Updating a cluster that includes RHEL compute machines

You can update, or upgrade, an {product-title} cluster. If your cluster contains Red Hat Enterprise Linux (RHEL) machines, you must perform more steps to update those machines.

Prerequisites

Have access to the cluster as a user with admin privileges. See Using RBAC to define and apply permissions.
Have a recent etcd backup in case your update fails and you must restore your cluster to a previous state.
Support for {op-system-base}7 workers is removed in {product-title} {product-version}. You must replace {op-system-base}7 workers with {op-system-base}8 or {op-system} workers before upgrading to {product-title} {product-version}. Red Hat does not support in-place {op-system-base}7 to {op-system-base}8 upgrades for {op-system-base} workers; those hosts must be replaced with a clean operating system install.
If your cluster uses manually maintained credentials, update the cloud provider resources for the new release. For more information, including how to determine if this is a requirement for your cluster, see Preparing to update a cluster with manually maintained credentials.
If you run an Operator or you have configured any application with the pod disruption budget, you might experience an interruption during the upgrade process. If minAvailable is set to 1 in PodDisruptionBudget, the nodes are drained to apply pending machine configs which might block the eviction process. If several nodes are rebooted, all the pods might run on only one node, and the PodDisruptionBudget field can prevent the node drain.