demo2_k8soperator_golang

Demo application containing Kubernetes (K8s) Operator solution in pure Golang.

Prerequisites

Entire playbook assumes that you are using Windows 11 OS and PowerShell as CLI and in some stages Linux WSL.

• Go
• Kubectl
• Kind
• Docker
• Kubebuilder

Getting Started

All the steps require Linux WSL with the following version:

wsl --list --verbose
  NAME              STATE           VERSION
* Ubuntu-22.04      Running         2
  docker-desktop    Running         2

The current Linux WSL distro is:

lsb_release -a

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 22.04.5 LTS
Release:        22.04
Codename:       jammy

1. Manually install the prerequisites

   • kubebuilder

     mkdir -p <path/to/codebase/>/bin
     cd <path/to/codebase/>/bin
     curl -L -o kubebuilder https://github.com/kubernetes-sigs/kubebuilder/releases/download/v4.9.0/kubebuilder_linux_amd64
     chmod +x kubebuilder
     ./kubebuilder version
     sudo cp -avx kubebuilder /usr/local/bin/kubebuilder
     which kubebuilder
     kubebuilder version
     

   • use standard Linux approach to install Go, kubectl, kind, and docker

     Versions:

     # Go SDK
     go version
     go version go1.24.5 linux/amd64
     
     # kubectl
     Client Version: v1.34.1
     Kustomize Version: v5.7.1
     Server Version: v1.32.0
     
     # kind 
     kind version
     kind v0.22.0 go1.20.13 linux/amd64
     
     # docker
     docker version
     
     Client:
     Version:           28.4.0
     API version:       1.51
     Go version:        go1.24.7
     Git commit:        d8eb465
     Built:             Wed Sep  3 20:56:28 2025
     OS/Arch:           linux/amd64
     Context:           default
     
     Server: Docker Desktop 4.47.0 (206054)
     Engine:
     Version:          28.4.0
     API version:      1.51 (minimum version 1.24)                                                                                                                                                                    Go version:       go1.24.7
     Git commit:       249d679
     Built:            Wed Sep  3 20:57:37 2025
     OS/Arch:          linux/amd64
     Experimental:     false
     containerd:
     Version:          1.7.27
     GitCommit:        05044ec0a9a75232cad458027ca83437aae3f4da
     runc:
     Version:          1.2.5
     GitCommit:        v1.2.5-0-g59923ef
     docker-init:
     Version:          0.19.0
     GitCommit:        de40ad0
     

2. Clone the repository

   cd <path/to/codebase>/
   git clone https://github.com/norbix/demo2_k8soperator_golang.git
   

3. Start Docker Desktop

   Start-Process "C:\Program Files\Docker\Docker\Docker Desktop.exe" -WindowStyle Minimized

4. Start K8s cluster

   kind create cluster --name demo2-k8soperator-golang && \
   sleep 3 && \
   kind get clusters && \
   sleep 3 && \
   kubectl cluster-info && \
   sleep 3 && \
   kubectl config get-contexts && \
   kubectl get ns

5. Scaffold project

   kubebuilder init --domain norbix.io --repo github.com/norbix/demo2-k8soperator-golang --project-name demo2-k8soperator-golang

6. Create new operator

   kubebuilder create api --group core --version v1 --kind ConfigMapCopy --controller --resource=false

7. Manual E2E tests

   • Make sure your target namespace exists:

     kubectl create ns backup

   • Run the operator locally:

     make run

   • Create a ConfigMap in the default namespace:

     kubectl create configmap demo --from-literal=foo=bar

   • Logs should show:

     📄 Created backup ConfigMap source=default/demo copy=backup/demo-copy

   • Sanity Check:

   kubectl get cm -n backup

8. Deployment of the K8s Operator

   make docker-build IMG=norbix/demo2-k8soperator-golang:latest && \
   sleep 3 && \
   make docker-push IMG=norbix/demo2-k8soperator-golang:latest && \
   sleep 3 && \
   make deploy IMG=norbix/demo2-k8soperator-golang:latest && \
   kubectl get all -n demo2-k8soperator-golang-system

✅ Summary

You now have a fully functional operator that:

• Watches all ConfigMaps

• Copies them into a backup namespace

• Keeps them in sync

• Avoids infinite loops