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You can create a different machine set to serve a specific purpose in your OpenShift Container Platform cluster on Red Hat OpenStack Platform (RHOSP). 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 OpenShift Container Platform resources.

For OpenShift Container Platform 4.9 clusters, the Machine API performs all node host provisioning management actions after the cluster installation finishes. Because of this system, OpenShift Container Platform 4.9 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 OpenShift Container Platform 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 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 OpenShift Container Platform 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 RHOSP

This sample YAML defines a machine set that runs on Red Hat OpenStack Platform (RHOSP) 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)
    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>
  selector:
    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:
      providerSpec:
        value:
          apiVersion: openstackproviderconfig.openshift.io/v1alpha1
          cloudName: openstack
          cloudsSecret:
            name: openstack-cloud-credentials
            namespace: openshift-machine-api
          flavor: <nova_flavor>
          image: <glance_image_name_or_location>
          serverGroupID: <optional_UUID_of_server_group> (4)
          kind: OpenstackProviderSpec
          networks: (5)
          - filter: {}
            subnets:
            - filter:
                name: <subnet_name>
                tags: openshiftClusterID=<infrastructure_id> (1)
          primarySubnet: <rhosp_subnet_UUID> (6)
          securityGroups:
          - filter: {}
            name: <infrastructure_id>-worker (1)
          serverMetadata:
            Name: <infrastructure_id>-worker (1)
            openshiftClusterID: <infrastructure_id> (1)
          tags:
          - openshiftClusterID=<infrastructure_id> (1)
          trunk: true
          userDataSecret:
            name: worker-user-data (2)
          availabilityZone: <optional_openstack_availability_zone>
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 node label to add.
3 Specify the infrastructure ID and node label.
4 To set a server group policy for the MachineSet, enter the value that is returned from creating a server group. For most deployments, anti-affinity or soft-anti-affinity policies are recommended.
5 Required for deployments to multiple networks. To specify multiple networks, add another entry in the networks array. Also, you must include the network that is used as the primarySubnet value.
6 Specify the RHOSP subnet that you want the endpoints of nodes to be published on. Usually, this is the same subnet that is used as the value of machinesSubnet in the install-config.yaml file.

Sample YAML for a machine set custom resource that uses SR-IOV on RHOSP

If you configured your cluster for single-root I/O virtualization (SR-IOV), you can create machine sets that use that technology.

This sample YAML defines a machine set that uses SR-IOV networks. The nodes that it creates are labeled with node-role.openshift.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 node_role is the node label to add.

The sample assumes two SR-IOV networks that are named "radio" and "uplink". The networks are used in port definitions in the spec.template.spec.providerSpec.value.ports list.

Only parameters that are specific to SR-IOV deployments are described in this sample. To review a more general sample, see "Sample YAML for a machine set custom resource on RHOSP".

An example machine set that uses SR-IOV networks
apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id>
    machine.openshift.io/cluster-api-machine-role: <node_role>
    machine.openshift.io/cluster-api-machine-type: <node_role>
  name: <infrastructure_id>-<node_role>
  namespace: openshift-machine-api
spec:
  replicas: <number_of_replicas>
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id>
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<node_role>
  template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id>
        machine.openshift.io/cluster-api-machine-role: <node_role>
        machine.openshift.io/cluster-api-machine-type: <node_role>
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<node_role>
    spec:
      metadata:
      providerSpec:
        value:
          apiVersion: openstackproviderconfig.openshift.io/v1alpha1
          cloudName: openstack
          cloudsSecret:
            name: openstack-cloud-credentials
            namespace: openshift-machine-api
          flavor: <nova_flavor>
          image: <glance_image_name_or_location>
          serverGroupID: <optional_UUID_of_server_group>
          kind: OpenstackProviderSpec
          networks:
            - subnets:
              - UUID: <machines_subnet_UUID>
          ports:
            - networkID: <radio_network_UUID> (1)
              nameSuffix: radio
              fixedIPs:
                - subnetID: <radio_subnet_UUID> (2)
              tags:
                - sriov
                - radio
              vnicType: direct (3)
              portSecurity: false (4)
            - networkID: <uplink_network_UUID> (1)
              nameSuffix: uplink
              fixedIPs:
                - subnetID: <uplink_subnet_UUID> (2)
              tags:
                - sriov
                - uplink
              vnicType: direct (3)
              portSecurity: false (4)
          primarySubnet: <machines_subnet_UUID>
          securityGroups:
          - filter: {}
            name: <infrastructure_id>-<node_role>
          serverMetadata:
            Name: <infrastructure_id>-<node_role>
            openshiftClusterID: <infrastructure_id>
          tags:
          - openshiftClusterID=<infrastructure_id>
          trunk: true
          userDataSecret:
            name: <node_role>-user-data
          availabilityZone: <optional_openstack_availability_zone>
          configDrive: true (5)
1 Enter a network UUID for each port.
2 Enter a subnet UUID for each port.
3 The value of the vnicType parameter must be direct for each port.
4 The value of the portSecurity parameter must be false for each port.

