L7 Load Balancer Rate Limiter

A simple Layer 7 (Application Layer) load balancer implemented in Python using the Flask framework and multithreading. It also includes an IP-based rate limiting feature implemented using Redis.

Project Overview

This project aims to build a basic load balancer that distributes HTTP requests across multiple backend servers efficiently. The load balancer is designed to ensure high availability and reliability by dynamically routing traffic to healthy servers. It provides flexibility in handling server additions and removals based on demand.

Features

• Round Robin Load Balancing: Distributes incoming requests among multiple backend servers in a round-robin fashion.
• Multithreading: Utilizes Python's multithreading capabilities to handle concurrent connections efficiently.
• IP-Based Rate Limiting: To prevent abuse and ensure fair usage, the load balancer implements IP-based rate limiting. Each client IP address is allowed a certain number of requests per time period. If a client exceeds this limit, their requests are temporarily blocked until the next time period. This feature is implemented using Redis, a fast, in-memory data store.
• Health Checks: Periodically checks the health of backend servers using HTTP GET requests. Unhealthy servers are temporarily removed from the list.
• Dynamic Server Management: Allows adding or subtracting servers dynamically based on demand.

Getting Started

• Setup Redis: The IP-based rate limiting feature requires a running Redis server. If you don't have Redis installed, you can download it from the official website. Once you have Redis installed, you can start the server with the default configuration by running redis-server in your terminal.

• Setup Virtual Environment:

  python3 -m venv .venv
  source .venv/bin/activate

• Install Dependencies:

  python -m pip install --upgrade pip
  pip install -r requirements.txt

  • Run Backend Servers:

  python server.py

  python server.py --port 5001

  python server.py --port 5002

  • Run Load Balancer:

  python load_balancer.py

  • Test Load Balancer:

   curl http://127.0.0.1:8000

Testing

Unit Tests: Includes unit tests for load balancer functionality.

# test round robin load balancing, Make sure to run all 3 backend servers first
python test/round_robin.py

Contributing

Feel free to contribute by opening issues, suggesting improvements, or submitting pull requests. Your feedback is valuable!

License

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