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Managing hosted control planes

Updates for hosted control planes

Updates for hosted control planes involve updating the hosted cluster and the node pools. For a cluster to remain fully operational during an update process, you must meet the requirements of the Kubernetes version skew policy while completing the control plane and node updates.

Updates for the hosted cluster

The spec.release value dictates the version of the control plane. The HostedCluster object transmits the intended spec.release value to the HostedControlPlane.spec.release value and runs the appropriate Control Plane Operator version.

The hosted control plane manages the rollout of the new version of the control plane components along with any OpenShift Container Platform components through the new version of the Cluster Version Operator (CVO).

Updates for node pools

With node pools, you can configure the software that is running in the nodes by exposing the spec.release and spec.config values. You can start a rolling node pool update in the following ways:

  • Changing the spec.release or spec.config values.

  • Changing any platform-specific field, such as the AWS instance type. The result is a set of new instances with the new type.

  • Changing the cluster configuration, if the change propagates to the node.

Node pools support replace updates and in-place updates. The nodepool.spec.release value dictates the version of any particular node pool. A NodePool object completes a replace or an in-place rolling update according to the .spec.management.upgradeType value.

After you create a node pool, you cannot change the update type. If you want to change the update type, you must create a node pool and delete the other one.

Replace updates for node pools

A replace update creates instances in the new version while it removes old instances from the previous version. This update type is effective in cloud environments where this level of immutability is cost effective.

Replace updates do not preserve any manual changes because the node is entirely re-provisioned.

In place updates for node pools

An in-place update directly updates the operating systems of the instances. This type is suitable for environments where the infrastructure constraints are higher, such as bare metal.

In-place updates can preserve manual changes, but will report errors if you make manual changes to any file system or operating system configuration that the cluster directly manages, such as kubelet certificates.

Updating node pools for hosted control planes

On hosted control planes, you update your version of OpenShift Container Platform by updating the node pools. The node pool version must not surpass the hosted control plane version.

Procedure

  • To start the process to update to a new version of OpenShift Container Platform, change the spec.release.image value of the node pool by entering the following command:

    $ oc -n NAMESPACE patch HC HCNAME --patch '{"spec":{"release":{"image": "example"}}}' --type=merge
Verification

  • To verify that the new version was rolled out, check the .status.version value and the status conditions.

Pausing the reconciliation of a hosted cluster and hosted control plane

If you are a cluster instance administrator, you can pause the reconciliation of a hosted cluster and hosted control plane. You might want to pause reconciliation when you back up and restore an etcd database or when you need to debug problems with a hosted cluster or hosted control plane.

Procedure

  1. To pause reconciliation for a hosted cluster and hosted control plane, populate the pausedUntil field of the HostedCluster resource, as shown in the following examples. In the examples, the value for pausedUntil is defined in an environment variable prior to the command.

    • To pause the reconciliation until a specific time, specify an RFC339 timestamp:

      PAUSED_UNTIL="2022-03-03T03:28:48Z"
oc patch -n <hosted-cluster-namespace> hostedclusters/<hosted-cluster-name> -p '{"spec":{"pausedUntil":"'${PAUSED_UNTIL}'"}}' --type=merge

      The reconciliation is paused until the specified time is passed.

    • To pause the reconciliation indefinitely, pass a Boolean value of true:

      PAUSED_UNTIL="true"
oc patch -n <hosted-cluster-namespace> hostedclusters/<hosted-cluster-name> -p '{"spec":{"pausedUntil":"'${PAUSED_UNTIL}'"}}' --type=merge

      The reconciliation is paused until you remove the field from the HostedCluster resource.

      When the pause reconciliation field is populated for the HostedCluster resource, the field is automatically added to the associated HostedControlPlane resource.

  2. To remove the pausedUntil field, enter the following patch command:

    oc patch -n <hosted-cluster-namespace> hostedclusters/<hosted-cluster-name> -p '{"spec":{"pausedUntil":null}}' --type=merge

Configuring metrics sets for hosted control planes

Hosted control planes for Red Hat OpenShift Container Platform creates ServiceMonitor resources in each control plane namespace that allow a Prometheus stack to gather metrics from the control planes. The ServiceMonitor resources use metrics relabelings to define which metrics are included or excluded from a particular component, such as etcd or the Kubernetes API server. The number of metrics that are produced by control planes directly impacts the resource requirements of the monitoring stack that gathers them.

Instead of producing a fixed number of metrics that apply to all situations, you can configure a metrics set that identifies a set of metrics to produce for each control plane. The following metrics sets are supported:

  • Telemetry: These metrics are needed for telemetry. This set is the default set and is the smallest set of metrics.

  • SRE: This set includes the necessary metrics to produce alerts and allow the troubleshooting of control plane components.

  • All: This set includes all of the metrics that are produced by standalone OpenShift Container Platform control plane components.

