Kubernetes Controller

My implementation of the Golang Kubernetes Controller course from FWDays.

About

This project follows the step-by-step tutorial for building production-grade Kubernetes controllers in Go. Each step is implemented as a separate commit/branch with detailed explanations.

Course: Crash Course: Kubernetes controllers Instructors: @den-vasyliev (Principal SRE), @Alex0M (Senior Platform Engineer)

Quick Start

Prerequisites

• Go 1.23.1+ - Installation guide
• Taskfile - Installation guide
• Podman - Installation guide
• Docker (optional) - Alternative to Podman

One-Command Setup

Get a complete Kubernetes development environment running in seconds:

```bash

Clone the repository

git clone https://github.com/Searge/k8s-controller.git cd k8s-controller

Initialize Podman machine and provision Kubernetes cluster

task init && task ssh -- 'cd /srv/app && go-task provision'

Access your cluster

task ssh kubectl get nodes kubectl get all -A ```

This automated setup creates:

• Podman machine with Fedora CoreOS
• Complete single-node Kubernetes cluster (v1.30.0)
• All control plane components (etcd, API server, scheduler, controller-manager)
• Kubelet with containerd runtime
• CNI networking with bridge plugin
• PKI infrastructure with auto-generated certificates

Development Environment

The project includes a fully automated Kubernetes cluster setup for realistic controller development and testing. See ansible/README.md for detailed information about:

• Automated cluster provisioning
• Component configuration
• Available Ansible tags for selective deployment
• Troubleshooting and logging

Available Tasks

The project uses Taskfile for task automation:

```bash

View all available tasks

task

Development workflow

task dev # Format, lint, test, build task test-watch # Run tests in watch mode task docker-build # Build Docker image

Environment management

task init # Create and setup Podman machine task ssh # SSH into the machine task provision # Run Ansible provisioning task reboot # Restart the machine task rm # Remove the machine ```

Progress

• [x] Foundation

  • [x] Golang CLI Application using Cobra
  • [x] Structured logging with zerolog
  • [x] HTTP server with FastHTTP
  • [x] Comprehensive testing suite
  • [x] Quality assurance with linters
  • [x] Development environment automation
  • [x] Documentation and examples

• [ ] Kubernetes Integration (Next Steps)

  • [ ] List Kubernetes Deployments with client-go
  • [ ] Deployment Informer with client-go
  • [ ] JSON API Endpoint for deployments
  • [ ] controller-runtime Deployment Controller
  • [ ] Leader Election and Metrics

• [ ] Advanced Features (Future)

  • [ ] Custom Resource (FrontendPage CRD)
  • [ ] Platform API (CRUD + Swagger)
  • [ ] JWT Authentication
  • [ ] OpenTelemetry Instrumentation
  • [ ] Helm Charts and GitOps

Architecture

```mermaid C4Container title Kubernetes Controller Architecture

Person(user, "DevOps Engineer", "Uses CLI")

System_Boundary(app, "Controller Application") {
    Container(cli, "CLI Client", "Go, Cobra", "Command line interface")
    Container(server, "HTTP Server", "Go, FastHTTP", "REST API and UI")
    Container(controller, "Controller", "Go, controller-runtime", "Reconciliation logic")
    Container(informers, "Informers", "Go, client-go", "Watch and cache")
}

System_Ext(k8s, "Kubernetes API", "Manages cluster resources")

Rel(user, cli, "Uses")
Rel(cli, server, "Commands")
Rel(server, k8s, "API calls")
Rel(k8s, informers, "Events")
Rel(informers, controller, "Cached data")
Rel(controller, k8s, "Reconcile")

```

Project Structure

bash ├── ansible/ # Kubernetes cluster automation │ ├── README.md # Detailed Ansible documentation │ ├── init.yml # Initial system setup │ ├── provision.yml # Main K8s provisioning │ └── templates/ # Service and config templates ├── cmd/ # CLI application code ├── notebooks/ # Go learning notebooks ├── scripts/ # Setup and utility scripts ├── Taskfile.yaml # Task automation ├── Dockerfile # Container image definition └── README.md # This file

📚 Documentation

• API Documentation - HTTP endpoints and CLI commands

🔗 Resources

• Course: Kubernetes Controllers Crash Course
• Reference: Tutorial Reference Implementation
• Go Style: Google Go Style Guide
• Kubernetes: client-go Documentation

📄 License

This project is licensed under the GNU General Public License v3.0 - see the LICENSE file for details.

Built with ❤️ by @Searge