Upgrading and rolling back releases in Kubernetes - Step-by-Step Execution

Process Flow - Upgrading and rolling back releases

Start: Current Release

↓

Upgrade Command

↓

New Release Deployed

↓

Check Release Status

↓

Keep New

↓

End

↓

End

This flow shows how a release is upgraded, checked, and if it fails, rolled back to the previous version.

Execution Sample

Kubernetes

helm upgrade myapp ./mychart
helm status myapp
helm rollback myapp 1

Upgrade a Helm release, check its status, and rollback to revision 1 if needed.

Process Table

Step	Command	Action	Result	Next Step
1	helm upgrade myapp ./mychart	Deploy new release version	New release deployed as revision 2	Check release status
2	helm status myapp	Check if new release is healthy	Release status: FAILED	Rollback release
3	helm rollback myapp 1	Restore previous release version	Rolled back to revision 1	End
4	-	End of process	Release stable at revision 1	-

💡 Rollback completed because new release failed health check

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
Release Revision	1	2	2 (failed)	1 (rolled back)	1 (stable)
Release Status	DEPLOYED	DEPLOYED	FAILED	DEPLOYED	DEPLOYED

Key Moments - 3 Insights

Why do we check the release status after upgrading?

Because the upgrade might fail or cause issues; checking status (step 2) tells us if rollback is needed.

What does 'helm rollback myapp 1' do exactly?

It restores the release to revision 1, the last stable version before the upgrade (step 3).

Can we skip rollback if the status is OK?

Yes, if the status check shows success, we keep the new release and do not rollback (not shown here but implied).

Visual Quiz - 3 Questions

Look at the execution table, what is the release revision after step 1?

A 3

B 1

C 2

D Failed

💡 Hint

Check the 'Release Revision' in variable_tracker after Step 1

At which step does the rollback happen?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look at the 'Command' column in execution_table for rollback command

If the release status was OK at step 2, what would happen next?

A Keep new release and end process

B Rollback to revision 1

C Upgrade again

D Delete release

💡 Hint

Refer to the concept_flow where success leads to keeping the new release

Concept Snapshot

helm upgrade <release> <chart>  # Deploy new version
helm status <release>             # Check release health
helm rollback <release> <rev>    # Restore previous version
Always check status after upgrade
Rollback if upgrade fails

Full Transcript

This visual execution shows how to upgrade a Helm release and rollback if needed. First, the upgrade command deploys a new release version (revision 2). Then, the status is checked. If the status is failed, a rollback command restores the previous stable revision (revision 1). The process ends with a stable release. Key points: always check status after upgrade and rollback if problems occur.

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