When implementing a blue/green deployment methodology in GKE, what action is required for rollback procedures?

In a blue/green deployment strategy, maintaining the ability to quickly roll back to a previous version of an application is a critical aspect. When a new version of the application is deployed (the green version), the goal is to minimize downtime and risk by having the previous version (the blue version) still running and ready to take over if necessary.

Updating the Kubernetes Service to point back to the previous Deployment is the correct action to take for rollback procedures. This process involves changing the service configuration to direct traffic back to the older version of the application seamlessly. Since the previous version is still deployed and running, this change can be made without having to start or stop container instances manually, ensuring a quick and smooth transition back to stability if issues are detected in the new version.

Other options like deleting the new container image and all running Pods or scaling the new Deployment to zero would not only be disruptive but could also complicate the rollback process. Running the kubectl rollout undo command is an alternative in Kubernetes, but in the context of blue/green deployments, manually managing service endpoints to point to the desired deployment version provides clearer control over traffic routing and user experience.