Performing a Control Plane Only update¶

To reduce the rebooting of non-control plane hosts during cluster updates, you can perform a Control Plane Only update for your cluster.

Due to fundamental Kubernetes design, all OpenShift Container Platform updates between minor versions must be serialized. You must update from OpenShift Container Platform <4.y> to <4.y+1>, and then to <4.y+2>. You cannot update from OpenShift Container Platform <4.y> to <4.y+2> directly. However, administrators who want to update between two even-numbered minor versions can do so incurring only a single reboot of non-control plane hosts.

Warning

This update was previously known as an EUS-to-EUS update and is now referred to as a Control Plane Only update. These updates are only viable between even-numbered minor versions of OpenShift Container Platform.

There are several caveats to consider when attempting a Control Plane Only update.

Control Plane Only updates are only offered after updates between all versions involved have been made available in stable channels.
If you encounter issues during or after updating to the odd-numbered minor version but before updating to the next even-numbered version, then remediation of those issues may require that non-control plane hosts complete the update to the odd-numbered version before moving forward.
You can do a partial update by updating the worker or custom pool nodes to accommodate the time it takes for maintenance.
Until the machine config pools are unpaused and the update is complete, some features and bugs fixes in <4.y+1> and <4.y+2> of OpenShift Container Platform are not available.
All the clusters might update using EUS channels for a conventional update without pools paused, but only clusters with non control-plane MachineConfigPools objects can do Control Plane Only updates with pools paused.

Performing Control Plane Only updates¶

You can perform a Control Plane Only update by pausing all non-master machine config pools, performing updates from OpenShift Container Platform <4.y> to <4.y+1> to <4.y+2>, then unpausing the machine config pools.

Following these procedures reduces the total update duration and the number of times worker nodes are restarted.

Before performing a Control Plane Only update, ensure that you meet the following prerequisites:

You reviewed the release notes for OpenShift Container Platform <4.y+1> and <4.y+2>.
You reviewed the release notes and product lifecycles for any layered products and Operator Lifecycle Manager (OLM) Operators. Some products and OLM Operators might require updates either before or during a Control Plane Only update.
You are familiar with version-specific prerequisites, such as the removal of deprecated APIs, that are required before updating from OpenShift Container Platform <4.y+1> to <4.y+2>.
If your cluster uses in-tree vSphere volumes, you updated vSphere to version 7.0u3L+ or 8.0u2+.

Warning

If you do not update vSphere to 7.0u3L+ or 8.0u2+ before initiating an OpenShift Container Platform update, known issues might occur with your cluster after the update. For more information, see "Known Issues with OpenShift 4.12 to 4.13 or 4.13 to 4.14 vSphere CSI Storage Migration".

Additional resources

Known Issues with OpenShift 4.12 to 4.13 or 4.13 to 4.14 vSphere CSI Storage Migration

Control Plane Only update using the web console¶

You can perform a Control Plane Only update by using the web console.

Prerequisites

You verified that machine config pools are unpaused.
You have access to the web console as a user with cluster-admin privileges.

Procedure

Using the web console, update any Operator Lifecycle Manager (OLM) Operators to the versions that are compatible with your intended updated version. For more information, see "Updating installed Operators".
Verify that all machine config pools display a status of Up to date and that no machine config pool displays a status of UPDATING.

To view the status of all machine config pools, click Compute → MachineConfigPools and review the contents of the Update status column.

Note

If your machine config pools have an Updating status, wait for this status to change to Up to date. This process could take several minutes.
Set your channel to eus-<4.y+2>.

To set your channel, click Administration → Cluster Settings → Channel. You can edit your channel by clicking on the current hyperlinked channel.
Pause all worker machine pools except for the master pool. You can perform this action on the MachineConfigPools tab under the Compute page. Select the vertical ellipses next to the machine config pool you’d like to pause and click Pause updates.
Update to version <4.y+1> and complete up to the Save step. For more information, see "Updating a cluster by using the web console".
Ensure that the <4.y+1> updates are complete by viewing the Last completed version of your cluster. You can find this information on the Cluster Settings page under the Details tab.
If necessary, update your OLM Operators by using the Administrator perspective on the web console. For more information, see "Updating installed Operators".
Update to version <4.y+2> and complete up to the Save step. For more information, see "Updating a cluster by using the web console".
Ensure that the <4.y+2> update is complete by viewing the Last completed version of your cluster. You can find this information on the Cluster Settings page under the Details tab.
Unpause all previously paused machine config pools. You can perform this action on the MachineConfigPools tab under the Compute page. Select the vertical ellipses next to the machine config pool you’d like to unpause and click Unpause updates.

Warning

If pools are paused, the cluster is not permitted to upgrade to any future minor versions, and some maintenance tasks are inhibited. This puts the cluster at risk for future degradation.
Verify that your previously paused pools are updated and that your cluster has completed the update to version <4.y+2>.

You can verify that your pools have updated on the MachineConfigPools tab under the Compute page by confirming that the Update status has a value of Up to date.

Warning

When you update a cluster that contains Red Hat Enterprise Linux (RHEL) compute machines, those machines temporarily become unavailable during the update process. You must run the upgrade playbook against each RHEL machine as it enters the NotReady state for the cluster to finish updating. For more information, see "Updating a cluster that includes RHEL compute machines".

