Revision management in GCP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

Understanding Cloud Run Revision Behavior

You deploy a new revision of a Cloud Run service. What happens to the previous revision?

A The previous revision is automatically scaled down to zero and removed after 24 hours.

B The previous revision is deleted immediately to save resources.

C The previous revision is archived and cannot be accessed anymore.

D The previous revision remains available and can receive traffic if configured.

💡 Hint

Think about how Cloud Run manages traffic between revisions.

Cloud Run keeps previous revisions available so you can route traffic to them if needed. They are not deleted automatically.

❓ Configuration

intermediate

Traffic Splitting Between Revisions in Cloud Run

You want to split traffic 70% to the latest revision and 30% to the previous revision in Cloud Run. Which configuration snippet correctly sets this?

A {"traffic": [{"revisionName": "rev-1", "percent": 70}, {"revisionName": "rev-2", "percent": 30}]}

B {"traffic": [{"revisionName": "rev-2", "percent": 70}, {"revisionName": "rev-1", "percent": 30}]}

C {"traffic": [{"revisionName": "rev-2", "percent": 30}, {"revisionName": "rev-1", "percent": 70}]}

D {"traffic": [{"revisionName": "rev-1", "percent": 30}, {"revisionName": "rev-2", "percent": 70}]}

💡 Hint

Latest revision is usually the one you want to get 70% traffic.

The configuration must assign 70% to the latest revision (rev-2) and 30% to the previous (rev-1). The order in the array does not matter but the percentages must match.

❓ Architecture

advanced

Designing a Rollback Strategy Using Cloud Run Revisions

You want to design a system that can quickly rollback to a previous stable version of your Cloud Run service if the latest deployment fails. Which approach best supports this?

A Keep previous revisions and use traffic splitting to route 100% traffic back to the stable revision.

B Manually edit the service to rename the previous revision as the latest.

C Use Cloud Build triggers to automatically rollback on failure.

D Delete the latest revision and redeploy the previous revision from source code.

💡 Hint

Think about how Cloud Run manages revisions and traffic routing.

Cloud Run allows you to keep previous revisions and route traffic to them instantly without redeploying. This enables fast rollback by shifting traffic back.

❓ security

advanced

Security Implications of Retaining Old Revisions in Cloud Run

What is a potential security risk of keeping multiple old revisions active in Cloud Run?

A Old revisions consume all available CPU resources causing denial of service.

B Old revisions automatically expose admin credentials to all users.

C Old revisions may have outdated code with vulnerabilities accessible if traffic is routed to them.

D Old revisions disable HTTPS causing unencrypted traffic.

💡 Hint

Consider what happens if old code has security flaws.

Keeping old revisions active means they can still receive traffic. If they have security flaws, attackers might exploit them if routed traffic reaches them.

✅ Best Practice

expert

Managing Revision Limits and Cleanup in Cloud Run

Cloud Run retains up to 1000 revisions per service. What is the best practice to manage revision cleanup to avoid hitting this limit?

A Manually delete old revisions regularly using gcloud or console to keep the count low.

B Ignore the limit as Cloud Run automatically deletes oldest revisions when limit is reached.

C Configure Cloud Run to auto-delete revisions older than 7 days via service settings.

D Disable revision retention so only the latest revision is kept automatically.

💡 Hint

Check how Cloud Run handles revision limits and what control you have.

Cloud Run does not auto-delete old revisions automatically. You must manually delete old revisions to avoid hitting the limit and potential deployment failures.