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Chapter 7. Updating a cluster using the web console

You can update, or upgrade, an OpenShift Container Platform cluster by using the web console. The following steps update a cluster within a minor version. You can use the same instructions for updating a cluster between minor versions.

Note

Use the web console or oc adm upgrade channel <channel> to change the update channel. You can follow the steps in Updating a cluster using the CLI to complete the update after you change to a 4.11 channel.

7.1. Prerequisites

  • Have access to the cluster as a user with admin privileges. See Using RBAC to define and apply permissions.
  • Have a recent etcd backup in case your update fails and you must restore your cluster to a previous state.
  • Support for RHEL7 workers is removed in OpenShift Container Platform 4.11. You must replace RHEL7 workers with RHEL8 or RHCOS workers before upgrading to OpenShift Container Platform 4.11. Red Hat does not support in-place RHEL7 to RHEL8 updates for RHEL workers; those hosts must be replaced with a clean operating system install.
  • Ensure all Operators previously installed through Operator Lifecycle Manager (OLM) are updated to their latest version in their latest channel. Updating the Operators ensures they have a valid update path when the default OperatorHub catalogs switch from the current minor version to the next during a cluster update. See Updating installed Operators for more information.
  • Ensure that all machine config pools (MCPs) are running and not paused. Nodes associated with a paused MCP are skipped during the update process. You can pause the MCPs if you are performing a canary rollout update strategy.
  • To accommodate the time it takes to update, you are able to do a partial update by updating the worker or custom pool nodes. You can pause and resume within the progress bar of each pool.
  • If your cluster uses manually maintained credentials, update the cloud provider resources for the new release. For more information, including how to determine if this is a requirement for your cluster, see Preparing to update a cluster with manually maintained credentials.
  • If you run an Operator or you have configured any application with the pod disruption budget, you might experience an interruption during the upgrade process. If minAvailable is set to 1 in PodDisruptionBudget, the nodes are drained to apply pending machine configs which might block the eviction process. If several nodes are rebooted, all the pods might run on only one node, and the PodDisruptionBudget field can prevent the node drain.
Important
  • When an update is failing to complete, the Cluster Version Operator (CVO) reports the status of any blocking components while attempting to reconcile the update. Rolling your cluster back to a previous version is not supported. If your update is failing to complete, contact Red Hat support.
  • Using the unsupportedConfigOverrides section to modify the configuration of an Operator is unsupported and might block cluster updates. You must remove this setting before you can update your cluster.

Additional resources

7.2. Performing a canary rollout update

In some specific use cases, you might want a more controlled update process where you do not want specific nodes updated concurrently with the rest of the cluster. These use cases include, but are not limited to:

  • You have mission-critical applications that you do not want unavailable during the update. You can slowly test the applications on your nodes in small batches after the update.
  • You have a small maintenance window that does not allow the time for all nodes to be updated, or you have multiple maintenance windows.

The rolling update process is not a typical update workflow. With larger clusters, it can be a time-consuming process that requires you execute multiple commands. This complexity can result in errors that can affect the entire cluster. It is recommended that you carefully consider whether your organization wants to use a rolling update and carefully plan the implementation of the process before you start.

The rolling update process described in this topic involves:

  • Creating one or more custom machine config pools (MCPs).
  • Labeling each node that you do not want to update immediately to move those nodes to the custom MCPs.
  • Pausing those custom MCPs, which prevents updates to those nodes.
  • Performing the cluster update.
  • Unpausing one custom MCP, which triggers the update on those nodes.
  • Testing the applications on those nodes to make sure the applications work as expected on those newly-updated nodes.
  • Optionally removing the custom labels from the remaining nodes in small batches and testing the applications on those nodes.
Note

Pausing an MCP prevents the Machine Config Operator from applying any configuration changes on the associated nodes. Pausing an MCP also prevents any automatically rotated certificates from being pushed to the associated nodes, including the automatic CA rotation of the kube-apiserver-to-kubelet-signer CA certificate.

If the MCP is paused when the kube-apiserver-to-kubelet-signer CA certificate expires and the MCO attempts to automatically renew the certificate, the new certificate is created but not applied across the nodes in the respective machine config pool. This causes failure in multiple oc commands, including oc debug, oc logs, oc exec, and oc attach. You receive alerts in the Alerting UI of the OpenShift Container Platform web console if an MCP is paused when the certificates are rotated.

Pausing an MCP should be done with careful consideration about the kube-apiserver-to-kubelet-signer CA certificate expiration and for short periods of time only.

If you want to use the canary rollout update process, see Performing a canary rollout update.

7.3. Pausing a MachineHealthCheck resource by using the web console

During the upgrade process, nodes in the cluster might become temporarily unavailable. In the case of worker nodes, the machine health check might identify such nodes as unhealthy and reboot them. To avoid rebooting such nodes, pause all the MachineHealthCheck resources before updating the cluster.

