Google ACE Practice Question: Ensuring Successful Operation of a Cloud Solution
You notice that a deployment in your GKE cluster is running an outdated image. You need to update the deployment to use the new image 'gcr.io/my-project/my-app:v2'. Which kubectl command should you use?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
kubectl set image deployment/my-deployment my-app=gcr.io/my-project/my-app:v2
To update the image of a deployment, use 'kubectl set image' specifying the deployment name and the container name:tag.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
kubectl set image deployment/my-deployment my-app=gcr.io/my-project/my-app:v2
Why this is correct
kubectl set image deployment/my-deployment my-app=gcr.io/my-project/my-app:v2 is the correct imperative command to update a container image inside a Deployment. The container name (my-app) must exactly match the container name defined in the Deployment's pod spec, and the command updates the pod template so the Deployment controller creates a new ReplicaSet and performs a rolling update. This is the canonical kubectl syntax for changing an image without editing a manifest.
- ✗
kubectl rollout restart deployment my-deployment --image gcr.io/my-project/my-app:v2
Why it's wrong here
kubectl rollout restart deployment my-deployment --image gcr.io/my-project/my-app:v2 is invalid and conceptually wrong: the rollout restart subcommand does not support an --image flag, and even without that flag it would only add an annotation to trigger a new ReplicaSet using the existing pod template image. It is useful for restarting pods to re-pull the same image or re-read ConfigMaps, but it cannot change the container image to v2. Use kubectl set image to actually update the image.
- ✗
kubectl update deployment my-deployment --image gcr.io/my-project/my-app:v2
Why it's wrong here
kubectl update deployment my-deployment --image gcr.io/my-project/my-app:v2 is incorrect because kubectl update is not a valid subcommand; kubectl uses edit, apply, patch, replace, and set to modify resources. This command would fail with an unknown command error, and even if a hypothetical update subcommand existed, the --image flag is not part of its syntax. The correct imperative image update is kubectl set image deployment/my-deployment my-app=<new-image>.
- ✗
kubectl replace deployment my-deployment --image gcr.io/my-project/my-app:v2
Why it's wrong here
kubectl replace deployment my-deployment --image gcr.io/my-project/my-app:v2 is wrong because kubectl replace requires a YAML/JSON manifest file passed with -f and does not accept an --image flag; it overwrites the entire existing resource definition with the specified file contents. This command would fail with an unknown flag error and would not perform an incremental image update. A proper kubectl replace -f deployments.yaml would require the file to already contain the new image, making it a declarative replacement, not a simple image update.
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Related to this question
Learn chapter
Deployment Manager and Terraform on GCP
Key term
GKE
GKE is Google's managed Kubernetes service that automates deploying, scaling, and managing containerized applications in the cloud.
Key term
Container
A container is a lightweight, standalone software package that includes everything needed to run an application, such as code, runtime, system tools, and libraries.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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