To configure a metrics set, set the METRICS_SET environment variable in the HyperShift Operator deployment by entering the following command:

$ oc set env -n hypershift deployment/operator METRICS_SET=All

Configuring the SRE metrics set

When you specify the SRE metrics set, the HyperShift Operator looks for a config map named sre-metric-set with a single key: config. The value of the config key must contain a set of RelabelConfigs that are organized by control plane component.

You can specify the following components:

  • etcd

  • kubeAPIServer

  • kubeControllerManager

  • openshiftAPIServer

  • openshiftControllerManager

  • openshiftRouteControllerManager

  • cvo

  • olm

  • catalogOperator

  • registryOperator

  • nodeTuningOperator

  • controlPlaneOperator

  • hostedClusterConfigOperator

A configuration of the SRE metrics set is illustrated in the following example:

kubeAPIServer:
  - action:       "drop"
    regex:        "etcd_(debugging|disk|server).*"
    sourceLabels: ["__name__"]
  - action:       "drop"
    regex:        "apiserver_admission_controller_admission_latencies_seconds_.*"
    sourceLabels: ["__name__"]
  - action:       "drop"
    regex:        "apiserver_admission_step_admission_latencies_seconds_.*"
    sourceLabels: ["__name__"]
  - action:       "drop"
    regex:        "scheduler_(e2e_scheduling_latency_microseconds|scheduling_algorithm_predicate_evaluation|scheduling_algorithm_priority_evaluation|scheduling_algorithm_preemption_evaluation|scheduling_algorithm_latency_microseconds|binding_latency_microseconds|scheduling_latency_seconds)"
    sourceLabels: ["__name__"]
  - action:       "drop"
    regex:        "apiserver_(request_count|request_latencies|request_latencies_summary|dropped_requests|storage_data_key_generation_latencies_microseconds|storage_transformation_failures_total|storage_transformation_latencies_microseconds|proxy_tunnel_sync_latency_secs)"
    sourceLabels: ["__name__"]
  - action:       "drop"
    regex:        "docker_(operations|operations_latency_microseconds|operations_errors|operations_timeout)"
    sourceLabels: ["__name__"]
  - action:       "drop"
    regex:        "reflector_(items_per_list|items_per_watch|list_duration_seconds|lists_total|short_watches_total|watch_duration_seconds|watches_total)"
    sourceLabels: ["__name__"]
  - action:       "drop"
    regex:        "etcd_(helper_cache_hit_count|helper_cache_miss_count|helper_cache_entry_count|request_cache_get_latencies_summary|request_cache_add_latencies_summary|request_latencies_summary)"
    sourceLabels: ["__name__"]
  - action:       "drop"
    regex:        "transformation_(transformation_latencies_microseconds|failures_total)"
    sourceLabels: ["__name__"]
  - action:       "drop"
    regex:        "network_plugin_operations_latency_microseconds|sync_proxy_rules_latency_microseconds|rest_client_request_latency_seconds"
    sourceLabels: ["__name__"]
  - action:       "drop"
    regex:        "apiserver_request_duration_seconds_bucket;(0.15|0.25|0.3|0.35|0.4|0.45|0.6|0.7|0.8|0.9|1.25|1.5|1.75|2.5|3|3.5|4.5|6|7|8|9|15|25|30|50)"
    sourceLabels: ["__name__", "le"]
kubeControllerManager:
  - action:       "drop"
    regex:        "etcd_(debugging|disk|request|server).*"
    sourceLabels: ["__name__"]
  - action:       "drop"
    regex:        "rest_client_request_latency_seconds_(bucket|count|sum)"
    sourceLabels: ["__name__"]
  - action:       "drop"
    regex:        "root_ca_cert_publisher_sync_duration_seconds_(bucket|count|sum)"
    sourceLabels: ["__name__"]
openshiftAPIServer:
  - action:       "drop"
    regex:        "etcd_(debugging|disk|server).*"
    sourceLabels: ["__name__"]
  - action:       "drop"
    regex:        "apiserver_admission_controller_admission_latencies_seconds_.*"
    sourceLabels: ["__name__"]
  - action:       "drop"
    regex:        "apiserver_admission_step_admission_latencies_seconds_.*"
    sourceLabels: ["__name__"]
  - action:       "drop"
    regex:        "apiserver_request_duration_seconds_bucket;(0.15|0.25|0.3|0.35|0.4|0.45|0.6|0.7|0.8|0.9|1.25|1.5|1.75|2.5|3|3.5|4.5|6|7|8|9|15|25|30|50)"
    sourceLabels: ["__name__", "le"]
openshiftControllerManager:
  - action:       "drop"
    regex:        "etcd_(debugging|disk|request|server).*"
    sourceLabels: ["__name__"]
openshiftRouteControllerManager:
  - action:       "drop"
    regex:        "etcd_(debugging|disk|request|server).*"
    sourceLabels: ["__name__"]
olm:
  - action:       "drop"
    regex:        "etcd_(debugging|disk|server).*"
    sourceLabels: ["__name__"]
catalogOperator:
  - action:       "drop"
    regex:        "etcd_(debugging|disk|server).*"
    sourceLabels: ["__name__"]
cvo:
  - action: drop
    regex: "etcd_(debugging|disk|server).*"
    sourceLabels: ["__name__"]

Creating monitoring dashboards for hosted clusters

The HyperShift Operator can create or delete monitoring dashboards in the management cluster for each hosted cluster that it manages.

