Using Kustomize Kubernetes Configuration Management

Introduction

Kustomize Kubernetes is a powerful tool for managing Kubernetes configurations. Unlike other templating tools, Kustomize allows you to customize Kubernetes YAML configurations without using templates.

This article will guide you through the basics of using Kustomize, its key features, and practical examples to help streamline your Kubernetes configuration management.

What is Kustomize Kubernetes?

Kustomize is a configuration management tool that lets you customize Kubernetes resource files. It works by layering modifications on top of existing Kubernetes manifests, enabling you to maintain reusable and composable configurations. Kustomize is built into kubectl, making it easy to integrate into your Kubernetes workflows.

Key Features of Kustomize

• No Templating: Modify YAML files directly without templates.
• Layered Configurations: Apply different overlays for various environments (development, staging, production).
• Reusability: Use base configurations across multiple environments.
• Customization: Easily customize configurations with patches and strategic merge patches.

Getting Started with Kustomize

To get started with Kustomize, you need to understand its basic concepts: bases, overlays, and customization files.

Base Configuration

A base configuration is a set of common Kubernetes manifests. Here’s an example structure:

my-app/
  ├── base/
  │   ├── deployment.yaml
  │   ├── service.yaml
  │   └── kustomization.yaml

The kustomization.yaml file in the base directory might look like this:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - deployment.yaml
  - service.yaml

Overlay Configuration

Overlays are used to customize the base configuration for specific environments. Here’s an example structure for a development overlay:

my-app/
  ├── overlays/
  │   └── dev/
  │       ├── deployment-patch.yaml
  │       ├── kustomization.yaml
  ├── base/
      ├── deployment.yaml
      ├── service.yaml
      └── kustomization.yaml

The kustomization.yaml file in the dev overlay directory might look like this:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - ../../base
patchesStrategicMerge:
  - deployment-patch.yaml

And the deployment-patch.yaml might contain:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 2

Applying Kustomize Configurations

To apply the Kustomize configuration, navigate to the overlay directory and use the kubectl command:

kubectl apply -k overlays/dev

This command will apply the base configuration with the modifications specified in the dev overlay.

Advanced Kustomize Features

ConfigMap and Secret Generators: Kustomize can generate ConfigMaps and Secrets from files or literals.

configMapGenerator:
  - name: my-config
    files:
      - config.properties

Image Customization: Override image names and tags for different environments.

images:
  - name: my-app
    newName: my-app
    newTag: v2.0.0

Common Labels and Annotations: Add common labels and annotations to all resources.

commonLabels:
  app: my-app

Best Practices for Using Kustomize

• Organize Directories: Maintain a clear directory structure for bases and overlays.
• Reuse Configurations: Use base configurations to avoid duplication and ensure consistency.
• Version Control: Store Kustomize configurations in version control systems for easy collaboration and rollback.
• Testing: Test your configurations in a staging environment before applying them to production.

Conclusion

Kustomize is an invaluable tool for managing Kubernetes configurations efficiently. By using Kustomize, you can create reusable, layered configurations that simplify the deployment process across multiple environments. Embrace Kustomize to enhance your Kubernetes workflows and maintain clean, maintainable configurations. Thank you for reading the DevopsRoles page!