You can update, or upgrade, an OpenShift Container Platform cluster between minor versions.

Because of the difficulty of changing update channels by using oc, use the web console to change the update channel. It is recommended to complete the update process within the web console. You can follow the steps in Updating a cluster within a minor version by using the CLI to complete the update after you change to a 4.2 channel.

Prerequisites

About the OpenShift Container Platform update service

The OpenShift Container Platform update service is the hosted service that provides over-the-air updates to both OpenShift Container Platform and Red Hat Enterprise Linux CoreOS (RHCOS). It provides a graph, or diagram that contain vertices and the edges that connect them, of component Operators. The edges in the graph show which versions you can safely update to, and the vertices are update payloads that specify the intended state of the managed cluster components.

The Cluster Version Operator (CVO) in your cluster checks with the OpenShift Container Platform update service to see the valid updates and update paths based on current component versions and information in the graph. When you request an update, the OpenShift Container Platform CVO uses the release image for that update to upgrade your cluster. The release artifacts are hosted in Quay as container images.

To allow the OpenShift Container Platform update service to provide only compatible updates, a release verification pipeline exists to drive automation. Each release artifact is verified for compatibility with supported cloud platforms and system architectures as well as other component packages. After the pipeline confirms the suitability of a release, the OpenShift Container Platform update service notifies you that it is available.

Because the update service displays all valid updates, you must not force an update to a version that the update service does not display.

During continuous update mode, two controllers run. One continuously updates the payload manifests, applies them to the cluster, and outputs the status of the controlled rollout of the Operators, whether they are available, upgrading, or failed. The second controller polls the OpenShift Container Platform update service to determine if updates are available.

Reverting your cluster to a previous version, or a rollback, is not supported. Only upgrading to a newer version is supported.

Understanding OpenShift Container Platform upgrade channels

In OpenShift Container Platform 4.1, Red Hat introduced the concept of upgrade channels for recommending the appropriate upgrade versions to your cluster. Upgrade channels separate upgrade strategies and also are used to control the cadence of updates. Channels are tied to a minor version of OpenShift Container Platform. For instance, OpenShift Container Platform 4.2 channels will never include an upgrade to a 4.3 release. This ensures administrators make an explicit decision to upgrade to the next minor version of OpenShift Container Platform. Channels only control updates and have no impact on the version of the cluster you install; the openshift-install binary for a given patch level of OpenShift Container Platform always installs that patch level.

See OpenShift 4.2 Upgrades phased roll out for more information on the types of updates and upgrade channels.

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.

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

  2. For production clusters, ensure that the CHANNEL is set to the correct channel for your current minor version, such as stable-4.2.

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

    • If the UPDATE STATUS is not Updates Available, you cannot upgrade your cluster.

    • The DESIRED VERSION indicates the cluster version that your cluster is running or is updating to.

  3. Click Updates Available, select the highest available version and click Update. The UPDATE STATUS changes to Updating, and you can review the progress of the Operator upgrades on the Cluster Operators tab.

  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-* 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.