Rolling Software Update Using SMI Cluster Manager

The PCF software update or in-service update procedure utilizes the K8s rolling strategy to update the pod images. In K8s rolling update strategy, the pods of a StatefulSet are updates sequentially to ensure that the ongoing process remains unaffected. Initially, a rolling update on a StatefulSet causes a single pod instance to terminate. A pod with an updated image replaces the terminated pod. This process continues until all the replicas of the StatefulSet are updated. The terminating pods exit gracefully after competing all the ongoing processes. Other in-service pods continue to receive and process the traffic to provide a seamless software update. You can control the software update process through the Ops Center CLI.

Note

Each pod needs a minimum of two replicas for high availability. For example, Policy Engine must have 2 Engine replicas. In a worst-case scenario, the processing capacity of the pod may briefly reduce to 50% while the software update is in-progress.

The following figure illustrates a PCF rolling update for PCF REST endpoint pods (two replicas) on Protocol worker nodes along with PCF Service pods (three replicas) on Service worker nodes.

PCF Rolling Update