Kustomize Basics

What You'll Learn

In this section, you'll learn the fundamental concepts of Kustomize:

• How to organize your Kubernetes configurations
• How to make simple changes without touching the original files
• Understanding base and overlay structure

Directory Structure

.
├── base/                  # Your original configuration
│   ├── deployment.yaml    # A basic nginx deployment
│   └── kustomization.yaml # Tells Kustomize what to include
└── overlay/              # Your customizations
    └── kustomization.yaml # Defines how to modify the base

Understanding the Files

Base Configuration

The base/ directory contains your original, unchanged configuration:

• deployment.yaml: A simple nginx web server deployment
• kustomization.yaml: Lists which files to include

Overlay Configuration

The overlay/ directory shows how to customize the base:

• Adds a prefix to all resources (dev-)
• Updates the nginx image version to 1.20
• Adds environment labels

Try It Yourself

1. View the base deployment:

kubectl kustomize base/

2. View the customized version:

kubectl kustomize overlay/

3. Apply to your cluster:

kubectl apply -k overlay/

What's Happening?

1. Kustomize reads the base configuration
2. It applies the changes specified in the overlay:
   • Adds "dev-" prefix to names
   • Updates the nginx image
   • Adds environment labels
3. Generates the final configuration

Key Concepts

• Base: Your original configuration
• Overlay: Your customizations
• kustomization.yaml: Tells Kustomize what to do
• Resources: The Kubernetes files you want to modify