Upgrade an operating system distribution¶

Available since MCC 2.24.0 (14.0.0)

Warning

During the course of the MOSK 24.3 series, Mirantis highly recommends upgrading an operating system on your cluster machines to Ubuntu 22.04 before the following major release becomes available.

It is not mandatory to upgrade all machines at once. You can upgrade them one by one or in small batches, for example, if the maintenance window is limited in time.

Otherwise, update of management or MOSK clusters running Ubuntu 20.04 will not be possible in the following major product version with Ubuntu 22.04 as the only supported version.

Warning

Usage of third-party software, which is not part of Mirantis-supported configurations, for example, the use of custom DPDK modules, may block upgrade of an operating system distribution. Users are fully responsible for ensuring the compatibility of such custom components with the latest supported Ubuntu version.

Distribution upgrade of an operating system (OS) is implemented for management and MOSK clusters.

For management clusters, an OS distribution upgrade occurs automatically since Container Cloud 2.24.0 (Cluster release 14.0.0) as part of cluster update and requires machines reboot. The upgrade workflow is as follows:

The distribution ID value is taken from the id field of the distribution from the allowedDistributions list in the spec of the ClusterRelease object.
The distribution that has the default: true value is used during update. This distribution ID is set in the spec:providerSpec:value:distribution field of the Machine object during cluster update.

For MOSK clusters, an in-place OS distribution upgrade should be performed between cluster updates. This scenario implies a machine cordoning, draining, and reboot.

Note

If you want to migrate container runtime on cluster machines from Docker to containerd and have not upgraded the OS distribution to Jammy yet, Mirantis recommends combining both procedures to minimize the maintenance window. In this case, ensure that all cluster machines are updated during one maintenance window to prevent machines from running different container runtimes.

Container runtime migration to containerd is available since Container Cloud 2.28.4 (Cluster releases 17.3.4 and 16.3.4). For details, see Migrate container runtime from Docker to containerd.

To upgrade an OS distribution on MOSK between releases:

Caution

A machine reboot occurs automatically during distribution update.

Open the required Machine object for editing.
In spec:providerSpec:value:distribution, set the required ID of the new OS version. For example, ubuntu/jammy.

For description of the Machine object fields, see Container Cloud documentation: API Reference.

The machine reboot occurs automatically after completion of deployment phases.
Once the distribution upgrade completes, verify that currentDistribution matches the distribution value previously set in the object spec. For description of the status fields, see Container Cloud documentation: API Reference.
Repeat the procedure with the remaining machines.
Optional. Available since Container Cloud 2.28.4 (Cluster releases 17.3.4 and 16.3.4). Upgrade container runtime from Docker to containerd together with distribution upgrade as described in Migrate container runtime from Docker to containerd to minimize the size of maintenance window.

Note

Container runtime migration becomes mandatory in the scope of Container Cloud 2.29.x. Otherwise, the management cluster update to Container Cloud 2.30.0 will be blocked.