Go GraphQL Example

A production-ready GraphQL service built in Go, demonstrating Clean Architecture principles with Domain-Driven Design (DDD) patterns. This project serves as both a functional GraphQL API and an educational reference for building scalable web services.

🚀 Features

• GraphQL API: Schema-first GraphQL implementation with gqlgen
• Clean Architecture: Clear separation of concerns across domain, application, infrastructure, and interface layers
• User Management: Complete CRUD operations with pagination support
• Database Integration: PostgreSQL with migrations and connection pooling
• Docker Support: Multi-stage builds with development and production configurations
• Configuration Management: Environment-based configuration with validation
• Structured Logging: JSON-formatted logging with configurable levels
• Health Checks: Built-in health monitoring and startup validation
• Testing: Comprehensive unit and integration tests with mocking
• Development Tools: Makefile automation and Docker Compose setup

📋 Table of Contents

• Quick Start
• Architecture
• API Documentation
• Development
• Docker Deployment
• Testing
• Configuration
• Contributing
• License

🏃 Quick Start

Prerequisites

• Go 1.24.3 or later
• PostgreSQL 12+ (or use Docker Compose)
• Make (optional, for convenience commands)

Using Docker Compose (Recommended)

1. Clone the repository

   git clone https://github.com/captain-corgi/go-graphql-example.git
   cd go-graphql-example

2. Start all services

   make docker-run
   # or manually: docker-compose up -d

3. Access the GraphQL Playground

   make playground
   # or visit: http://localhost:8080/playground

Local Development Setup

1. Install dependencies

   make setup

2. Start PostgreSQL (if not using Docker)

   # Using Docker for database only
   docker run --name postgres -e POSTGRES_PASSWORD=postgres -e POSTGRES_DB=graphql_service -p 5432:5432 -d postgres:16-alpine

3. Run migrations

   make migrate-up

4. Start the development server

   make dev

🏗 Architecture

This project implements Clean Architecture with the following layers:

┌─────────────────────────────────────────────────────────────┐
│                    Interfaces Layer                         │
│  ┌─────────────────┐  ┌─────────────────┐                  │
│  │  GraphQL        │  │  HTTP Server    │                  │
│  │  Resolvers      │  │  & Middleware   │                  │
│  └─────────────────┘  └─────────────────┘                  │
└─────────────────────────────────────────────────────────────┘
                              │
┌─────────────────────────────────────────────────────────────┐
│                   Application Layer                         │
│  ┌─────────────────┐  ┌─────────────────┐                  │
│  │  Use Cases      │  │  DTOs &         │                  │
│  │  & Services     │  │  Orchestration  │                  │
│  └─────────────────┘  └─────────────────┘                  │
└─────────────────────────────────────────────────────────────┘
                              │
┌─────────────────────────────────────────────────────────────┐
│                     Domain Layer                            │
│  ┌─────────────────┐  ┌─────────────────┐                  │
│  │  Entities &     │  │  Repository     │                  │
│  │  Value Objects  │  │  Interfaces     │                  │
│  └─────────────────┘  └─────────────────┘                  │
└─────────────────────────────────────────────────────────────┘
                              │
┌─────────────────────────────────────────────────────────────┐
│                 Infrastructure Layer                        │
│  ┌─────────────────┐  ┌─────────────────┐                  │
│  │  Database       │  │  Configuration  │                  │
│  │  Repositories   │  │  & Logging      │                  │
│  └─────────────────┘  └─────────────────┘                  │
└─────────────────────────────────────────────────────────────┘

Key Principles

• Dependency Inversion: Inner layers define interfaces, outer layers implement them
• Framework Independence: Business logic is isolated from frameworks
• Testability: Easy mocking and testing through dependency injection
• Single Responsibility: Each layer has a clear, focused purpose

📚 API Documentation

GraphQL Endpoint

• URL: http://localhost:8080/query
• Playground: http://localhost:8080/playground
• Health Check: http://localhost:8080/health

Example Queries

Get a user by ID:

query GetUser {
  user(id: "550e8400-e29b-41d4-a716-446655440001") {
    id
    email
    name
    createdAt
    updatedAt
  }
}

List users with pagination:

query GetUsers {
  users(first: 10) {
    edges {
      node {
        id
        email
        name
      }
      cursor
    }
    pageInfo {
      hasNextPage
      endCursor
    }
  }
}

Create a new user:

mutation CreateUser {
  createUser(input: {
    email: "[email protected]"
    name: "John Doe"
  }) {
    user {
      id
      email
      name
    }
    errors {
      message
      field
    }
  }
}

For more examples, see the examples/graphql/ directory.

