What is Kustomize ?

What is Kustomize ?

In the dynamic realm of container orchestration, Kubernetes stands tall as the go-to platform for managing and deploying containerized applications. However, as the complexity of applications and infrastructure grows, so does the challenge of efficiently managing configuration files. Enter Kustomize, a powerful tool designed to simplify and streamline Kubernetes configuration management. In this blog post, we’ll delve into the world of Kustomize, unraveling its core concepts, benefits, and practical applications.

What is Kustomize

Kustomize is an open-source configuration management tool designed for Kubernetes. It empowers developers and operators to customize, patch, and manage Kubernetes manifests in a declarative manner. Unlike traditional templating engines, Kustomize focuses on patches and overlays, enabling users to make modifications to existing YAML files without altering the originals.

Understanding Kustomize:

At its core, Kustomize is a configuration management tool specifically crafted for Kubernetes. It provides a declarative approach to defining and customizing Kubernetes manifests, enabling users to parameterize and extend configurations without the need for extensive scripting or duplication.

Key Concepts:

Manifest Customization:

  • Kustomize operates by allowing users to overlay their base Kubernetes manifests with customizations. This is achieved through the use of “kustomization.yaml” files, where users can specify patches, variables, and other configuration details.

Patches and Overlays:

  • The true power of Kustomize lies in its ability to apply patches and overlays to base manifests. Patches can be used to modify or add specific elements within the manifests, making it easy to manage environment-specific configurations or implement changes across different deployment stages.

Variables and Configurations:

  • Kustomize introduces a structured way of managing variables, eliminating the need for tedious find-and-replace operations within manifests. This ensures consistency across deployments and simplifies the process of maintaining multiple configurations for development, staging, and production environments.

How Does Kustomize Work?

At its core, Kustomize utilizes a hierarchy of files and overlays to build, customize, and compose Kubernetes manifests. It functions by applying a series of patches or overlays on top of base manifests, allowing for configuration changes without modifying the original resources directly. This approach ensures cleaner, maintainable, and version-controlled configurations.

Benefits of Kustomize:


  • With Kustomize, managing Kubernetes configurations becomes more straightforward and maintainable. The separation of concerns between base manifests and customizations allows for cleaner, more modular configuration files.


  • Kustomize promotes the reuse of configuration snippets and overlays, reducing redundancy in your manifests. This not only saves time but also enhances consistency and reduces the likelihood of errors.

Environment-specific Configurations:

  • Easily adapt your Kubernetes manifests to different environments by utilizing Kustomize’s ability to apply environment-specific patches. This ensures seamless transitions between development, testing, and production environments.

Getting Started with Kustomize

  • Installation: Start by installing Kustomize, available as a standalone binary or as part of the kubectl toolset.

  • Basic Usage: Create a base configuration for your Kubernetes resources. Then, generate overlays for different environments or customizations.

  • Overlay Management: Utilize overlays to modify specific fields, add new resources, or apply patches without altering the original YAML files.

  • Integration: Incorporate Kustomize into your CI/CD pipelines to streamline application deployment across various environments. Follow RazorOps Linkedin Page Razorops, Inc.

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