In case of a Deployment failure, which Kubernetes command can be used to revert to a functioning version?

In case of a Deployment failure, which Kubernetes command can be used to revert to a functioning version?

• A. kubectl rollout undo deployment/<name>
• B. kubectl rollback deployment/<name>
• C. kubectl scale deployment/<name> --replicas=1
• D. kubectl patch deployment <name> -p ...

Answer: (A)

Rolling back a failed Deployment uses the rollout history to restore a previous working state. Kubernetes records each Deployment update as a new revision with its own ReplicaSet, so undoing returns you to the prior revision, effectively replacing the current ReplicaSet with the previous one and adjusting replicas as needed. You can simply run kubectl rollout undo deployment/<name>, which by default reverts to the last good revision; you can also target a specific revision with --to-revision if needed. The other options don’t perform a rollback. There is no kubectl rollback command for deployments, so that won’t revert to a prior revision. Scaling to a single replica only changes the number of pods and does not restore the previous rollout state. Patching the deployment changes the spec, but it doesn’t revert to an earlier revision from rollout history.

Rolling back a failed Deployment uses the rollout history to restore a previous working state. Kubernetes records each Deployment update as a new revision with its own ReplicaSet, so undoing returns you to the prior revision, effectively replacing the current ReplicaSet with the previous one and adjusting replicas as needed. You can simply run kubectl rollout undo deployment/, which by default reverts to the last good revision; you can also target a specific revision with --to-revision if needed.

The other options don’t perform a rollback. There is no kubectl rollback command for deployments, so that won’t revert to a prior revision. Scaling to a single replica only changes the number of pods and does not restore the previous rollout state. Patching the deployment changes the spec, but it doesn’t revert to an earlier revision from rollout history.