Go API Gateway 🚀

High-performance, lightweight API Gateway written in Go, featuring routing, rate limiting, observability, and resilience mechanisms.

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✨ Features

• Performance: Built with chi for fast, lightweight HTTP routing.
• Rate Limiting: Per-IP token-bucket rate limiting to prevent upstream overload.
• Resilience: Integrated Retry and Circuit Breaker patterns for proxying.
• Observability: Native Prometheus metrics and structured logging.
• Security: Request ID propagation and panic recovery middleware.
• Documentation: Built-in OpenAPI specification and Swagger UI.
• Modern: Fully containerized with Docker and Docker Compose.

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🛠 Tech Stack

• Language: Go 1.25
• Router: go-chi/chi
• Metrics: Prometheus
• Monitoring: Grafana
• Documentation: OpenAPI (Swagger)
• Containerization: Docker & Docker Compose

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🚀 Getting Started

Prerequisites

• Go 1.25+ (for local development)
• Docker & Docker Compose (for running the full stack)

Quick Start (Docker)

To launch the Gateway along with the Auth service, Prometheus, Grafana, and Swagger UI:

docker compose up --build

Local Development

1. Install dependencies:

   go mod download

2. Run the server:

   go run ./cmd/server

   Note: Ensure AUTH_SERVICE_URL is configured if testing proxying.

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⚙️ Configuration

The Gateway is configured using environment variables.

Variable	Description	Default
APP_PORT	Port for the gateway server	8080
APP_ENV	Environment (local, docker)	local
LOG_LEVEL	Logging level (debug, info, warn, error)	info
AUTH_SERVICE_URL	Upstream Auth service URL	http://localhost:8081
UPSTREAM_TIMEOUT_SECONDS	Proxy request timeout	5
RATE_LIMIT_RPS	Allowed requests per second per IP	10
RATE_LIMIT_BURST	Burst capacity per IP	20

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🛣 API Endpoints

Internal

• GET /health: Health check endpoint.
• GET /metrics: Prometheus metrics.
• GET /api/v1/ping: Simple connectivity test.
• GET /docs/*: Serves openapi.yaml.

Proxying (to Auth Service)

• ANY /api/v1/auth/*: Routed to Auth Service.
• ANY /api/v1/users/*: Routed to Auth Service.

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🛡 Resilience & Rate Limiting

• Rate Limiting: Rejects excessive traffic with 429 Too Many Requests and includes Retry-After header.
• Retries: Automatically retries failed requests to upstream services.
• Circuit Breaker: Monitors upstream health and "trips" if failures exceed thresholds, preventing cascading failures.

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📊 Monitoring & Docs

Service	URL	Credentials
Gateway	http://localhost:8080	-
Swagger UI	http://localhost:8082	-
Prometheus	http://localhost:9090	-
Grafana	http://localhost:3000	admin / admin

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📜 License

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