README.md

Kubernetes Custom Resource Definition (CRD) Example

This repository is a fork of https://github.com/martin-helmich/kubernetes-crd-example

The yaml files and the golang codes updated to align with below versions

• golang (>= 1.20.3)
• kubernetes (>= 1.26.11)

Table of contents

• Download
• Setup
• (Re) Generate golang source code (Optional)
• Build
• Run
  • Create crd and Watch
  • Make change to the CRD object

Download

git clone https://github.com/HaesungSeo/kubernetes-crd-example.git

Setup

go mod init github.com/martin-helmich/kubernetes-crd-example
go mod tidy

(Re) Generate golang source code (Optional)

cd api/types/v1alpha1/
go generate

Build

go build

Run

Create crd and Watch

Before run the watcher, execute below sequences

cd kubernetes
kubectl apply -f crd.yaml

Run the watcher!

./kubernetes-crd-example

Make change to the CRD object

Open another terminal then run it!

cd kubernetes
cat project.yaml | kubectl apply -f-
cat project.yaml | sed 's/replicas:.*/replicas: 2/g' | kubectl apply -f-
cat project.yaml | sed 's/replicas:.*/replicas: 3/g' | kubectl apply -f-
cat project.yaml | sed 's/replicas:.*/replicas: 4/g' | kubectl apply -f-

See the watcher's screen dump!

$ ./kubernetes-crd-example
2024/04/11 13:53:39 Using kubeconfig file:  /home/rocky/.kube/config
0 projects found:

2024/04/11 13:53:46 ADDED: example-project
2024/04/11 13:53:46   spec.replicas 1
2024/04/11 13:55:36 MODIFIED: example-project
2024/04/11 13:55:36   spec.replicas 2
2024/04/11 13:55:40 MODIFIED: example-project
2024/04/11 13:55:40   spec.replicas 3
2024/04/11 13:55:47 MODIFIED: example-project
2024/04/11 13:55:47   spec.replicas 4