Prerequisites

  • You have access to the cluster with cluster-admin privileges.
  • You have access to the OpenShift Container Platform web console.

Procedure

  1. Log in to the OpenShift Container Platform web console.
  2. Navigate to Compute MachineHealthChecks.

  3. To pause the machine health checks, add the cluster.x-k8s.io/paused="" annotation to each MachineHealthCheck resource. For example, to add the annotation to the machine-api-termination-handler resource, complete the following steps:

    1. Click the Options menu kebab next to the machine-api-termination-handler and click Edit annotations.
    2. In the Edit annotations dialog, click Add more.
    3. In the Key and Value fields, add cluster.x-k8s.io/paused and "" values, respectively, and click Save.

7.4. About updating single node OpenShift Container Platform

You can update, or upgrade, a single-node OpenShift Container Platform cluster by using either the console or CLI.

However, note the following limitations:

  • The prerequisite to pause the MachineHealthCheck resources is not required because there is no other node to perform the health check.
  • Restoring a single-node OpenShift Container Platform cluster using an etcd backup is not officially supported. However, it is good practice to perform the etcd backup in case your upgrade fails. If your control plane is healthy, you might be able to restore your cluster to a previous state by using the backup.

  • Updating a single-node OpenShift Container Platform cluster requires downtime and can include an automatic reboot. The amount of downtime depends on the update payload, as described in the following scenarios:

    • If the update payload contains an operating system update, which requires a reboot, the downtime is significant and impacts cluster management and user workloads.
    • If the update contains machine configuration changes that do not require a reboot, the downtime is less, and the impact on the cluster management and user workloads is lessened. In this case, the node draining step is skipped with single-node OpenShift Container Platform because there is no other node in the cluster to reschedule the workloads to.
    • If the update payload does not contain an operating system update or machine configuration changes, a short API outage occurs and resolves quickly.
Important

There are conditions, such as bugs in an updated package, that can cause the single node to not restart after a reboot. In this case, the update does not rollback automatically.

Additional resources

7.5. Updating a cluster by using the web console

If updates are available, you can update your cluster from the web console.

You can find information about available OpenShift Container Platform advisories and updates in the errata section of the Customer Portal.

Prerequisites

  • Have access to the web console as a user with admin privileges.
  • Pause all MachineHealthCheck resources.

Procedure

  1. From the web console, click Administration Cluster Settings and review the contents of the Details tab.

  2. For production clusters, ensure that the Channel is set to the correct channel for the version that you want to update to, such as stable-4.11.

    Important

    For production clusters, you must subscribe to a stable-*, eus-* or fast-* channel.

    Note

    When you are ready to move to the next minor version, choose the channel that corresponds to that minor version. The sooner the update channel is declared, the more effectively the cluster can recommend update paths to your target version. The cluster might take some time to evaluate all the possible updates that are available and offer the best update recommendations to choose from. Update recommendations can change over time, as they are based on what update options are available at the time.

    If you cannot see an update path to your target minor version, keep updating your cluster to the latest patch release for your current version until the next minor version is available in the path.

    • If the Update status is not Updates available, you cannot update your cluster.
    • Select channel indicates the cluster version that your cluster is running or is updating to.

  3. Select a version to update to, and click Save.

    The Input channel Update status changes to Update to <product-version> in progress, and you can review the progress of the cluster update by watching the progress bars for the Operators and nodes.

    Note

    If you are upgrading your cluster to the next minor version, like version 4.y to 4.(y+1), it is recommended to confirm your nodes are updated before deploying workloads that rely on a new feature. Any pools with worker nodes that are not yet updated are displayed on the Cluster Settings page.

  4. After the update completes and the Cluster Version Operator refreshes the available updates, check if more updates are available in your current channel.

    • If updates are available, continue to perform updates in the current channel until you can no longer update.
    • If no updates are available, change the Channel to the stable-*, eus-* or fast-* channel for the next minor version, and update to the version that you want in that channel.

    You might need to perform several intermediate updates until you reach the version that you want.

7.6. Changing the update server by using the web console

Changing the update server is optional. If you have an OpenShift Update Service (OSUS) installed and configured locally, you must set the URL for the server as the upstream to use the local server during updates.

Procedure

  1. Navigate to Administration Cluster Settings, click version.

  2. Click the YAML tab and then edit the upstream parameter value:

    Example output

      ...
  spec:
    clusterID: db93436d-7b05-42cc-b856-43e11ad2d31a
    upstream: '<update-server-url>' 1
  ...

    1
    The <update-server-url> variable specifies the URL for the update server.

    The default upstream is https://api.openshift.com/api/upgrades_info/v1/graph.

  3. Click Save.

Additional resources

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