Order Service

A high-performance, production-ready Go microservice for handling orders. It consumes order data from Kafka, stores it in PostgreSQL with transactional integrity, caches it in-memory for fast retrieval, and serves it via a REST API and a modern Web UI.

🚀 Features

• Event-Driven Architecture: Consumes orders from Kafka asynchronously.
• Robust Storage: Uses PostgreSQL with GORM.
  • Transactional Integrity: Ensures atomicity when saving orders and items.
  • Connection Retries: Resilient startup logic for database connections.
• High Performance:
  • In-Memory Caching: Implements go-cache with TTL and automatic cleanup to prevent memory leaks.
• Reliability:
  • Graceful Shutdown: Handles SIGTERM/SIGINT to ensure in-flight requests and database operations complete safely.
  • Input Validation: Uses validator/v10 to ensure data integrity before processing.
• Quality Assurance:
  • Unit & Integration Tests: Comprehensive test coverage.
  • Linting: strictly follows Go standards.
• User Interface: Modern, responsive Web UI to view order details.

🛠 Tech Stack

• Language: Go 1.25+
• Database: PostgreSQL 15
• Message Broker: Apache Kafka + Zookeeper
• Libraries:
  • gorilla/mux: HTTP Routing
  • gorm: ORM & Database Management
  • sarama: Kafka Client
  • go-cache: In-memory Caching
  • validator: Struct Validation
  • gofakeit: Realistic Data Generation (for testing)

📂 Project Structure

├── cmd/
│   ├── server/       # Main application entry point
│   └── producer/     # Data generator for Kafka
├── internal/
│   ├── cache/        # In-memory caching layer
│   ├── config/       # Configuration management
│   ├── handlers/     # HTTP handlers
│   ├── kafka/        # Kafka consumer logic
│   └── repository/   # Database access layer
├── migrations/       # SQL migration files
├── web/              # Static frontend assets
├── tests/            # Integration tests
├── docker-compose.yml # Infrastructure (DB, Kafka, Zookeeper)
└── Makefile          # Build and run commands

🏁 Getting Started

Prerequisites

• Go 1.25+
• Docker & Docker Compose
• Make (optional, for convenience)

1. Start Infrastructure

Start PostgreSQL, Kafka, and Zookeeper using Docker Compose:

docker-compose up -d

2. Configure Environment

The service uses default configuration suitable for local development. You can customize it via .env file if needed (see .env.example).

3. Run the Service

Start the main API server and Kafka consumer:

make run

The server will start on port 8080.

4. Generate Data

Simulate incoming orders by running the producer script:

make producer

This sends random JSON order data to the Kafka topic.

5. Access Web UI

Open your browser and navigate to:

http://localhost:8080

Enter an Order ID (e.g., from the producer output) to view its details.

🧪 Testing

Run all unit and integration tests:

make test

🧹 Linting

Run linters to ensure code quality:

make lint

📜 API Endpoints

Method	Endpoint	Description
GET	/	Serve Web UI
GET	/order/{id}	Get Order JSON by ID

🤝 Contribution

1. Fork the repository
2. Create your feature branch (git checkout -b feat/amazing-feature)
3. Commit your changes (git commit -m 'feat: add amazing feature')
4. Push to the branch (git push origin feat/amazing-feature)
5. Open a Pull Request

📄 License

Distributed under the MIT License.