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.

  1. 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
          name: tuned-1
          namespace: clusters
          tuning: |
            apiVersion: tuned.openshift.io/v1
            kind: Tuned
              name: tuned-1
              namespace: openshift-cluster-node-tuning-operator
              - data: |
                  summary=Custom OpenShift profile
                name: tuned-1-profile
              - 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.

  2. Create the ConfigMap object in the management cluster:

    $ oc --kubeconfig="$MGMT_KUBECONFIG" create -f tuned-1.yaml
  3. 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
          name: nodepool-1
          namespace: clusters
          - name: tuned-1

    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.


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.

  1. 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
  2. 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.

  3. 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.

Next steps

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