Update a MOSK cluster to 21.6 or below

Once a Mirantis Container Cloud management cluster automatically upgrades to a new available Container Cloud release version, a newer version of a Cluster release becomes available for MOSK managed clusters.

This section instructs you on how to update your MOSK cluster using the Container Cloud web UI.


Make sure to update the Cluster release version of your managed cluster before the current Cluster release version becomes unsupported by a new Container Cloud release version. Otherwise, Container Cloud stops auto-upgrade and eventually Container Cloud itself becomes unsupported.

To update a MOSK cluster to 21.6 or below:

  1. Set the maintenance flag for Ceph:


    Starting from the MOSK 21.4 to 21.5 update, skip this step since it is automated. The maintenance flag is deprecated and will be removed from KaasCephCluster.

    1. Open the KaasCephCluster CR for editing:

      kubectl edit kaascephcluster
    2. Enable the maintenance flag:

          maintenance: true
  2. Log in to the Container Cloud web UI with the writer permissions.

  3. Switch to the required project using the Switch Project action icon located on top of the main left-side navigation panel.

  4. In the Clusters tab, click More action icon in the last column for each cluster and select Update cluster where available.

  5. In the Release Update window, select the required Cluster release to update your managed cluster to.

    The Description section contains the list of components versions to be installed with a new Cluster release.

  6. Click Update.

    Before the cluster update starts, Container Cloud performs a backup of MKE and Docker Swarm. The backup directory is located under:

    • /srv/backup/swarm on every Container Cloud node for Docker Swarm

    • /srv/backup/ucp on one of the controller nodes for MKE

    To view the update status, verify the cluster status on the Clusters page. Once the orange blinking dot near the cluster name disappears, the update is complete.

  7. After the update is complete, and if your MOSK managed cluster uses Tugsten Fabric as a back end for networking, manually restart the vRouter pods:

    1. Upgrade the vRouter pods by removing them one by one manually.


      Manual removal is required because vRouter pods use the OnDelete update strategy. vRouter pod restart causes networking downtime for workloads on the affected node. If it is not applicable for some workloads, migrate them before restarting the vRouter pods.

      kubectl -n tf delete pod <VROUTER-POD-NAME>
    2. Verify that all tf-vrouter-* pods are upgraded:

      kubectl -n tf get ds | grep tf-vrouter

      The UP-TO-DATE and CURRENT fields must have the same values.

  8. Disable the maintenance flag for Ceph from the KaasCephCluster CR once the update is complete and all nodes are in the Ready status:


    Starting from the MOSK 21.4 to 21.5 update, skip this step since it is automated. The maintenance flag is deprecated and will be removed from KaasCephCluster.

        maintenance: false


In rare cases, after a managed cluster update, Grafana may stop working due to the issues with helm-controller.

The development team is working on the issue that will be addressed in one of the following releases.


MKE and Kubernetes API may return short-term 50x errors during the update process. Ignore these errors.