Managing hosted control planes | Hosted control planes

Configuring node tuning in a hosted cluster
Deleting a hosted cluster

After you configure your environment for hosted control planes and create a hosted cluster, you can further manage your clusters and nodes.

Configuring node tuning in a hosted cluster

Hosted control planes is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope.

To set node-level tuning on the nodes in your hosted cluster, you can use the Node Tuning Operator. In hosted control planes, you can configure node tuning by creating config maps that contain Tuned objects and referencing those config maps in your node pools.

Procedure

Create a config map that contains a valid tuned manifest, and reference the manifest in a node pool. In the following example, a Tuned manifest defines a profile that sets vm.dirty_ratio to 55 on nodes that contain the tuned-1-node-label node label with any value. Save the following ConfigMap manifest in a file named tuned-1.yaml:

    apiVersion: v1
    kind: ConfigMap
    metadata:
      name: tuned-1
      namespace: clusters
    data:
      tuning: |
        apiVersion: tuned.openshift.io/v1
        kind: Tuned
        metadata:
          name: tuned-1
          namespace: openshift-cluster-node-tuning-operator
        spec:
          profile:
          - data: |
              [main]
              summary=Custom OpenShift profile
              include=openshift-node
              [sysctl]
              vm.dirty_ratio="55"
            name: tuned-1-profile
          recommend:
          - priority: 20
            profile: tuned-1-profile

If you do not add any labels to an entry in the spec.recommend section of the Tuned spec, node-pool-based matching is assumed, so the highest priority profile in the spec.recommend section is applied to nodes in the pool. Although you can achieve more fine-grained node-label-based matching by setting a label value in the Tuned .spec.recommend.match section, node labels will not persist during an upgrade unless you set the .spec.management.upgradeType value of the node pool to InPlace.

Create the ConfigMap object in the management cluster:

$ oc --kubeconfig="$MGMT_KUBECONFIG" create -f tuned-1.yaml

Reference the ConfigMap object in the spec.tuningConfig field of the node pool, either by editing a node pool or creating one. In this example, assume that you have only one NodePool, named nodepool-1, which contains 2 nodes.

    apiVersion: hypershift.openshift.io/v1alpha1
    kind: NodePool
    metadata:
      ...
      name: nodepool-1
      namespace: clusters
    ...
    spec:
      ...
      tuningConfig:
      - name: tuned-1
    status:
    ...

You can reference the same config map in multiple node pools. In hosted control planes, the Node Tuning Operator appends a hash of the node pool name and namespace to the name of the Tuned CRs to distinguish them. Outside of this case, do not create multiple TuneD profiles of the same name in different Tuned CRs for the same hosted cluster.

Verification

Now that you have created the ConfigMap object that contains a Tuned manifest and referenced it in a NodePool, the Node Tuning Operator syncs the Tuned objects into the hosted cluster. You can verify which Tuned objects are defined and which TuneD profiles are applied to each node.

List the Tuned objects in the hosted cluster:

$ oc --kubeconfig="$HC_KUBECONFIG" get Tuneds -n openshift-cluster-node-tuning-operator

Example output

NAME       AGE
default    7m36s
rendered   7m36s
tuned-1    65s

List the Profile objects in the hosted cluster:

$ oc --kubeconfig="$HC_KUBECONFIG" get Profiles -n openshift-cluster-node-tuning-operator

Example output

NAME                           TUNED            APPLIED   DEGRADED   AGE
nodepool-1-worker-1            tuned-1-profile  True      False      7m43s
nodepool-1-worker-2            tuned-1-profile  True      False      7m14s

If no custom profiles are created, the openshift-node profile is applied by default.

To confirm that the tuning was applied correctly, start a debug shell on a node and check the sysctl values:

$ oc --kubeconfig="$HC_KUBECONFIG" debug node/nodepool-1-worker-1 -- chroot /host sysctl vm.dirty_ratio

Example output

vm.dirty_ratio = 55

Deleting a hosted cluster

The steps to delete a hosted cluster differ depending on which provider you use.

Procedure

If the cluster is on AWS, follow the instructions in Destroying a hosted cluster on AWS.
If the cluster is on bare metal, follow the instructions in Destroying a hosted cluster on bare metal.

Next steps

If you want to disable the hosted control plane feature, see Disabling the hosted control plane feature.