The operator takes a Pod down to restart and applies a new configuration value. All Pods are restarted in reverse ordinal order.

WhenupdateStrategy is not present in the specification, it defaults to the following:

spec:  updateStrategy:    type: "RollingUpdate"    rollingUpdate:      partition: 0      maxUnavailable: 1

1. TheRollingUpdate strategy will update Pods one by one in reverse ordinal order.
2. This means that all the Pods from ordinal Replicas-1 topartition are updated . You can split the update into partitions to performcanary rollout.
3. This ensures that the cluster has no more than one unavailable Pod at any given point in time.

spec:  updateStrategy:    type: "OnDelete"

OnDelete strategy does not automatically update Pods when a modification is made. You need to restart Pods yourself.