Enabling monitoring dashboards

To enable monitoring dashboards in a hosted cluster, complete the following steps:

Procedure

  1. Create the hypershift-operator-install-flags config map in the local-cluster namespace, being sure to specify the --monitoring-dashboards flag in the data.installFlagsToAdd section. For example:

    kind: ConfigMap
apiVersion: v1
metadata:
  name: hypershift-operator-install-flags
  namespace: local-cluster
data:
  installFlagsToAdd: "--monitoring-dashboards"
  installFlagsToRemove: ""

  2. Wait a couple of minutes for the HyperShift Operator deployment in the hypershift namespace to be updated to include the following environment variable:

        - name: MONITORING_DASHBOARDS
      value: "1"

    When monitoring dashboards are enabled, for each hosted cluster that the HyperShift Operator manages, the Operator creates a config map named cp-[NAMESPACE]-[NAME] in the openshift-config-managed namespace, where NAMESPACE is the namespace of the hosted cluster and NAME is the name of the hosted cluster. As a result, a new dashboard is added in the administrative console of the management cluster.

  3. To view the dashboard, log in to the management cluster’s console and go to the dashboard for the hosted cluster by clicking Observe → Dashboards.

  4. Optional: To disable a monitoring dashboards in a hosted cluster, remove the --monitoring-dashboards flag from the hypershift-operator-install-flags config map. When you delete a hosted cluster, its corresponding dashboard is also deleted.

Dashboard customization

To generate dashboards for each hosted cluster, the HyperShift Operator uses a template that is stored in the monitoring-dashboard-template config map in the operator namespace (hypershift). This template contains a set of Grafana panels that contain the metrics for the dashboard. You can edit the content of the config map to customize the dashboards.

When a dashboard is generated, the following strings are replaced with values that correspond to a specific hosted cluster:

Name

Description

__NAME__

The name of the hosted cluster

__NAMESPACE__

The namespace of the hosted cluster

__CONTROL_PLANE_NAMESPACE__

The namespace where the control plane pods of the hosted cluster are placed

__CLUSTER_ID__

The UUID of the hosted cluster, which matches the _id label of the hosted cluster metrics

Scaling down the data plane to zero

If you are not using the hosted control plane, to save the resources and cost you can scale down a data plane to zero.

Ensure you are prepared to scale down the data plane to zero. Because the workload from the worker nodes disappears after scaling down.
Procedure

  1. Set the kubeconfig file to access the hosted cluster by running the following command:

    $ export KUBECONFIG=<install_directory>/auth/kubeconfig

  2. Get the name of the NodePool resource associated to your hosted cluster by running the following command:

    $ oc get nodepool --namespace <HOSTED_CLUSTER_NAMESPACE>

  3. Optional: To prevent the pods from draining, add the nodeDrainTimeout field in the NodePool resource by running the following command:

    $ oc edit NodePool <nodepool> -o yaml --namespace <HOSTED_CLUSTER_NAMESPACE>
    Example output
    apiVersion: hypershift.openshift.io/v1alpha1
kind: NodePool
metadata:
# ...
  name: nodepool-1
  namespace: clusters
# ...
spec:
  arch: amd64
  clusterName: clustername (1)
  management:
    autoRepair: false
    replace:
      rollingUpdate:
        maxSurge: 1
        maxUnavailable: 0
      strategy: RollingUpdate
    upgradeType: Replace
  nodeDrainTimeout: 0s (2)
# ...
    1 Defines the name of your hosted cluster.
    2 Specifies the total amount of time that the controller spends to drain a node. By default, the nodeDrainTimeout: 0s setting blocks the node draining process.

    To allow the node draining process to continue for a certain period of time, you can set the value of the nodeDrainTimeout field accordingly, for example, nodeDrainTimeout: 1m.

  4. Scale down the NodePool resource associated to your hosted cluster by running the following command:

    $ oc scale nodepool/<NODEPOOL_NAME> --namespace <HOSTED_CLUSTER_NAMESPACE> --replicas=0

    After scaling down the data plan to zero, some pods in the control plane stay in the Pending status and the hosted control plane stays up and running. If necessary, you can scale up the NodePool resource.

  5. Optional: Scale up the NodePool resource associated to your hosted cluster by running the following command:

    $ oc scale nodepool/<NODEPOOL_NAME> --namespace <HOSTED_CLUSTER_NAMESPACE> --replicas=1

    After rescaling the NodePool resource, wait for couple of minutes for the NodePool resource to become available in a Ready state.

Deleting a hosted cluster

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

Procedure
Next steps

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