Upgrading and rolling back releases in Kubernetes - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of Helm upgrade command with dry-run

What is the output of the following Helm command when upgrading a release with the --dry-run flag?

Kubernetes

helm upgrade myapp ./mychart --dry-run

A Deletes the current release and installs a new one with the same name

B Simulates the upgrade and shows the rendered Kubernetes manifests without applying changes

C Upgrades the release and immediately rolls back if any error occurs

D Shows the history of previous releases for the given release name

💡 Hint

Think about what the --dry-run flag does in Helm commands.

The --dry-run flag simulates the upgrade process and outputs the Kubernetes manifests that would be applied, without making any changes to the cluster.

🧠 Conceptual

intermediate

Understanding Helm rollback behavior

When you run helm rollback myapp 2, what happens?

A The release named 'myapp' is reverted to the state it had in revision 2

B The release 'myapp' is deleted and a new release is installed with revision 2

C The release 'myapp' is upgraded to the latest revision ignoring revision 2

D The rollback command shows the differences between current and revision 2 without changing anything

💡 Hint

Rollback means going back to a previous version.

The helm rollback command reverts the release to the specified revision, restoring the previous state of the application.

❓ Troubleshoot

advanced

Troubleshooting failed Helm upgrade

You ran helm upgrade myapp ./mychart but the upgrade failed and the release is in a failed state. What is the best next step to recover the application?

A Run <code>helm rollback myapp</code> to revert to the previous working release

B Delete the release with <code>helm delete myapp</code> and reinstall it

C Run <code>kubectl delete pods -l app=myapp</code> to restart the pods

D Run <code>helm upgrade myapp ./mychart --force</code> to force the upgrade

💡 Hint

Think about how to restore a stable state after a failed upgrade.

Rolling back the release restores the last known good state, which is the safest way to recover from a failed upgrade.

🔀 Workflow

advanced

Correct sequence for upgrading and verifying a Helm release

What is the correct order of commands to upgrade a Helm release and verify it is running correctly?

A 1,3,2,4

B 1,4,2,3

C 2,1,3,4

D 1,2,3,4

💡 Hint

Think about upgrading first, then checking pods, then release status, then detailed pod info.

First upgrade the release, then check pods to see if they are running, then check release status, and finally describe pods for detailed info if needed.

✅ Best Practice

expert

Best practice for managing Helm release rollbacks in production

Which practice is best to minimize downtime and risk when rolling back a Helm release in production?

A Immediately delete the release and reinstall the previous version to ensure a clean state

B Manually edit Kubernetes resources to match the previous version before rolling back

C Use <code>helm rollback</code> combined with readiness probes and monitor pod status before confirming rollback success

D Force upgrade with <code>helm upgrade --force</code> to overwrite any issues without rollback

💡 Hint

Think about automation and monitoring during rollback.

Combining rollback with readiness probes and monitoring ensures the application is healthy before considering rollback complete, minimizing downtime and risk.

Practice

1. What is the primary purpose of the helm upgrade command in Kubernetes?

easy

A. To create a new Helm release from scratch

B. To delete a Helm release from the cluster

C. To update an existing Helm release with a new version of the application

D. To list all Helm releases in the cluster

Solution

1. Step 1: Understand the role of helm upgrade

   This command is used to update an existing release with new chart or configuration changes.

2. Step 2: Differentiate from other Helm commands

   Unlike helm install which creates new releases, helm upgrade modifies existing ones.

3. Final Answer:

   To update an existing Helm release with a new version of the application -> Option C

4. Quick Check:

   Upgrade means update existing release [OK]

Hint: Upgrade means update existing release, not create or delete [OK]

Common Mistakes:

• Confusing upgrade with install
• Thinking upgrade deletes releases
• Assuming upgrade lists releases

2. Which of the following is the correct syntax to rollback a Helm release named myapp to revision 2?

easy

A. helm upgrade myapp --revision=2

B. helm rollback myapp 2

C. helm rollback --release myapp --rev 2

D. helm revert myapp 2

Solution

1. Step 1: Recall Helm rollback syntax

   The correct command is helm rollback RELEASE_NAME REVISION.

2. Step 2: Match syntax with options

   helm rollback myapp 2 matches the correct syntax exactly: helm rollback myapp 2.

3. Final Answer:

   helm rollback myapp 2 -> Option B

4. Quick Check:

   Rollback syntax is helm rollback name revision [OK]

Hint: Rollback uses: helm rollback release_name revision_number [OK]

Common Mistakes:

• Using helm upgrade instead of rollback
• Using incorrect flags like --revision
• Using nonexistent command 'helm revert'

3. Given the following commands executed in order:

helm install myapp ./chart
helm upgrade myapp ./chart --set image.tag=v2
helm rollback myapp 1
helm status myapp

What will be the image tag shown in the status output after the rollback?

medium

A. No image tag shown

B. v2 (tag set during upgrade)

C. v3 (latest tag automatically applied)

D. v1 (original tag from install)

Solution

1. Step 1: Understand the sequence of commands

   First, the app is installed with default image tag (assumed v1). Then upgraded to tag v2. Then rolled back to revision 1 (the original install).

2. Step 2: Determine image tag after rollback

   Rollback to revision 1 restores the original state, so image tag reverts to v1.

3. Final Answer:

   v1 (original tag from install) -> Option D

4. Quick Check:

   Rollback restores previous revision state [OK]

Hint: Rollback returns to previous revision state, undoing upgrades [OK]

Common Mistakes:

• Assuming rollback keeps upgraded tag
• Thinking rollback applies latest tag automatically
• Ignoring rollback effect on release state

4. You ran helm upgrade myapp ./chart --set replicas=3 but the number of pods did not change. What is the most likely cause?

medium

A. The chart does not use the replicas value to set pod count

B. You forgot to run helm rollback first

C. The helm upgrade command syntax is incorrect

D. The Kubernetes cluster is down

Solution

1. Step 1: Check if the chart supports the replicas value

   Not all charts use the replicas parameter; if the chart template ignores it, no change occurs.

2. Step 2: Rule out other causes

   Syntax is correct, rollback is unrelated, and cluster down would cause more errors.

3. Final Answer:

   The chart does not use the replicas value to set pod count -> Option A

4. Quick Check:

   Chart must support value for upgrade to affect it [OK]

Hint: Check if chart templates use your set values before expecting changes [OK]

Common Mistakes:

• Assuming all charts respond to replicas value
• Confusing rollback with upgrade necessity
• Blaming syntax when command is correct

5. You want to upgrade your Helm release webapp to version 3 of your chart but keep the previous configuration values intact except for changing the image tag to v3. Which command achieves this safely?

hard

A. helm upgrade webapp ./chart --reuse-values --set image.tag=v3

B. helm upgrade webapp ./chart --reset-values --set image.tag=v3

C. helm upgrade webapp ./chart --set image.tag=v3

D. helm rollback webapp 3 --set image.tag=v3

Solution

1. Step 1: Understand --reuse-values option

   This option keeps existing values from the previous release and applies new overrides.

2. Step 2: Compare with other options

   --reset-values resets to chart defaults, losing previous config. Omitting reuse-values loses previous config. Rollback does not upgrade.

3. Final Answer:

   helm upgrade webapp ./chart --reuse-values --set image.tag=v3 -> Option A

4. Quick Check:

   Use --reuse-values to keep old config and override selectively [OK]

Hint: Use --reuse-values with --set to keep config and update specific values [OK]

Common Mistakes:

• Using --reset-values and losing config
• Not using --reuse-values and losing previous settings
• Trying rollback to upgrade