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.

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

   Copy to Clipboard Toggle word wrap

   Example output

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

   1

   Copy to Clipboard Toggle word wrap

   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. Shut down all of the nodes in the cluster. You can do this from your cloud provider’s web console, or run the following loop:

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

   1

   Copy to Clipboard Toggle word wrap

   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 10 minutes 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.

   Copy to Clipboard Toggle word wrap

   Shutting down the nodes using one of these methods allows pods to terminate gracefully, which reduces the chance for data corruption.

   Note

   Adjust the shut down time to be longer for large-scale clusters:

   $ for node in $(oc get nodes -o jsonpath='{.items[*].metadata.name}'); do oc debug node/${node} -- chroot /host shutdown -h 10; done

   Copy to Clipboard Toggle word wrap
   Note

   It is not necessary to drain control plane nodes (also known as the master 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.

3. 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.