Upgrading and rolling back releases in Kubernetes - Mini Project: Build & Apply

Upgrading and Rolling Back Releases in Kubernetes

📖 Scenario: You are managing a simple web application deployed on Kubernetes. You need to upgrade the application to a new version and then learn how to roll back to the previous version if something goes wrong.

🎯 Goal: Learn how to upgrade a Kubernetes deployment to a new version and roll back to the previous version using kubectl commands.

📋 What You'll Learn

A Kubernetes cluster with kubectl configured

A deployment named webapp running version v1

Basic knowledge of kubectl commands

💡 Why This Matters

🌍 Real World

In real projects, upgrading applications without downtime and rolling back quickly if issues occur is critical for smooth user experience.

💼 Career

DevOps engineers and site reliability engineers often manage application deployments and need to perform upgrades and rollbacks safely.

1

Create the initial deployment

Create a deployment named webapp with image nginx:1.19 using the command kubectl create deployment webapp --image=nginx:1.19.

Kubernetes

# Run the command to create the deployment
# Your code here

Hint

Use kubectl create deployment with the exact name webapp and image nginx:1.19.

2

Upgrade the deployment to a new version

Use the command kubectl set image deployment/webapp webapp=nginx:1.21 to upgrade the webapp deployment's container image to nginx:1.21.

Kubernetes

kubectl create deployment webapp --image=nginx:1.19
# Upgrade the deployment image to nginx:1.21
# Your code here

Hint

Use kubectl set image with deployment name webapp and container name webapp to set the image to nginx:1.21.

3

Roll back the deployment to the previous version

Use the command kubectl rollout undo deployment/webapp to roll back the webapp deployment to the previous version.

Kubernetes

kubectl create deployment webapp --image=nginx:1.19
kubectl set image deployment/webapp webapp=nginx:1.21
# Roll back the deployment to the previous version
# Your code here

Hint

Use kubectl rollout undo with the deployment name webapp to roll back.

4

Check the rollout status

Use the command kubectl rollout status deployment/webapp to check the status of the deployment rollout.

Kubernetes

kubectl create deployment webapp --image=nginx:1.19
kubectl set image deployment/webapp webapp=nginx:1.21
kubectl rollout undo deployment/webapp
# Check the rollout status
# Your code here

Hint

Use kubectl rollout status deployment/webapp to see if the deployment is successful.

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