In this article, We are going to cover Kubernetes Kustomize Tutorial for Beginners with Practical Examples.
Kustomize is a powerful tool that simplifies Kubernetes configuration management by enabling you to reuse and customize YAML files cleanly and declaratively. This all-in-one tutorial brings together key concepts, real-world examples, and advanced use cases to help you get started and grow with Kustomize.
Table of Contents
What is Kustomize?
Kustomize is a Kubernetes-native configuration management tool that allows you to customize raw, template-free YAML files. It works by layering configurations—called bases and overlays—to simplify deployment for different environments.
Core Concepts of Kustomize
- Base: Contains original manifests (e.g., Deployment, Service)
- Overlay: Applies customizations on top of the base (e.g., environment-specific changes)
- kustomization.yaml: The declarative file that controls everything
Kustomize Features:
- Template-free customization
- Base and overlay structure
- Strategic merge patches
- Reusable components
- Remote Git repository support
- Multi-environment workflows
- Native
kubectlsupport
Kustomize Components
1. kustomization.yaml:
The main configuration file in Kustomize where all resources, patches, and transformations are defined.
2. Resources:
Kubernetes manifests (like Deployments, Services, ConfigMaps) that define the objects Kustomize will customize. These can be local files or remote resources.
3. Patches:
Custom changes applied to existing resources. These can be strategic merge patches or JSON patches.
4. Transformers:
Components that modify or add metadata (like labels, annotations) to resources. For example, adding common labels or namespace to all resources.
5. Bases:
A base is a set of configurations that are shared across multiple overlays (environments). It contains common elements that can be reused.
6. Overlays:
Specific environment configurations (like dev, prod). Overlays modify the base configurations as needed for different environments.
7. Components:
Reusable units that can be imported into other Kustomizations. Components allow you to modularize common functionality (e.g., adding logging, monitoring).
8. Secrets and ConfigMaps:
Kustomize provides the ability to generate and manage Kubernetes Secrets and ConfigMaps directly from files.
Tools to Practice Kustomize
To effectively practice and implement Kustomize, consider utilizing the following tools:
Local Clusters
- Minikube: Run a single-node Kubernetes cluster locally.
- kind (Kubernetes IN Docker): Create lightweight Kubernetes clusters inside Docker containers.
Cluster Management
- Lens: A powerful IDE for Kubernetes that provides visualization and management capabilities, allowing you to test Kustomize overlays seamlessly.
Integration Tools
- kubectl kustomize: Built into
kubectl, enabling direct application of Kustomize configurations.
Online Platforms
- Katacoda: Offers interactive Kubernetes and Kustomize learning environments.
- Play with Kubernetes: Provides cloud-hosted clusters for practicing YAML configurations.
These tools facilitate hands-on experience with Kustomize, enhancing your understanding and proficiency in managing Kubernetes configurations.
Kustomize Tutorial for Beginners
We have categorized below Basic Practical Kustomize Tutorial for Beginners which will help to those who want to start learning Kustomize.
#1.Kubernetes Configurations with Kustomize Transformers with Examples
Transformers are key to how Kustomize applies changes. You can add common labels, annotations, and other metadata without editing every resource:
commonLabels:
app: myapp
commonAnnotations:
team: devops
This simplifies bulk customization and helps you maintain consistency.
#2.Managing Namespaces in Kubernetes with Kustomize
Setting a namespace at the Kustomization level ensures all resources are deployed under a specific namespace unless explicitly overridden:
namespace: dev
This is essential for environment separation in Kubernetes.
#3.How to Manage Common Labels and Annotations in Kustomize for Base and Overlays
Organize your manifests with shared metadata across base and overlay configurations:
commonLabels:
environment: staging
Kustomize ensures these are applied to all your resources cleanly.
#4.Strategic Merge Patches in Kubernetes using Kustomize
Use strategic merge patches to update specific fields in base resources without rewriting them entirely:
patchesStrategicMerge:
- patch.yaml
Example patch.yaml:
spec:
replicas: 3
This approach makes configurations flexible and DRY.
#5.Kubernetes Customization with Kustomize Components
Components are reusable units (like logging, monitoring) that can be applied across overlays:
components:
- ../components/logging
Perfect for microservices with shared features.
#6.Multi Environment Workflows in Kustomize
Organize your directory structure for environment-specific customization:
├── base/
├── overlays/
│ ├── dev/
│ ├── staging/
│ └── prod/
Each overlay modifies the base with specific changes like replicas or image versions.
#7.How to Use Kustomize with Remote Git Repositories
Reuse and consume configuration from Git repositories:
resources:
- github.com/your-org/your-repo//base/app?ref=main
This helps you manage a central config repo and avoid duplication.
#8.Helm vs Kustomize: Real-Time Examples
| Feature | Helm | Kustomize |
|---|---|---|
| Templating | Yes (Go templates) | No (declarative YAML only) |
| Learning Curve | Steeper | Beginner-friendly |
| Secrets/Values Injection | Via values.yaml | Via patches or generators |
| Tooling Integration | Wide ecosystem | Native in kubectl |
| Use Case | Complex apps, charts | Layered customization |
Real-world Use Case:
- Use Helm to deploy third-party tools like Prometheus.
- Use Kustomize to manage your in-house microservices with custom overlays.
Explore All Tutorials
🔗 Kubernetes Configurations with Kustomize Transformers with Examples
🔗 Managing Namespaces in Kubernetes with Kustomize
🔗 Strategic Merge Patches in Kubernetes using Kustomize
🔗 Kubernetes Customization with Kustomize Components
🔗 Multi Environment Workflows in Kustomize
🔗 How to Use Kustomize with Remote Git Repositories
🔗 Helm vs Kustomize: Real-Time Examples
Conclusion:
Kustomize makes managing Kubernetes manifests scalable, reusable, and environment-specific—without the complexity of templates. This tutorial provided insights into real-world scenarios such as using transformers to modify configurations, working with remote Git repositories, managing environments and overlays efficiently, leveraging components and patches for modular design, and comparing Kustomize with Helm to help make informed decisions.
Related Articles:
Kubernetes Tutorial for Beginners [20 Practical Articles]
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