Delete a cluster machine using the management console

This section instructs you on how to scale down an existing management or MOSK cluster through the MOSK management console.

To delete a machine from a cluster using web UI:

  1. Carefully read the machine deletion precautions.

  2. Ensure that the machine being deleted is not a Ceph Monitor. If it is, migrate the Ceph Monitor to keep the odd number quorum of Ceph Monitors after the machine deletion. For details, see Remove a Ceph node.

  3. Log in to the MOSK management console with the m:kaas:namespace@operator or m:kaas:namespace@writer permissions.

  4. Click the More action icon in the last column of the machine you want to delete and select Delete.

  5. Select the machine deletion method:

    • Graceful

      Recommended. The machine will be prepared for deletion with all workloads safely evacuated. Using this option, you can cancel the deletion before the corresponding node is removed from Docker Swarm.

    • Unsafe

      Not recommended. The machine will be deleted without any preparation.

    • Forced

      Not recommended. The machine will be deleted with no guarantee of resources cleanup. Therefore, Mirantis recommends trying Graceful or Unsafe option first.

    For deletion workflow of each method, see Overview of machine deletion policies.

  6. Confirm the deletion.

  7. If machine deletion fails, you can reduce the deletion policy restrictions and try another method but in the following order only: Graceful > Unsafe > Forced.

  8. Strongly recommended. Back up MKE as described in Create backups of Mirantis Kubernetes Engine.

    Since the procedure above modifies the cluster configuration, a fresh backup is required to restore the cluster in case further reconfigurations fail.

    Important

    Because the MKE restoration process is complicated, we strongly recommend contacting Mirantis support for assistance.

    If you still decide to restore MKE from a backup on your own, you must scale down helm-controller on the cluster being restored if the MKE version of the affected cluster after the restore will differ from the MKE version in the ClusterRelease object that is set in MOSK Cluster objects in the management cluster:

    • If you are restoring MKE on a management cluster: before starting the restore, scale down helm-controller on each affected MOSK cluster. This prevents unintended Ceph and OpenStack downgrades on MOSK clusters after the management cluster is restored.

    • If you are restoring MKE on a MOSK cluster: immediately after the restore completes, scale down helm-controller. Because the restore rolls the cluster back to an older release, this prevents it from triggering a premature upgrade of Helm releases.

See also

Delete a cluster machine using CLI