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Creating a machine set on oVirt

You can create a different machine set to serve a specific purpose in your OKD cluster on oVirt. 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 oVirt

This sample YAML defines a machine set that runs on oVirt 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> (2)
  name: <infrastructure_id>-<role> (3)
  namespace: openshift-machine-api
spec:
  replicas: <number_of_replicas> (4)
  selector: (5)
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id> (1)
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role> (3)
  template:
    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> (2)
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role> (3)
    spec:
      metadata:
        labels:
          node-role.kubernetes.io/<role>: "" (2)
      providerSpec:
        value:
          apiVersion: ovirtproviderconfig.machine.openshift.io/v1beta1
          cluster_id: <ovirt_cluster_id> (6)
          template_name: <ovirt_template_name> (7)
          instance_type_id: <instance_type_id> (8)
          cpu: (9)
            sockets: <number_of_sockets> (10)
            cores: <number_of_cores> (11)
            threads: <number_of_threads> (12)
          memory_mb: <memory_size> (13)
          guaranteed_memory_mb:  <memory_size> (14)
          os_disk: (15)
            size_gb: <disk_size> (16)
          network_interfaces: (17)
            vnic_profile_id:  <vnic_profile_id> (18)
          credentialsSecret:
            name: ovirt-credentials (19)
          kind: OvirtMachineProviderSpec
          type: <workload_type> (20)
          auto_pinning_policy: <auto_pinning_policy> (21)
          hugepages: <hugepages> (22)
          affinityGroupsNames:
            - compute (23)
          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 (oc) installed, you can obtain the infrastructure ID by running the following command: 
$ oc get -o jsonpath='{.status.infrastructureName}{"\n"}' infrastructure cluster
2 Specify the node label to add.
3 Specify the infrastructure ID and node label. These two strings together cannot be longer than 35 characters.
4 Specify the number of machines to create.
5 Selector for the machines.
6 Specify the UUID for the oVirt cluster to which this VM instance belongs.
7 Specify the oVirt VM template to use to create the machine.
8 Optional: Specify the VM instance type.

The instance_type_id field is deprecated and will be removed in a future release.

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.
9 Optional: The CPU field contains the CPU’s configuration, including sockets, cores, and threads.
10 Optional: Specify the number of sockets for a VM.
11 Optional: Specify the number of cores per socket.
12 Optional: Specify the number of threads per core.
13 Optional: Specify the size of a VM’s memory in MiB.
14 Optional: Specify the size of a virtual machine’s guaranteed memory in MiB. This is the amount of memory that is guaranteed not to be drained by the ballooning mechanism. For more information, see Memory Ballooning and Optimization Settings Explained.

If you are using a version earlier than oVirt 4.4.8, see Guaranteed memory requirements for OpenShift on Red Hat Virtualization clusters.
15 Optional: Root disk of the node.
16 Optional: Specify the size of the bootable disk in GiB.
17 Optional: List of the network interfaces of the VM. If you include this parameter, OKD discards all network interfaces from the template and creates new ones.
18 Optional: Specify the vNIC profile ID.
19 Specify the name of the secret that holds the oVirt credentials.
20 Optional: Specify the workload type for which the instance is optimized. This value affects the oVirt VM parameter. Supported values: desktop, server (default), high_performance. high_performance improves performance on the VM, but there are limitations. For example, you cannot access the VM with a graphical console. For more information, see Configuring High Performance Virtual Machines, Templates, and Pools in the Virtual Machine Management Guide.
21 Optional: AutoPinningPolicy defines the policy that automatically sets CPU and NUMA settings, including pinning to the host for this instance. Supported values: none, resize_and_pin. For more information, see Setting NUMA Nodes in the Virtual Machine Management Guide.
22 Optional: Hugepages is the size in KiB for defining hugepages in a VM. Supported values: 2048 or 1048576. For more information, see Configuring Huge Pages in the Virtual Machine Management Guide.
23 Optional: A list of affinity group names that should be applied to the VMs. The affinity groups must exist in oVirt.

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

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 OKD 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
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.