# Go gRPC Gateway Template

A production-ready Go template for gRPC services with HTTP/JSON gateway support, featuring modern tooling, Docker support, and CI/CD integration.

## 🚀 Features

- **Dual Protocol Support** - Serve both gRPC and REST APIs simultaneously
- **Modern Toolchain** - Uses [buf](https://buf.build) for Protocol Buffers management
- **Docker Ready** - Complete containerization with multi-stage builds
- **Testing** - Unit and integration tests with coverage
- **CI/CD** - GitHub Actions workflows for testing and deployment
- **Health Checks** - Built-in health monitoring endpoints
- **OpenAPI** - Auto-generated Swagger documentation
- **Configuration** - Environment-based config management
- **Observability** - Structured logging and metrics ready

## 📁 Project Structure

```
├── cmd/server/              # Main application entry point
├── proto/helloworld/        # Protocol buffer definitions
├── internal/
│   ├── config/             # Configuration management
│   ├── health/             # Health check handlers
│   └── server/             # Server setup and middleware
├── pkg/                    # Shared packages (if needed)
├── tests/                  # Integration tests
├── docker/                 # Docker configuration
├── .github/workflows/      # CI/CD pipelines
├── buf.yaml               # Buf configuration
├── buf.gen.yaml           # Code generation config
├── docker-compose.yml     # Local development
└── justfile              # Task runner
```

## 🛠 Prerequisites

- **Go 1.23+**
- **Docker & Docker Compose** (for containerized development)
- **[just](https://github.com/casey/just)** task runner
- **[buf](https://buf.build)** (installed automatically via `just install-deps`)

## 🚦 Quick Start

### 1. Install Dependencies
```bash
just install-deps
```

### 2. Start Development Environment
```bash
# Start with Docker (recommended)
just dev-docker

# Or start locally
just dev
```

### 3. Test the API
```bash
# gRPC endpoint
grpcurl -plaintext -d '{"name": "World"}' localhost:8080 helloworld.Greeter/SayHello

# HTTP endpoint  
curl -X POST http://localhost:8090/v1/example/echo -d '{"name": "World"}' -H "Content-Type: application/json"
```

## 📋 Available Commands

### Development
- `just install-deps` - Install required tools (buf, protoc plugins)
- `just dev` - Start development server locally
- `just dev-docker` - Start with Docker Compose
- `just proto` - Generate protobuf files
- `just build` - Build the server binary

### Testing & Quality
- `just test` - Run unit tests
- `just test-integration` - Run integration tests
- `just test-coverage` - Run tests with coverage report
- `just lint` - Run linter and format check
- `just format` - Format code

### Docker & Deployment
- `just docker-build` - Build Docker image
- `just docker-run` - Run container locally
- `just docker-push` - Push to registry

### Utilities
- `just clean` - Clean build artifacts
- `just docs` - Generate and serve API documentation
- `just health` - Check service health

## 🌐 API Documentation

### Endpoints

| Method | Path | Description |
|--------|------|-------------|
| `POST` | `/v1/example/echo` | Echo the input name |
| `GET` | `/health` | Health check endpoint |
| `GET` | `/metrics` | Prometheus metrics (if enabled) |
| `GET` | `/docs` | OpenAPI documentation |

### Example Requests

**Echo Request:**
```bash
curl -X POST http://localhost:8090/v1/example/echo \
  -H "Content-Type: application/json" \
  -d '{"name": "World"}'
```

**Response:**
```json
{
  "message": "Hello World"
}
```

**Health Check:**
```bash
curl http://localhost:8090/health
```

**Response:**
```json
{
  "status": "ok",
  "timestamp": "2025-08-13T19:30:00Z",
  "version": "1.0.0"
}
```

## 🐳 Docker Usage

### Development with Docker Compose
```bash
# Start all services
just dev-docker

# View logs
docker-compose logs -f

# Stop services
docker-compose down
```

### Production Docker Build
```bash
# Build optimized image
just docker-build

# Run container
just docker-run
```

## 🧪 Testing

```bash
# Run all tests
just test

# Run with coverage
just test-coverage

# Run integration tests
just test-integration

# Run specific test
go test -v ./internal/server -run TestServerHealth
```

## 🔧 Configuration

The service can be configured via environment variables:

| Variable | Default | Description |
|----------|---------|-------------|
| `SERVER_GRPC_PORT` | `8080` | gRPC server port |
| `SERVER_HTTP_PORT` | `8090` | HTTP gateway port |
| `LOG_LEVEL` | `info` | Logging level (debug, info, warn, error) |
| `LOG_FORMAT` | `json` | Log format (json, text) |
| `METRICS_ENABLED` | `true` | Enable Prometheus metrics |

Example `.env` file:
```bash
SERVER_GRPC_PORT=9090
SERVER_HTTP_PORT=8080
LOG_LEVEL=debug
LOG_FORMAT=text
```

## 🔄 Adding New Services

1. **Define the service in protobuf:**
```protobuf
service UserService {
  rpc CreateUser(CreateUserRequest) returns (CreateUserResponse) {
    option (google.api.http) = {
      post: "/v1/users"
      body: "*"
    };
  }
}
```

2. **Generate code:**
```bash
just proto
```

3. **Implement the service:**
```go
type UserService struct {
    helloworldpb.UnimplementedUserServiceServer
}

func (s *UserService) CreateUser(ctx context.Context, req *helloworldpb.CreateUserRequest) (*helloworldpb.CreateUserResponse, error) {
    // Implementation here
    return &helloworldpb.CreateUserResponse{}, nil
}
```

4. **Register in server:**
```go
helloworldpb.RegisterUserServiceServer(s, &UserService{})
helloworldpb.RegisterUserServiceHandler(ctx, gwmux, conn)
```

## 🚀 Deployment

### GitHub Actions

The template includes automated workflows:
- **CI**: Runs tests, linting, and security scans on PRs
- **CD**: Builds and pushes Docker images on releases
- **Dependency Updates**: Automated dependency updates

### Manual Deployment

```bash
# Build for production
just build

# Create Docker image
just docker-build

# Deploy to your platform
just docker-push
```

## 🤝 Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Run tests: `just test`
5. Submit a pull request


## 🔗 Useful Links

- [gRPC-Gateway Documentation](https://grpc-ecosystem.github.io/grpc-gateway/)
- [Protocol Buffers Guide](https://developers.google.com/protocol-buffers)
- [Buf Documentation](https://buf.build/docs/)
- [Go Standard Project Layout](https://github.com/golang-standards/project-layout)