nodes-pods-configuring-pod-critical.adoc

Preventing pod removal using critical pods

There are a number of core components that are critical to a fully functional cluster, but, run on a regular cluster node rather than the master. A cluster might stop working properly if a critical add-on is evicted.

Pods marked as critical are not allowed to be evicted.

,Procedure

To make a pod critical:

1. Create a pod specification or edit existing pods to include the system-cluster-critical priority class:

   spec:
     template:
       metadata:
         name: critical-pod
       priorityClassName: system-cluster-critical (1)

   1. Default priority class for pods that should never be evicted from a node.

Alternatively, you can specify system-node-critical for pods that are important to the cluster but can be removed if necessary.

1. Create the pod:

   $ oc create -f <file-name>.yaml