Creating a machine set on vSphere

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

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.

Machine API overview

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

For OKD 4.6 clusters, the Machine API performs all node host provisioning management actions after the cluster installation finishes. Because of this system, OKD 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 OKD 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 OKD version 3.11, you could not roll out a multi-zone architecture easily because the cluster did not manage machine provisioning. Beginning with OKD 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.

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.

  1. apiVersion: machine.openshift.io/v1beta1
  2. kind: MachineSet
  3. metadata:
  4.   creationTimestamp: null
  5.   labels:
  6.     machine.openshift.io/cluster-api-cluster: <infrastructure_id> (1)
  7.   name: <infrastructure_id>-<role> (2)
  8.   namespace: openshift-machine-api
  9. spec:
  10.   replicas: 1
  11.   selector:
  12.     matchLabels:
  13.       machine.openshift.io/cluster-api-cluster: <infrastructure_id> (1)
  14.       machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role> (2)
  15.   template:
  16.     metadata:
  17.       creationTimestamp: null
  18.       labels:
  19.         machine.openshift.io/cluster-api-cluster: <infrastructure_id> (1)
  20.         machine.openshift.io/cluster-api-machine-role: <role> (3)
  21.         machine.openshift.io/cluster-api-machine-type: <role> (3)
  22.         machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role> (2)
  23.     spec:
  24.       metadata:
  25.         creationTimestamp: null
  26.         labels:
  27.           node-role.kubernetes.io/<role>: "" (3)
  28.       providerSpec:
  29.         value:
  30.           apiVersion: vsphereprovider.openshift.io/v1beta1
  31.           credentialsSecret:
  32.             name: vsphere-cloud-credentials
  33.           diskGiB: 120
  34.           kind: VSphereMachineProviderSpec
  35.           memoryMiB: 8192
  36.           metadata:
  37.             creationTimestamp: null
  38.           network:
  39.             devices:
  40.             - networkName: "<vm_network_name>" (4)
  41.           numCPUs: 4
  42.           numCoresPerSocket: 1
  43.           snapshot: ""
  44.           template: <vm_template_name> (5)
  45.           userDataSecret:
  46.             name: worker-user-data
  47.           workspace:
  48.             datacenter: <vcenter_datacenter_name> (6)
  49.             datastore: <vcenter_datastore_name> (7)
  50.             folder: <vcenter_vm_folder_path> (8)
  51.             resourcepool: <vsphere_resource_pool> (9)
  52.             server: <vcenter_server_ip> (10)
1Specify 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:
  1. $ oc get -o jsonpath=’{.status.infrastructureName}{“\n”}’ infrastructure cluster
2Specify the infrastructure ID and node label.
3Specify the node label to add.
4Specify the vSphere VM network to deploy the machine set to.
5Specify the vSphere VM clone of the template to use, such as user-5ddjd-rhcos.

Do not specify the original VM template. The VM template must remain off and must be cloned for new FCOS 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.

6Specify the vCenter Datacenter to deploy the machine set on.
7Specify the vCenter Datastore to deploy the machine set on.
8Specify the path to the vSphere VM folder in vCenter, such as /dc1/vm/user-inst-5ddjd.
9Specify the vSphere resource pool for your VMs.
10Specify the vCenter server IP or fully qualified domain name.

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 OKD 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 OKD 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:

      1. $ oc get machinesets -n openshift-machine-api

      Example output

      1. NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
      2. agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
      3. agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
      4. agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
      5. agl030519-vplxk-worker-us-east-1d   0         0                             55m
      6. agl030519-vplxk-worker-us-east-1e   0         0                             55m
      7. agl030519-vplxk-worker-us-east-1f   0         0                             55m

    2. Check values of a specific machine set:

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

      Example output

      1. ...
      2. template:
      3.     metadata:
      4.       labels:
      5.         machine.openshift.io/cluster-api-cluster: agl030519-vplxk (1)
      6.         machine.openshift.io/cluster-api-machine-role: worker (2)
      7.         machine.openshift.io/cluster-api-machine-type: worker
      8.         machine.openshift.io/cluster-api-machineset: agl030519-vplxk-worker-us-east-1a
      1The cluster ID.
      2A default node label.

  2. Create the new MachineSet CR:

    1. $ oc create -f <file_name>.yaml

  3. View the list of machine sets:

    1. $ oc get machineset -n openshift-machine-api

    Example output

    1. NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
    2. agl030519-vplxk-infra-us-east-1a    1         1         1       1           11m
    3. agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
    4. agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
    5. agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
    6. agl030519-vplxk-worker-us-east-1d   0         0                             55m
    7. agl030519-vplxk-worker-us-east-1e   0         0                             55m
    8. 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.