How do you update an existing Deployment to use a new image tag?

• A. Delete the deployment and recreate with the new image tag.
• B. Edit the Deployment YAML manually and apply changes.
• C. Use oc set image deployment/<name> <container>=<image:tag>, or edit YAML and apply, or trigger ImageChange.
• D. Rebuild the application and redeploy the entire cluster.

Answer: (C)

Updating a Deployment to use a new image tag is done by performing a rolling update on the Deployment’s Pod template. This means changing the image reference for the container in the Deployment so that Kubernetes/OpenShift gradually replaces old pods with new ones running the updated image, without taking the app offline.

You can do this in a few straightforward ways. One common method is using the OpenShift CLI: oc set image deployment/ =image:tag. This updates the image for that container and triggers a new rollout that replaces pods with the new version. Another valid approach is to edit the Deployment YAML (specifically spec.template.spec.containers[].image) to the new image:tag and apply the changes; this also starts a rolling update. You can also configure an ImageChange trigger so that an update to the image stream automatically triggers a deployment, enabling automatic rollouts in CI/CD workflows.

Deleting the deployment and recreating it is not desirable because it disrupts the running application and bypasses the controlled rolling update process. Rebuilding the entire cluster is unnecessary for updating a single deployment’s image.