🚀 Redis Rate Limiter (Go)

A high-performance distributed rate limiter built using Go, Redis, and Lua scripting. Implements the Token Bucket algorithm with atomic operations for accurate and scalable request throttling.

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✨ Features

• ⚡ High-performance rate limiting using Go
• 🧠 Token Bucket algorithm (smooth + burst handling)
• 🔒 Atomic operations using Redis Lua scripts
• 🌐 Middleware-based integration (Gin)
• 📊 Rate limit headers (X-RateLimit-*)
• 🔄 Distributed & horizontally scalable
• 🧪 Load testing support
• ⚙️ Configurable via environment variables

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🏗️ Architecture

Client → API (Gin) → Rate Limiter Middleware → Redis (Lua)

• Redis stores token state
• Lua ensures atomic updates
• Middleware enforces limits before request reaches handler

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📁 Project Structure

rate-limiter-go/
│
├── cmd/server/main.go
├── internal/
│   ├── config/
│   ├── limiter/
│   ├── handlers/
│   ├── router/
│
├── scripts/loadtest.go
├── docker/docker-compose.yml
├── .env
├── README.md

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⚙️ Setup

1. Clone repository

git clone https://github.com/GauravKesh/rate-limiter
cd rate-limiter

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2. Setup environment variables

Create .env file:

PORT=3000
REDIS_HOST=localhost
REDIS_PORT=6379
RATE_LIMIT_CAPACITY=10
RATE_LIMIT_REFILL=1

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3. Start Redis

Using Docker:

docker run -p 6379:6379 redis

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4. Run server

go run cmd/server/main.go

Server will start at:

http://localhost:3000

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🧪 Load Testing

Run:

go run scripts/loadtest.go

Example output:

Total Requests: 200
Success (200): 10
Rate Limited (429): 190
Failed: 0

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📡 API Response Headers

Header	Description
X-RateLimit-Limit	Max requests allowed
X-RateLimit-Remaining	Remaining tokens

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🧠 Algorithm

Token Bucket

• Each user has a bucket with limited tokens
• Tokens refill over time
• Each request consumes a token
• If no tokens → request rejected (429)

Benefits:

• Smooth rate limiting
• Allows bursts
• More accurate than fixed window

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🔧 Configuration

Environment variables:

Variable	Description	Default
PORT	Server port	3000
REDIS_HOST	Redis host	localhost
REDIS_PORT	Redis port	6379
RATE_LIMIT_CAPACITY	Max tokens	10
RATE_LIMIT_REFILL	Tokens/sec	1

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🚀 Future Improvements

• 🔑 API key / user-based rate limiting
• 📊 Metrics (Prometheus + Grafana)
• 🌍 Redis Cluster support
• 🧱 Circuit breaker (Redis fallback)
• 🖥️ Admin dashboard (Next.js)
• ⚡ k6 benchmarking

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📜 License

MIT License