Upgrading and rolling back releases in Kubernetes - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of upgrading a release in Kubernetes?

Upgrading a release means updating an application or service to a newer version to add features, fix bugs, or improve performance without stopping the whole system.

beginner

How do you perform an upgrade of a Helm release?

Use the command helm upgrade <release-name> <chart> to update the release with a new chart or configuration.

beginner

What does rolling back a release mean?

Rolling back means returning an application to a previous working version if the current upgrade causes problems.

beginner

Which Helm command is used to rollback a release?

The command helm rollback <release-name> [revision] is used to revert to a previous release version.

intermediate

Why is it important to keep track of release revisions in Kubernetes?

Keeping track of revisions helps you quickly restore a stable version if an upgrade fails, ensuring minimal downtime and service reliability.

Which command upgrades a Helm release?

A kubectl rollback <release-name>

B helm rollback <release-name>

C kubectl upgrade <release-name>

D helm upgrade <release-name> <chart>

The correct command to upgrade a Helm release is 'helm upgrade '.

What does 'helm rollback' do?

A Updates the release to a new version

B Deletes the release

C Reverts the release to a previous version

D Shows the release status

'helm rollback' reverts the release to a previous version if the current one has issues.

Why might you need to rollback a release?

A To add new features

B To fix a failed upgrade

C To delete the application

D To scale the application

Rollback is used to fix problems caused by a failed upgrade by restoring a stable version.

What is a release revision in Helm?

A A version of the release configuration

B A Helm plugin

C A type of Kubernetes pod

D A backup of the cluster

A release revision is a saved version of the release configuration that can be restored.

Which tool is commonly used to manage upgrades and rollbacks in Kubernetes?

A Helm

B Docker

C kubectl

D Minikube

Helm is the package manager for Kubernetes that handles upgrades and rollbacks of releases.

Explain the process and commands used to upgrade and rollback a release in Kubernetes using Helm.

Think about how you update an app and how you fix it if the update breaks something.

Describe why tracking release revisions is important in managing Kubernetes applications.

Consider how saving versions helps you undo mistakes.

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