You cannot set security groups and allowed address pairs for ports when port security is disabled. Setting security groups on the instance applies the groups to all ports that are attached to it.

5 The value of the configDrive parameter must be true.

Trunking is enabled for ports that are created by entries in the networks and subnets lists. The names of ports that are created from these lists follow the pattern <machine_name>-<nameSuffix>. The nameSuffix field is required in port definitions.

You can enable trunking for each port.

Optionally, you can add tags to ports as part of their tags lists.

Sample YAML for SR-IOV deployments where port security is disabled

To create single-root I/O virtualization (SR-IOV) ports on a network that has port security disabled, define a machine set that includes the ports as items in the spec.template.spec.providerSpec.value.ports list. This difference from the standard SR-IOV machine set is due to the automatic security group and allowed address pair configuration that occurs for ports that are created by using the network and subnet interfaces.

Ports that you define for machines subnets require:

  • Allowed address pairs for the API and ingress virtual IP ports

  • The compute security group

  • Attachment to the machines network and subnet

Only parameters that are specific to SR-IOV deployments where port security is disabled are described in this sample. To review a more general sample, see Sample YAML for a machine set custom resource that uses SR-IOV on RHOSP".

An example machine set that uses SR-IOV networks and has port security disabled
apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id>
    machine.openshift.io/cluster-api-machine-role: <node_role>
    machine.openshift.io/cluster-api-machine-type: <node_role>
  name: <infrastructure_id>-<node_role>
  namespace: openshift-machine-api
spec:
  replicas: <number_of_replicas>
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id>
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<node_role>
  template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id>
        machine.openshift.io/cluster-api-machine-role: <node_role>
        machine.openshift.io/cluster-api-machine-type: <node_role>
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<node_role>
    spec:
      metadata: {}
      providerSpec:
        value:
          apiVersion: openstackproviderconfig.openshift.io/v1alpha1
          cloudName: openstack
          cloudsSecret:
            name: openstack-cloud-credentials
            namespace: openshift-machine-api
          flavor: <nova_flavor>
          image: <glance_image_name_or_location>
          kind: OpenstackProviderSpec
          ports:
            - allowedAddressPairs: (1)
              - ipAddress: <API_VIP_port_IP>
              - ipAddress: <ingress_VIP_port_IP>
              fixedIPs:
                - subnetID: <machines_subnet_UUID> (2)
              nameSuffix: nodes
              networkID: <machines_network_UUID> (2)
              securityGroups:
                  - <compute_security_group_UUID> (3)
            - networkID: <SRIOV_network_UUID>
              nameSuffix: sriov
              fixedIPs:
                - subnetID: <SRIOV_subnet_UUID>
              tags:
                - sriov
              vnicType: direct
              portSecurity: False
          primarySubnet: <machines_subnet_UUID>
          serverMetadata:
            Name: <infrastructure_ID>-<node_role>
            openshiftClusterID: <infrastructure_id>
          tags:
          - openshiftClusterID=<infrastructure_id>
          trunk: false
          userDataSecret:
            name: worker-user-data
          configDrive: True
1 Specify allowed address pairs for the API and ingress ports.
2 Specify the machines network and subnet.
3 Specify the compute machines security group.

Trunking is enabled for ports that are created by entries in the networks and subnets lists. The names of ports that are created from these lists follow the pattern <machine_name>-<nameSuffix>. The nameSuffix field is required in port definitions.

You can enable trunking for each port.

Optionally, you can add tags to ports as part of their tags lists.

If your cluster uses Kuryr and the RHOSP SR-IOV network has port security disabled, the primary port for compute machines must have:

  • The value of the spec.template.spec.providerSpec.value.networks.portSecurityEnabled parameter set to false.

  • For each subnet, the value of the spec.template.spec.providerSpec.value.networks.subnets.portSecurityEnabled parameter set to false.

  • The value of spec.template.spec.providerSpec.value.securityGroups set to empty: [].

An example section of a machine set for a cluster on Kuryr that uses SR-IOV and has port security disabled
...
          networks:
            - subnets:
              - uuid: <machines_subnet_UUID>
                portSecurityEnabled: false
              portSecurityEnabled: false
          securityGroups: []
...

In that case, you can apply the compute security group to the primary VM interface after the VM is created. For example, from a command line:

$ openstack port set --enable-port-security --security-group <infrastructure_id>-<node_role> <main_port_ID>

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 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.

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

      $ 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. Check values of a specific machine set:

      $ oc get machineset <machineset_name> -n \
           openshift-machine-api -o yaml
      Example output
      ...
      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
      1 The cluster ID.
      2 A default node label.
  2. Create the new MachineSet CR:

    $ oc create -f <file_name>.yaml
  3. View the list of machine sets:

    $ 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.