Rollback deployments in Firebase - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

Understanding Firebase Hosting Rollback Behavior

You deployed a new version of your Firebase Hosting site but noticed a critical bug. You want to rollback to the previous version quickly.

What happens when you run firebase hosting:rollback?

A It instantly switches the live site to the previous deployed version without downtime.

B It creates a new deployment identical to the previous version but does not switch traffic automatically.

C It deletes the current version and redeploys the previous version, causing downtime.

D It archives all versions but requires manual DNS changes to rollback.

💡 Hint

Think about how Firebase Hosting manages versions and traffic switching.

Firebase Hosting rollback instantly switches the live site to the previous deployed version without downtime by updating the serving configuration.

❓ Configuration

intermediate

Rollback Command Usage

You want to rollback your Firebase Hosting deployment to the version deployed 3 deployments ago.

Which command correctly rolls back to that specific version?

A firebase hosting:rollback --version-name 3

B firebase hosting:rollback --to 3

C firebase hosting:rollback 3

D firebase hosting:rollback --target 3

💡 Hint

Check the official Firebase CLI rollback command syntax.

The version number is specified as a positional argument: firebase hosting:rollback 3. Other flags are invalid.

❓ Architecture

advanced

Rollback Impact on CDN Cache

After rolling back a Firebase Hosting deployment, what happens to the cached content on the CDN edge servers?

A The rollback triggers a manual cache purge request that you must run separately.

B The CDN cache continues serving the old content until it expires naturally.

C The CDN cache is disabled temporarily during rollback to prevent stale content.

D The CDN cache is automatically invalidated and refreshed with the rollback version content.

💡 Hint

Consider how Firebase Hosting manages content freshness after deployment changes.

Firebase Hosting automatically invalidates CDN caches on rollback to ensure users get the correct content immediately.

❓ security

advanced

Rollback and Security Rules Consistency

You rolled back your Firebase Hosting deployment to a previous version. What happens to the Firebase Security Rules associated with the hosting content?

A Security Rules remain as they were in the current version and do not rollback automatically.

B Security Rules rollback automatically to the version associated with the hosting rollback.

C Security Rules are disabled temporarily until manually re-enabled after rollback.

D Security Rules are deleted and must be redeployed manually after rollback.

💡 Hint

Think about how Firebase separates hosting content from security rules deployment.

Firebase Security Rules are managed separately and do not rollback automatically with hosting content.

✅ Best Practice

expert

Rollback Strategy for Zero Downtime

You want to implement a rollback strategy for Firebase Hosting that guarantees zero downtime and quick recovery from faulty deployments.

Which approach best achieves this?

A Deploy a new version with fixes and manually update DNS records to point to it.

B Use Firebase Hosting's built-in rollback command to instantly switch versions without downtime.

C Delete the faulty deployment and redeploy the previous version from local files.

D Pause all traffic to the site, rollback, then resume traffic after verification.

💡 Hint

Consider the features Firebase Hosting provides for deployment management.

Firebase Hosting's rollback command instantly switches traffic to a previous version with no downtime, making it the best practice for quick recovery.

Practice

1.

What is the main purpose of firebase hosting:rollback?

easy

A. To deploy a new version of the website

B. To create a backup of the current deployment

C. To delete all hosting versions permanently

D. To undo a recent deployment and restore the previous version

Solution

1. Step 1: Understand rollback purpose

   Rollback is used to undo a deployment that caused issues by restoring the previous stable version.

2. Step 2: Identify command function

   The command firebase hosting:rollback specifically reverts to the last working deployment.

3. Final Answer:

   To undo a recent deployment and restore the previous version -> Option D

4. Quick Check:

   Rollback = undo deployment [OK]

Hint: Rollback means undo last deployment fast [OK]

Common Mistakes:

• Confusing rollback with deploying new versions
• Thinking rollback deletes all versions
• Assuming rollback creates backups

2.

Which of the following is the correct syntax to rollback the last Firebase Hosting deployment?

easy

A. firebase hosting:rollback

B. firebase rollback hosting

C. firebase deploy:rollback hosting

D. firebase hosting rollback --last

Solution

1. Step 1: Recall correct command structure

   The official Firebase CLI command for rollback is firebase hosting:rollback.

2. Step 2: Check option syntax

   Options B, C, and D do not match the correct Firebase CLI syntax for rollback.

3. Final Answer:

   firebase hosting:rollback -> Option A

4. Quick Check:

   Correct syntax = firebase hosting:rollback [OK]

Hint: Remember exact command: firebase hosting:rollback [OK]

Common Mistakes:

• Swapping command parts order
• Adding extra flags not needed
• Using deploy instead of hosting

3.

Given the deployment history shows versions v5, v6, and v7, with v7 currently live, what will firebase hosting:rollback do?

medium

A. Rollback to version v6

B. Rollback to version v7 again

C. Rollback to version v5

D. Delete all versions except v7

Solution

1. Step 1: Identify current live version

   The current live version is v7, the latest deployment.

2. Step 2: Understand rollback behavior

   Rollback reverts to the previous version before the current one, which is v6.

3. Final Answer:

   Rollback to version v6 -> Option A

4. Quick Check:

   Rollback = previous version v6 [OK]

Hint: Rollback always reverts to the immediate previous version [OK]

Common Mistakes:

• Choosing the oldest version instead of previous
• Thinking rollback redeploys current version
• Assuming rollback deletes versions

4.

You ran firebase hosting:rollback but got an error saying "No previous version found." What is the most likely cause?

medium

A. Firebase CLI is outdated

B. You have no prior deployments to rollback to

C. Your internet connection is down

D. You typed the command incorrectly

Solution

1. Step 1: Analyze error message meaning

   The error "No previous version found" means there is no earlier deployment saved to revert to.

2. Step 2: Consider possible causes

   This usually happens if this is the first deployment or all previous versions were deleted.

3. Final Answer:

   You have no prior deployments to rollback to -> Option B

4. Quick Check:

   No previous version = no rollback possible [OK]

Hint: No previous version means no rollback available [OK]

Common Mistakes:

• Assuming command syntax error
• Blaming network issues
• Ignoring deployment history

5.

You deployed version v10 but found a critical bug. You want to rollback to v9. However, v9 was deleted from the history. What is the best approach to recover your site quickly?

hard

A. Delete v10 and wait for Firebase to restore v9 automatically

B. Run firebase hosting:rollback to get v9 back

C. Redeploy a saved local copy of v9 manually

D. Contact Firebase support to restore v9

Solution

1. Step 1: Understand rollback limitations

   Rollback only works if the previous version exists in deployment history. Since v9 is deleted, rollback cannot restore it.

2. Step 2: Identify recovery method

   The best way is to redeploy a saved local copy of v9 manually to restore the stable version quickly.

3. Step 3: Evaluate other options

   Options B and C won't work because rollback needs the version present, and Firebase does not auto-restore deleted versions. Contact Firebase support to restore v9 may take too long for urgent fixes.

4. Final Answer:

   Redeploy a saved local copy of v9 manually -> Option C

5. Quick Check:

   Deleted version = manual redeploy needed [OK]

Hint: Rollback needs version history; redeploy local copy if missing [OK]

Common Mistakes:

• Expecting rollback to restore deleted versions
• Waiting for automatic Firebase restore
• Ignoring local backups