Uninstall MKE¶

MKE is designed to scale as your applications grow in size and usage. You can add and remove nodes from the cluster to make it scale to your needs.

You can also uninstall MKE from your cluster. In this case, the MKE services are stopped and removed, but your Mirantis Container Runtimes will continue running in swarm mode. You applications will continue running normally.

If you wish to remove a single node from the MKE cluster, you should instead remove that node from the cluster.

After you uninstall MKE from the cluster, you’ll no longer be able to enforce role-based access control (RBAC) to the cluster, or have a centralized way to monitor and manage the cluster. After uninstalling MKE from the cluster, you will no longer be able to join new nodes using docker swarm join, unless you reinstall MKE.

To uninstall MKE, log in to a manager node using ssh, and run the following command:

docker container run --rm -it \
  -v /var/run/docker.sock:/var/run/docker.sock \
  --name ucp \
  mirantis/ucp:3.3.16 uninstall-ucp --interactive

This runs the uninstall command in interactive mode, so that you are prompted for any necessary configuration values.

If the uninstall-ucp command fails, you can run the following commands to manually uninstall MKE:

#Run the following command on one manager node to remove remaining MKE services
docker service rm $(docker service ls -f name=ucp- -q)

#Run the following command on each manager node to remove remaining MKE containers
docker container rm -f $(docker container ps -a -f name=ucp- -f name=k8s_ -q)

#Run the following command on each manager node to remove remaining MKE volumes
docker volume rm $(docker volume ls -f name=ucp -q)

The MKE configuration is kept in case you want to reinstall MKE with the same configuration. If you want to also delete the configuration, run the uninstall command with the --purge-config option.

Refer to the CLI Reference documentation to see the available options.

Once the uninstall command finishes, MKE is completely removed from all the nodes in the cluster. You don’t need to run the command again from other nodes.

Swarm mode CA¶

After uninstalling MKE, the nodes in your cluster will still be in swarm mode, but you can’t join new nodes until you reinstall MKE, because swarm mode relies on MKE to provide the CA certificates that allow nodes in the cluster to identify one another. Also, since swarm mode is no longer controlling its certificates, if the certificates expire after you uninstall MKE, the nodes in the swarm won’t be able to communicate at all. To fix this, either reinstall MKE before the certificates expire or disable swarm mode by running docker swarm leave --force on every node.

Restore IP tables¶

When you install MKE, the Calico network plugin changes the host’s IP tables. When you uninstall MKE, the IP tables aren’t reverted to their previous state. After you uninstall MKE, restart the node to restore its IP tables.