags:
            - name: kubernetes.io/cluster/<infrastructure_id> (1)
              value: owned
          userDataSecret:
            name: worker-user-data
1 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 Specify the infrastructure ID, node label, and zone.
3 Specify the node label to add.
4 Specify a valid Red Hat Enterprise Linux CoreOS (RHCOS) AMI for your AWS zone for your OpenShift Container Platform nodes. If you want to use an AWS Marketplace image, you must complete the OpenShift Container Platform subscription from the AWS Marketplace to obtain an AMI ID for your region.
5 Specify the zone, for example, us-east-1a.
6 Specify the region, for example, us-east-1.
7 Specify the infrastructure ID and zone.

Creating a machine set

In addition to the compute machine sets created by the installation program, you can create your own 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.

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

    1. To list the compute machine sets in your cluster, run the following command:

      $ 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. To view values of a specific compute machine set custom resource (CR), run the following command:

      $ oc get machineset <machineset_name> \
  -n openshift-machine-api -o yaml
      Example output
      apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  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>
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role>
  template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id>
        machine.openshift.io/cluster-api-machine-role: <role>
        machine.openshift.io/cluster-api-machine-type: <role>
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role>
    spec:
      providerSpec: (3)
        ...
      1 The cluster infrastructure ID.
      2 A default node label.

      For clusters that have user-provisioned infrastructure, a compute machine set can only create worker and infra type machines.
      3 The values in the <providerSpec> section of the compute machine set CR are platform-specific. For more information about <providerSpec> parameters in the CR, see the sample compute machine set CR configuration for your provider.

  3. Create a MachineSet CR by running the following command:

    $ oc create -f <file_name>.yaml

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

Verification

  • View the list of compute machine sets by running the following command:

    $ 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.

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.

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.

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.

    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.

Machine sets that deploy machines as Dedicated Instances

You can create a machine set running on AWS that deploys machines as Dedicated Instances. Dedicated Instances run in a virtual private cloud (VPC) on hardware that is dedicated to a single customer. These Amazon EC2 instances are physically isolated at the host hardware level. The isolation of Dedicated Instances occurs even if the instances belong to different AWS accounts that are linked to a single payer account. However, other instances that are not dedicated can share hardware with Dedicated Instances if they belong to the same AWS account.

Instances with either public or dedicated tenancy are supported by the Machine API. Instances with public tenancy run on shared hardware. Public tenancy is the default tenancy. Instances with dedicated tenancy run on single-tenant hardware.

Creating Dedicated Instances by using machine sets

You can run a machine that is backed by a Dedicated Instance by using Machine API integration. Set the tenancy field in your machine set YAML file to launch a Dedicated Instance on AWS.

Procedure

  • Specify a dedicated tenancy under the providerSpec field:

    providerSpec:
  placement:
    tenancy: dedicated