Helm charts concept in Kubernetes - Commands & Configuration

Introduction

Managing Kubernetes applications can be complex because they require many files and settings. Helm charts help by packaging all these files into one easy-to-use bundle, making it simple to install, update, or remove applications on Kubernetes.

When you want to deploy a web application with multiple Kubernetes resources like deployments, services, and config maps all at once.

When you need to share your Kubernetes application setup with others in a reusable and version-controlled way.

When you want to upgrade your application smoothly without manually changing each Kubernetes file.

When you want to roll back to a previous version of your application easily if something goes wrong.

When you want to manage complex applications with many configuration options in a simple way.

Config File - Chart.yaml

Chart.yaml

apiVersion: v2
name: my-app
description: A simple Helm chart for Kubernetes
version: 0.1.0
appVersion: 1.0.0

apiVersion: Helm chart version format.

name: The chart name.

description: A short explanation of the chart.

version: The chart package version.

appVersion: The version of the app this chart deploys.

Commands

This command creates a new Helm chart named 'my-app' with a basic folder structure and example files to start with.

Terminal

helm create my-app

Expected Output

Creating new chart 'my-app'

This installs the 'my-app' chart into your Kubernetes cluster, creating all the resources defined in the chart.

Terminal

helm install my-app ./my-app

Expected Output

NAME: my-app

LAST DEPLOYED: Sat Jun 10 12:00:00 2023

NAMESPACE: default

STATUS: deployed

REVISION: 1

NOTES:

1. Get the application URL by running these commands:

  export POD_NAME=$(kubectl get pods --namespace default -l "app.kubernetes.io/name=my-app,app.kubernetes.io/instance=my-app" -o jsonpath='{.items[0].metadata.name}')

  echo "Visit http://127.0.0.1:8080 to use your application"

  kubectl port-forward $POD_NAME 8080:80

This command shows all Helm releases installed in the current Kubernetes cluster and namespace.

Terminal

helm list

Expected Output

NAME    NAMESPACE   REVISION    UPDATED                     STATUS      CHART         APP VERSION

my-app  default     1           2023-06-10 12:00:00.000000  deployed    my-app-0.1.0  1.0.0

This removes the 'my-app' release and deletes all Kubernetes resources created by it.

Terminal

helm uninstall my-app

Expected Output

release "my-app" uninstalled

Key Concept

If you remember nothing else from this pattern, remember: Helm charts package Kubernetes resources into one reusable bundle to simplify app deployment and management.

Common Mistakes

Trying to install a Helm chart without creating or downloading it first.

Helm needs the chart files locally or from a repository to install; without them, it cannot deploy anything.

Run 'helm create my-app' to create a chart or 'helm repo add' and 'helm repo update' to get charts from a repository before installing.

Not checking the status of the Helm release after installation.

You might think the app is running when it failed to deploy properly, causing confusion and wasted time.

Use 'helm list' or 'helm status my-app' to verify the release status and troubleshoot if needed.

Manually editing Kubernetes resources created by Helm instead of updating the chart.

Helm manages resources based on the chart; manual changes can be overwritten or cause conflicts during upgrades.

Update the Helm chart templates or values and use 'helm upgrade' to apply changes cleanly.

Summary

Use 'helm create' to generate a new chart with a ready folder structure.

Install the chart with 'helm install' to deploy your app and its resources to Kubernetes.

Check installed releases with 'helm list' to see what is running.

Remove apps cleanly with 'helm uninstall' to delete all related resources.

Practice

1. What is the primary purpose of a Helm chart in Kubernetes?

easy

A. To replace kubectl commands

B. To monitor Kubernetes cluster health

C. To package and deploy Kubernetes applications easily

D. To create Docker images

Solution

1. Step 1: Understand Helm chart role

   A Helm chart bundles Kubernetes app resources for easy deployment and sharing.

2. Step 2: Compare options

   Options B, C, and D describe other tools or tasks unrelated to Helm charts.

3. Final Answer:

   To package and deploy Kubernetes applications easily -> Option C

4. Quick Check:

   Helm chart = package & deploy app [OK]

Hint: Helm charts bundle apps for easy deployment [OK]

Common Mistakes:

• Confusing Helm with monitoring tools
• Thinking Helm replaces kubectl entirely
• Assuming Helm builds Docker images

2. Which Helm command is used to create a new chart skeleton?

easy

A. helm rollback

B. helm install

C. helm upgrade

D. helm create

Solution

1. Step 1: Identify command purpose

   helm create generates a new chart directory with default files.

2. Step 2: Eliminate other commands

   helm install deploys charts, helm upgrade updates releases, helm rollback reverts upgrades.

3. Final Answer:

   helm create -> Option D

4. Quick Check:

   New chart skeleton = helm create [OK]

Hint: Use helm create to start a chart [OK]

Common Mistakes:

• Using helm install to create charts
• Confusing upgrade with create
• Trying rollback to create charts

3. Given the command helm install myapp ./mychart, what happens?

medium

A. Installs the release 'myapp' using the chart from the local directory './mychart'

B. Creates a new chart named 'myapp' in './mychart'

C. Upgrades the release 'myapp' with './mychart'

D. Rolls back the release 'myapp' to './mychart'

Solution

1. Step 1: Understand helm install syntax

   helm install [release-name] [chart-path] deploys the chart as a release.

2. Step 2: Analyze given command

   Here, 'myapp' is the release name, './mychart' is the chart directory to deploy.

3. Final Answer:

   Installs the release 'myapp' using the chart from the local directory './mychart' -> Option A

4. Quick Check:

   helm install = deploy chart [OK]

Hint: helm install deploys chart as release [OK]

Common Mistakes:

• Thinking install creates charts
• Confusing install with upgrade or rollback
• Misunderstanding release name vs chart path

4. You run helm upgrade myapp ./mychart but get an error: "release: not found". What is the likely cause?

medium

A. The release 'myapp' does not exist yet

B. The chart path './mychart' is invalid

C. You need to use helm install instead of upgrade

D. The Kubernetes cluster is down

Solution

1. Step 1: Understand helm upgrade error

   The error "release: not found" means the named release does not exist in the cluster.

2. Step 2: Identify correct cause

   Since upgrade updates existing releases, trying to upgrade a non-existent release causes this error.

3. Final Answer:

   The release 'myapp' does not exist yet -> Option A

4. Quick Check:

   Upgrade needs existing release [OK]

Hint: Upgrade fails if release not installed yet [OK]

Common Mistakes:

• Assuming chart path error causes this message
• Using upgrade instead of install for new release
• Blaming cluster status without checking release

5. You want to deploy a Helm chart and be able to easily revert to the previous version if needed. Which Helm commands should you use in order?

hard

A. helm create, helm install, helm rollback

B. helm install, helm upgrade, helm rollback

C. helm create, helm upgrade, helm rollback

D. helm install, helm create, helm rollback

Solution

1. Step 1: Understand deployment and version control

   First, use helm install to deploy the initial release.

2. Step 2: Manage updates and rollback

   Use helm upgrade to update the release, and helm rollback to revert if needed.

3. Step 3: Eliminate incorrect sequences

   helm create is for making charts, not deployment steps. It should not be in the deploy/rollback sequence.

4. Final Answer:

   helm install, helm upgrade, helm rollback -> Option B

5. Quick Check:

   Install -> Upgrade -> Rollback = C [OK]

Hint: Install first, then upgrade, rollback if needed [OK]

Common Mistakes:

• Using helm create in deployment sequence
• Skipping install before upgrade
• Confusing rollback with create