🚦 Rate Limiter

This Rate Limiter is a lightweight, API rate limiting service built with FastAPI and Redis. It enables developers to define custom rate-limiting policies per route and user role, with secure API-key-based access and real-time enforcement.

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✨ Features

• 🔐 API Key Authentication – Secure all operations with unique API keys
• 📊 Policy-Based Limiting – Define per-route and per-role rate limits
• 🧠 Multi-Tenant Support – Isolate usage per registered client
• 📄 Structured Logging – Store the last 1000 requests per client in Redis
• 🛡️ IP Rate Limiting on Internal Routes – Prevent abuse of sensitive endpoints
• 📚 Interactive API Docs – Swagger UI at /docs out of the box

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🛠️ Tech Stack

• FastAPI – for building high-performance REST APIs
• Redis – used as the backend for rate limiting and logging
• Pydantic – for request/response validation
• Python 3.11+

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📦 Endpoints Overview

Method	Path	Description	Auth Required
POST	/register	Register a new app and get an API key	❌ No
POST	/policy	Define a rate limiting policy	✅ Yes
GET	/policy	Fetch existing policies	✅ Yes
DELETE	/policy	Remove a policy	✅ Yes
POST	/check	Check if a request is allowed	✅ Yes
GET	/logs/latest	Fetch recent rate limit logs	✅ Yes
GET	/docs	Interactive API documentation	❌ No

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🚀 Quick Start (Local)

1. Clone the Repository

git clone https://github.com/prabhat328/rate_limiter.git
cd rate_limiter

2. Install Dependencies

python -m venv env
source env/bin/activate  # On Windows use `env\Scripts\activate`
pip install -r requirements.txt

3. Start Redis (Docker or local install)

docker run -d -p 6379:6379 --name redis redis:7

The app uses the following environment variables for Redis configuration:

• REDIS_HOST (default: localhost)
• REDIS_PORT (default: 6379)

You can optionally define a .env file in the root for any other configuration:

REDIS_HOST=localhost
REDIS_PORT=6379

4. Run the App

uvicorn main:app --reload

Visit: http://localhost:8000/docs

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🔐 Example Usage

Register a New App

curl -X POST http://localhost:8000/register -H "Content-Type: application/json" -d '{"name": "my-app"}'

Define a Policy

curl -X POST http://localhost:8000/policy \
  -H "Content-Type: application/json" \
  -H "X-API-Key: YOUR_API_KEY" \
  -d '{
        "route_key": "get_users",
        "limit": 10,
        "window_seconds": 60,
        "role": "basic"
      }'

Check a Request

curl -X POST http://localhost:8000/check \
  -H "Content-Type: application/json" \
  -H "X-API-Key: YOUR_API_KEY" \
  -d '{
        "user_id": "user_123",
        "route_key": "get_users",
        "role": "basic"
      }'

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📂 Project Structure

app/
├── api/                 # API route definitions
├── core/                # Core logic (rate limiter, auth, policy, logging)
├── models/              # Pydantic request and response models
redis.py                 # Redis client setup
config.py                # Centralized configuration loader (e.g., environment variables, settings)
main.py                  # FastAPI app entry point
requirements.txt

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🧠 Future Enhancements

• Support for advanced rate-limiting strategies like sliding window and token bucket algorithms
• Real-time log streaming via SSE for live request monitoring
• Integration with PostgreSQL for persistent storage of user policies and audit trails
• Development of a usage analytics dashboard to visualize request patterns and blocked events

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