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Lab 10.3 - Creating a Custom Chart

Lab Objectives​

By the end of this lab, you will be able to:

  • Create a Helm Chart with helm create.
  • Understand the structure of a Chart.
  • Modify templates.
  • Use values in templates.
  • Package and install your Chart.

Estimated Duration​

60-75 minutes

Prerequisites​

  • Helm installed and configured.
  • Local Kubernetes cluster running.
  • Knowledge of Helm Charts (Chapter 10.3).

Part 1: Creating a Chart​

Step 1.1: Create a New Chart​

Create a new Chart:

helm create my-app-chart

Examine the structure:

tree my-app-chart
# or
ls -la my-app-chart/

Part 2: Chart Structure​

Step 2.1: Examine the Files​

Examine the main files:

# Chart.yaml
cat my-app-chart/Chart.yaml

# values.yaml
cat my-app-chart/values.yaml

# Templates
ls my-app-chart/templates/

Part 3: Customizing the Chart​

Step 3.1: Modify Chart.yaml​

Edit my-app-chart/Chart.yaml:

apiVersion: v2
name: my-app-chart
description: A custom Helm Chart for my application
type: application
version: 0.1.0
appVersion: "1.0"

Step 3.2: Modify values.yaml​

Edit my-app-chart/values.yaml:

replicaCount: 2

image:
  repository: nginx
  pullPolicy: IfNotPresent
  tag: "1.20"

service:
  type: ClusterIP
  port: 80

ingress:
  enabled: false

Part 4: Modifying Templates​

Step 4.1: Examine a Template​

Look at the Deployment template:

cat my-app-chart/templates/deployment.yaml

Step 4.2: Customize the Template​

Modify the template to add environment variables:

# In deployment.yaml, add in the container:
env:
- name: APP_NAME
  value: {{ .Values.nameOverride | default .Chart.Name }}

Part 5: Testing and Installation​

Step 5.1: Validate the Chart​

Validate the syntax:

helm lint my-app-chart

Step 5.2: Dry-Run​

Test without installing:

helm install my-app my-app-chart --dry-run --debug

Step 5.3: Install the Chart​

Install your Chart:

helm install my-app my-app-chart

Verify:

helm list
kubectl get all -l app.kubernetes.io/instance=my-app

Part 6: Packaging​

Step 6.1: Package the Chart​

Create a package:

helm package my-app-chart

This creates a .tgz file.

Step 6.2: Install from the Package​

Install from the package:

helm install my-app-from-package my-app-chart-0.1.0.tgz

Part 7: Cleanup​

helm uninstall my-app my-app-from-package
rm -rf my-app-chart my-app-chart-0.1.0.tgz

Lab Summary​

In this lab, you created your first custom Helm Chart. You learned the structure of a Chart, how to modify templates, and how to package your Chart.

Next Steps​

The last lab of this module will show you how to use Helmfile for multi-environment management.

Lab 10.4: Helmfile and Multi-environments

Lab created on: December 2024