# Hello World - Go + PostgreSQL + Next.js

Full-stack Hello World application using Go backend, PostgreSQL database, and Next.js frontend.

## Project Structure

```
.
├── backend/          # Go API server
│   ├── main.go
│   ├── go.mod
│   └── Dockerfile
├── frontend/         # Next.js application
│   ├── app/
│   ├── package.json
│   └── Dockerfile
├── docker-compose.yml
└── README.md
```

## Quick Start with Docker

```bash
docker-compose up --build
```

Services:
- Frontend: http://localhost:3000
- Backend API: http://localhost:8080
- PostgreSQL: localhost:5432

## Manual Setup

### Backend (Go)

```bash
cd backend
go mod tidy
DB_HOST=localhost DB_PORT=5432 DB_USER=postgres DB_PASSWORD=postgres DB_NAME=hellodb go run main.go
```

### Frontend (Next.js)

```bash
cd frontend
npm install
NEXT_PUBLIC_API_URL=http://localhost:8080 npm run dev
```

### PostgreSQL

```bash
docker run -d \
  --name hello-postgres \
  -e POSTGRES_USER=postgres \
  -e POSTGRES_PASSWORD=postgres \
  -e POSTGRES_DB=hellodb \
  -p 5432:5432 \
  postgres:16-alpine
```

## API Endpoints

| Endpoint | Method | Description |
|----------|--------|-------------|
| `/api/hello` | GET | Returns hello message and DB status |
| `/api/health` | GET | Health check |

## Tech Stack

- **Backend**: Go 1.21
- **Database**: PostgreSQL 16
- **Frontend**: Next.js 14, React 18, TypeScript

## CI/CD Pipeline

### Woodpecker CI

`.woodpecker.yaml` файл нь дараах алхмуудыг гүйцэтгэнэ:

1. **build-backend** - Go backend Docker image build
2. **build-frontend** - Next.js frontend Docker image build
3. **push-backend** - Harbor registry рүү backend push
4. **push-frontend** - Harbor registry рүү frontend push
5. **update-manifests** - Kubernetes manifest дахь image tag шинэчлэх
6. **notify** - Deployment notification

### ArgoCD (GitOps)

ArgoCD application тохируулах:

```bash
kubectl apply -f argocd-application.yaml -n argocd
```

ArgoCD нь `manifests/` directory-г автоматаар sync хийнэ.

## Kubernetes Deployment

### Manifests

```
manifests/
├── namespace.yaml           # hell-world namespace
├── postgres-secret.yaml     # Database credentials
├── postgres-pvc.yaml        # PostgreSQL storage
├── postgres-deployment.yaml # PostgreSQL deployment
├── postgres-service.yaml    # PostgreSQL service
├── backend-deployment.yaml  # Go backend deployment
├── backend-service.yaml     # Backend service
├── frontend-deployment.yaml # Next.js frontend deployment
├── frontend-service.yaml    # Frontend service
├── ingress.yaml             # Ingress with TLS
└── kustomization.yaml       # Kustomize config
```

### Manual Deploy

```bash
kubectl apply -k manifests/
```

### URLs (Production)

- Frontend: https://hell-world.gecore.mn
- Backend API: https://hell-world-api.gecore.mn