🛠 Development

Available Make Commands

# Development
make dev              # Run with development config
make run              # Run the application
make build            # Build binary
make clean            # Clean build artifacts

# Code Generation
make generate         # Generate all code (GraphQL + mocks)
make generate-graphql # Generate GraphQL code only
make generate-mocks   # Generate mocks only

# Testing
make test             # Run all tests
make test-integration # Run integration tests
make coverage         # Generate coverage report

# Database
make migrate-up       # Run migrations
make migrate-down     # Rollback migrations
make migrate-create NAME=migration_name  # Create new migration

# Docker
make docker-run       # Start with Docker Compose
make docker-stop      # Stop Docker services
make docker-clean     # Clean Docker resources

# Code Quality
make lint             # Run linters
make format           # Format code
make check            # Run all checks

# Utilities
make setup            # Setup development environment
make playground       # Open GraphQL Playground

Project Structure

├── api/graphql/              # GraphQL schema files
├── cmd/server/               # Application entry point
├── internal/
│   ├── application/          # Use cases and services
│   ├── domain/               # Core business logic
│   ├── infrastructure/       # External adapters
│   └── interfaces/           # Delivery layer
├── migrations/               # Database migrations
├── configs/                  # Configuration files
├── examples/                 # API usage examples
├── docs/                     # Documentation
└── scripts/                  # Utility scripts

Adding New Features

1. Define GraphQL Schema: Add types to api/graphql/*.graphqls
2. Generate Code: Run make generate-graphql
3. Implement Domain Logic: Add entities and repositories in internal/domain/
4. Create Use Cases: Add services in internal/application/
5. Implement Resolvers: Update resolvers in internal/interfaces/graphql/resolver/
6. Add Tests: Write unit and integration tests
7. Update Documentation: Update relevant docs

🐳 Docker Deployment

Development

# Start all services (includes database)
docker-compose up -d

# View logs
docker-compose logs -f

# Stop services
docker-compose down

Production

# Build and start production services
make docker-prod-build

# Or manually
docker-compose -f docker-compose.yml -f docker-compose.prod.yml up -d --build

Environment Variables for Production

# Required for production
export POSTGRES_PASSWORD=your_secure_password
export DATABASE_URL=postgres://user:pass@host:5432/dbname?sslmode=require

# Optional
export POSTGRES_DB=graphql_service
export POSTGRES_USER=postgres

🧪 Testing

Running Tests

# All tests
make test

# With coverage
make coverage

# Integration tests only
make test-integration

# Specific package
go test ./internal/domain/user/...

Test Structure

• Unit Tests: Test individual components in isolation
• Integration Tests: Test component interactions with real database
• Mocks: Generated mocks for all interfaces using gomock

Writing Tests

//go:generate go run github.com/golang/mock/mockgen -source=$GOFILE -destination=./mocks/mock_$GOFILE -package=mocks

// Add this directive to interface files for automatic mock generation

⚙️ Configuration

Configuration is managed through YAML files with environment variable overrides:

Configuration Files

• configs/config.yaml - Base configuration
• configs/config.development.yaml - Development overrides
• configs/config.docker.yaml - Docker environment
• configs/config.production.yaml - Production settings

Environment Variables

# Application
CONFIG_FILE=path/to/config.yaml
GIN_MODE=release

# Database
DATABASE_URL=postgres://user:pass@host:5432/dbname

# Logging
LOG_LEVEL=info
LOG_FORMAT=json

🤝 Contributing

We welcome contributions! Please see our Contributing Guide for details.

Development Workflow

1. Fork the repository
2. Create a feature branch: git checkout -b feature/amazing-feature
3. Make your changes following our coding standards
4. Add tests for new functionality
5. Run the test suite: make check
6. Commit your changes: git commit -m 'Add amazing feature'
7. Push to the branch: git push origin feature/amazing-feature
8. Open a Pull Request

Code Standards

• Follow Go conventions and idioms
• Maintain Clean Architecture boundaries
• Write comprehensive tests
• Update documentation for new features
• Use conventional commit messages

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

• gqlgen for GraphQL code generation
• Gin for the HTTP framework
• Clean Architecture by Robert C. Martin
• Domain-Driven Design by Eric Evans

📞 Support

• 📖 Documentation
• 🐛 Issue Tracker
• 💬 Discussions

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Happy coding! 🚀