You can verify that your cluster has completed the update by viewing the Last completed version of your cluster. You can find this information on the Cluster Settings page under the Details tab.

Additional resources

Control Plane Only update using the CLI¶

You can perform a Control Plane Only update by using the OpenShift CLI (oc).

Prerequisites

You verified that machine config pools are unpaused.
You have access to the OpenShift Container Platform web console as a user with cluster-admin privileges.
You updated the OpenShift CLI (oc) to the target version before each update.

Warning

It is highly discouraged to skip this prerequisite. If the OpenShift CLI (oc) is not updated to the target version before your update, unexpected issues may occur.

Procedure

Using the web console, update any Operator Lifecycle Manager (OLM) Operators to the versions that are compatible with your intended updated version. For more information on how to perform this action, see "Updating installed Operators".

Verify that all machine config pools display a status of UPDATED and that no machine config pool displays a status of UPDATING. To view the status of all machine config pools, run the following command:

$ oc get mcp

Example output

NAME     CONFIG                                             UPDATED   UPDATING
master   rendered-master-ecbb9582781c1091e1c9f19d50cf836c       True      False
worker   rendered-worker-00a3f0c68ae94e747193156b491553d5       True      False

Your current version is <4.y>, and your intended version to update is <4.y+2>. Change to the eus-<4.y+2> channel by running the following command:
```
$ oc adm upgrade channel eus-<4.y+2>
```
Note

If you receive an error message indicating that eus-<4.y+2> is not one of the available channels, this indicates that Red Hat is still rolling out EUS version updates. This rollout process generally takes 45-90 days starting at the GA date.
Pause all worker machine pools except for the master pool by running the following command:
```
$ oc patch mcp/worker --type merge --patch '{"spec":{"paused":true}}'
```
Note

You cannot pause the master pool.
Update to the latest version by running the following command:
```
$ oc adm upgrade --to-latest
```
Example output
```
Updating to latest version <4.y+1.z>
```
Review the cluster version to ensure that the updates are complete by running the following command:
```
$ oc adm upgrade
```
Example output
```
Cluster version is <4.y+1.z>
...
```
Update to version <4.y+2> by running the following command:
```
$ oc adm upgrade --to-latest
```
Retrieve the cluster version to ensure that the <4.y+2> updates are complete by running the following command:
```
$ oc adm upgrade
```
Example output
```
Cluster version is <4.y+2.z>
...
```
To update your worker nodes to <4.y+2>, unpause all previously paused machine config pools by running the following command:
```
$ oc patch mcp/worker --type merge --patch '{"spec":{"paused":false}}'
```
Warning

If pools are not unpaused, the cluster is not permitted to update to any future minor versions, and some maintenance tasks are inhibited. This puts the cluster at risk for future degradation.
Verify that your previously paused pools are updated and that the update to version <4.y+2> is complete by running the following command:
```
$ oc get mcp
```
Warning

When you update a cluster that contains Red Hat Enterprise Linux (RHEL) compute machines, those machines temporarily become unavailable during the update process. You must run the upgrade playbook against each RHEL machine as it enters the NotReady state for the cluster to finish updating. For more information, see "Updating a cluster that includes RHEL compute machines" in the additional resources section.
Example output
```
NAME       CONFIG                                            UPDATED     UPDATING
master   rendered-master-52da4d2760807cb2b96a3402179a9a4c    True    False
worker   rendered-worker-4756f60eccae96fb9dcb4c392c69d497    True    False
```

Additional resources

Updating installed Operators

Control Plane Only updates for layered products and Operators installed through Operator Lifecycle Manager¶

There are additional steps to consider when performing Control Plane Only updates for clusters with either layered products or Operators installed through Operator Lifecycle Manager (OLM).

Layered products refer to products that are made of multiple underlying products that are intended to be used together and cannot be broken into individual subscriptions. For examples of layered OpenShift Container Platform products, see "Layered Offering On OpenShift".

As you perform a Control Plane Only update for the clusters of layered products and those of Operators that have been installed through OLM, you must complete the following actions:

You have updated all Operators previously installed through Operator Lifecycle Manager (OLM) to a version that is compatible with your target release. Updating the Operators ensures they have a valid update path when the default software catalogs switch from the current minor version to the next during a cluster update. See "Updating installed Operators" for more information on how to check compatibility and, if necessary, update the installed Operators.
Confirm the cluster version compatibility between the current and intended Operator versions. To verify which versions your OLM Operators are compatible with, see "Red Hat OpenShift Container Platform Operator Update Information Checker".

For example, the following high level steps describe how to perform a Control Plane Only update from <4.y> to <4.y+2> for OpenShift Data Foundation (ODF). This can be done through the CLI or web console. For information about how to update clusters through your desired interface, see "Control Plane Only update using the web console" and "Control Plane Only update using the CLI".

Pause the worker machine pools.
Update OpenShift Container Platform from <4.y> to <4.y+1>.
Update ODF from <4.y> to <4.y+1>.
Update OpenShift Container Platform from <4.y+1> to <4.y+2>.
Update ODF to <4.y+2>.
Unpause the worker machine pools.

Note

The update to ODF <4.y+2> can happen before or after worker machine pools have been unpaused.

Additional resources