You can update, or upgrade, an OpenShift Container Platform cluster by using the web console.
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.
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.
OpenShift Container Platform 4.2, which includes the upgrade from the previous 4.1 release, has three upgrade channels to choose from:
The upgrade channels contain two types of updates:
General Availability Software (or GA) - These versions of OpenShift Container Platform are fully supported and are considered production quality. You may upgrade to the general availability release from either of the fast and stable channels.
Release Candidate Software (or RC) - These versions of OpenShift Container Platform are representative of the eventual general availability release and are available only in the candidate-4.2 channel. The release candidate will contain all the features of the product. You are allowed to upgrade from a release candidate to another release candidate and to upgrade from a previous minor version of OpenShift Container Platform to the current release candidate. Release candidate builds are not supported by Red Hat and you will not be able to upgrade from a release candidate to the general availability release of OpenShift Container Platform. Candidates should be used to test feature acceptance and assist in qualifying the next version of OpenShift Container Platform in your infrastructure.
Release candidates differ from the nightly builds found on try.openshift.com. You cannot upgrade nightly builds to nightly builds. Nightly builds are available for early access to features but are not upgradable or supported.
For GA versions, the fast and stable channels present a choice between receiving updates as soon as they are available or allowing Red Hat to control the rollout of those updates.
The fast channel is updated with new 4.2 patch versions as soon as Red Hat declares they are generally available. Use this channel if you wish to receive updates as soon as they are available or for your pre-production environments when participating in the connected customer program. This channel will contain all z-stream (4.2.z) updates but will not suggest upgrades to the next minor release (4.3.z) when the next minor release is available.
The stable channel will contain updates on a time delay as they are gradually rolled out to customers based on data from our SRE teams, support services, and pre-production and production environments that participate in our connected customer program, rather than being immediately available as they are in the fast channel. For patch and CVE fixes this can range from several hours to a day and allows an extra period of assessment in how the software performs. If issues are detected during rollout, upgrades to that version may be blocked in both the fast and stable channels, and a new version may be introduced that will be the new preferred upgrade target.
Customers can improve this process by configuring pre-production systems on the fast channel, production systems on the stable channel, and participating in Red Hat’s connected customer program - this allows Red Hat to observe the impact of updates on your specific hardware and software configurations. Future releases may improve or alter the pace at which updates move from the fast to the stable channels.
If issues are discovered with an upgrade between patch levels, Red Hat may withdraw that suggested upgrade for affected versions. A newer patch would become available in the appropriate channels and be suggested for upgrade.
OpenShift Container Platform maintains an upgrade recommendation service that understands the version of OpenShift Container Platform you have installed as well as the path to take within the channel you choose to get you to the next release. You can imagine seeing the following in the fast-4.2 channel:
The service only recommends upgrades that have been tested and have no known issues. If you are on 4.2.1 and OpenShift Container Platform is allowing you to select 4.2.4, then it is safe for you to go from .4.2.1 to .4.2.4. Likewise, the absence of 4.2.2 may be due to a CVE that was fixed in 4.2.3 and Red Hat no longer suggests upgrading to a known vulnerable version. If an issue is found that results in a new version being retracted from the recommendations, Red Hat will release a new version that is capable of upgrading from all necessary versions, including the retracted version.
Customers which have chosen to not be connected to Red Hat and are curating their own OpenShift Container Platform container image content manually should consult the Red Hat errata associated with product releases and note any comments impacting upgrades. During upgrade the user interface may caution about switching between these versions and it is up to the customer to ensure they have correctly selected the appropriate version before bypassing those cautions.
It is supported for customers to switch between the fast and stable channel at any time. Channels only offer suggested upgrades, and will never suggest a dangerous upgrade. If you switch to the candidate channel after installing from a GA version, you will see a warning the current version is not recognized, and you can safely switch back to a GA channel.
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.
Have access to the web console as a user with
From the web console, click Administration > Cluster Settings and review the contents of the Overview tab.
For production clusters, ensure that the CHANNEL is set to the correct channel for
the version that you want to update to,
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.
Click Updates Available, select
a version to update to,
and click Update.
The UPDATE STATUS changes to
Updating, and you can review the progress of
the Operator upgrades on the Cluster Operators tab.