Chapter 2. Shutting down the cluster gracefully

Procedure

1. If you are shutting the cluster down for an extended period, determine the date on which certificates expire and run the following command:

   $ oc -n openshift-kube-apiserver-operator get secret kube-apiserver-to-kubelet-signer -o jsonpath='{.metadata.annotations.auth\.openshift\.io/certificate-not-after}'

   Example output

   2022-08-05T14:37:50Zuser@user:~ $ 1

   1

   To ensure that the cluster can restart gracefully, plan to restart it on or before the specified date. As the cluster restarts, the process might require you to manually approve the pending certificate signing requests (CSRs) to recover kubelet certificates.

2. Mark all the nodes in the cluster as unschedulable. You can do this from your cloud provider’s web console, or by running the following loop:

   $ for node in $(oc get nodes -o jsonpath='{.items[*].metadata.name}'); do echo ${node} ; oc adm cordon ${node} ; done

   Example output

   ci-ln-mgdnf4b-72292-n547t-master-0
   node/ci-ln-mgdnf4b-72292-n547t-master-0 cordoned
   ci-ln-mgdnf4b-72292-n547t-master-1
   node/ci-ln-mgdnf4b-72292-n547t-master-1 cordoned
   ci-ln-mgdnf4b-72292-n547t-master-2
   node/ci-ln-mgdnf4b-72292-n547t-master-2 cordoned
   ci-ln-mgdnf4b-72292-n547t-worker-a-s7ntl
   node/ci-ln-mgdnf4b-72292-n547t-worker-a-s7ntl cordoned
   ci-ln-mgdnf4b-72292-n547t-worker-b-cmc9k
   node/ci-ln-mgdnf4b-72292-n547t-worker-b-cmc9k cordoned
   ci-ln-mgdnf4b-72292-n547t-worker-c-vcmtn
   node/ci-ln-mgdnf4b-72292-n547t-worker-c-vcmtn cordoned

3. Evacuate the pods using the following method:

   $ for node in $(oc get nodes -l node-role.kubernetes.io/worker -o jsonpath='{.items[*].metadata.name}'); do echo ${node} ; oc adm drain ${node} --delete-emptydir-data --ignore-daemonsets=true --timeout=15s --force ; done

4. Shut down all of the nodes in the cluster. You can do this from the web console for your cloud provider web console, or by running the following loop. Shutting down the nodes by using one of these methods allows pods to terminate gracefully, which reduces the chance for data corruption.

   Note

   Ensure that the control plane node with the API VIP assigned is the last node processed in the loop. Otherwise, the shutdown command fails.

   $ for node in $(oc get nodes -o jsonpath='{.items[*].metadata.name}'); do oc debug node/${node} -- chroot /host shutdown -h 1; done 1

   1

   -h 1 indicates how long, in minutes, this process lasts before the control plane nodes are shut down. For large-scale clusters with 10 nodes or more, set to -h 10 or longer to make sure all the compute nodes have time to shut down first.

   Example output

   Starting pod/ip-10-0-130-169us-east-2computeinternal-debug ...
   To use host binaries, run `chroot /host`
   Shutdown scheduled for Mon 2021-09-13 09:36:17 UTC, use 'shutdown -c' to cancel.
   Removing debug pod ...
   Starting pod/ip-10-0-150-116us-east-2computeinternal-debug ...
   To use host binaries, run `chroot /host`
   Shutdown scheduled for Mon 2021-09-13 09:36:29 UTC, use 'shutdown -c' to cancel.

   Note

   It is not necessary to drain control plane nodes of the standard pods that ship with OpenShift Container Platform prior to shutdown. Cluster administrators are responsible for ensuring a clean restart of their own workloads after the cluster is restarted. If you drained control plane nodes prior to shutdown because of custom workloads, you must mark the control plane nodes as schedulable before the cluster will be functional again after restart.

5. Shut off any cluster dependencies that are no longer needed, such as external storage or an LDAP server. Be sure to consult your vendor’s documentation before doing so.

   Important

   If you deployed your cluster on a cloud-provider platform, do not shut down, suspend, or delete the associated cloud resources. If you delete the cloud resources of a suspended virtual machine, OpenShift Container Platform might not restore successfully.