Understanding update channels and releases

The fast-4.17 channel is updated with new versions of OpenShift Container Platform 4.17 as soon as Red Hat declares the version as a general availability (GA) release. As such, these releases are fully supported and purposed to be used in production environments.

While the fast-4.17 channel contains releases as soon as their errata are published, releases are added to the stable-4.17 channel after a delay. During this delay, data is collected from multiple sources and analyzed for indications of product regressions. Once a significant number of data points have been collected, these releases are added to the stable channel.

Newly installed clusters default to using stable channels.

In addition to the stable channel, all even-numbered minor versions of OpenShift Container Platform offer Extended Update Support (EUS). Releases promoted to the stable channel are also simultaneously promoted to the EUS channels. The primary purpose of the EUS channels is to serve as a convenience for clusters performing a Control Plane Only update.

The candidate-4.17 channel offers unsupported early access to releases as soon as they are built. Releases present only in candidate channels may not contain the full feature set of eventual GA releases or features may be removed prior to GA. Additionally, these releases have not been subject to full Red Hat Quality Assurance and may not offer update paths to later GA releases. Given these caveats, the candidate channel is only suitable for testing purposes where destroying and recreating a cluster is acceptable.

OpenShift Container Platform maintains an update recommendation service that knows your installed OpenShift Container Platform version and the path to take within the channel to get you to the next release. Update paths are also limited to versions relevant to your currently selected channel and its promotion characteristics.

You can imagine seeing the following releases in your channel:

The service recommends only updates that have been tested and have no known serious regressions. For example, if your cluster is on 4.17.1 and OpenShift Container Platform suggests 4.17.4, then it is recommended to update from 4.17.1 to 4.17.4.

Red Hat monitors newly released versions and update paths associated with those versions before and after they are added to supported channels.

If Red Hat removes update recommendations from any supported release, a superseding update recommendation will be provided to a future version that corrects the regression. There may however be a delay while the defect is corrected, tested, and promoted to your selected channel.

Beginning in OpenShift Container Platform 4.10, when update risks are confirmed, they are declared as Conditional Update risks for the relevant updates. Each known risk may apply to all clusters or only clusters matching certain conditions. Some examples include having the Platform set to None or the CNI provider set to OpenShiftSDN. The Cluster Version Operator (CVO) continually evaluates known risks against the current cluster state. If no risks match, the update is recommended. If the risk matches, those update paths are labeled as updates with known issues, and a reference link to the known issues is provided. The reference link helps the cluster admin decide if they want to accept the risk and continue to update their cluster.

When Red Hat chooses to declare Conditional Update risks, that action is taken in all relevant channels simultaneously. Declaration of a Conditional Update risk may happen either before or after the update has been promoted to supported channels.

Choosing the appropriate channel involves two decisions.

First, select the minor version you want for your cluster update. Selecting a channel which matches your current version ensures that you only apply z-stream updates and do not receive feature updates. Selecting an available channel which has a version greater than your current version will ensure that after one or more updates your cluster will have updated to that version. Your cluster will only be offered channels which match its current version, the next version, or the next EUS version.

Second, you should choose your desired rollout strategy. You may choose to update as soon as Red Hat declares a release GA by selecting from fast channels or you may want to wait for Red Hat to promote releases to the stable channel. Update recommendations offered in the fast-4.17 and stable-4.17 are both fully supported and benefit equally from ongoing data analysis. The promotion delay before promoting a release to the stable channel represents the only difference between the two channels. Updates to the latest z-streams are generally promoted to the stable channel within a week or two, however the delay when initially rolling out updates to the latest minor is much longer, generally 45-90 days. Please consider the promotion delay when choosing your desired channel, as waiting for promotion to the stable channel may affect your scheduling plans.

Additionally, there are several factors which may lead an organization to move clusters to the fast channel either permanently or temporarily including:

If you manage the container images for your OpenShift Container Platform clusters yourself, you must consult the Red Hat errata that is associated with product releases and note any comments that impact updates. During an update, the user interface might warn you about switching between these versions, so you must ensure that you selected an appropriate version before you bypass those warnings.

A channel can be switched from the web console or through the adm upgrade channel command:

The web console will display an alert if you switch to a channel that does not include the current release. The web console does not recommend any updates while on a channel without the current release. You can return to the original channel at any point, however.

Changing your channel might impact the supportability of your cluster. The following conditions might apply: