kustomize-diff

README

Kustomize Diff

A tool to track and display field changes in Kubernetes resources when applying Kustomize patches.

Overview

Kustomize Diff helps you understand how your Kustomize patches modify Kubernetes resources by tracking and displaying the changes made to each field. It's particularly useful when you have multiple patches or complex kustomization structures and want to see exactly how each field is modified.

Features

• Tracks field changes across multiple patches
• Shows original and new values for each modified field
• Supports both file-based and inline patches
• Works with nested kustomizations and components
• Displays changes in a clear, hierarchical format

Installation

go install github.com/malc0lm/kustomize-diff@latest

Usage

Basic usage:

kustomize-diff <kustomization-dir>

Show final kustomize output:

kustomize-diff -show-final <kustomization-dir>

Example Output

Field Changes:
spec → replicas: 1 → 3
spec → template → spec → containers → 0 → image: test:1.0 → test:2.0

Example Kustomization Structure

.
├── kustomization.yaml
├── base/
│   ├── kustomization.yaml
│   └── deployment.yaml
└── patches/
    └── patch1.yaml

Example Files

base/deployment.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: test
spec:
  replicas: 1
  template:
    spec:
      containers:
      - name: test
        image: test:1.0

patches/patch1.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: test
spec:
  replicas: 3
  template:
    spec:
      containers:
      - name: test
        image: test:2.0

kustomization.yaml:

resources:
  - base
patches:
  - path: patches/patch1.yaml
    target:
      kind: Deployment
      name: test

Development

Prerequisites

• Go 1.16 or later
• Kustomize v4.0 or later

Building from Source

git clone https://github.com/malc0lm/kustomize-diff.git
cd kustomize-diff
go build

Running Tests

go test -v

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• Kustomize - The Kubernetes native configuration management tool
• Go - The programming language used