Load Balancer

A simple HTTP load balancer built with Node.js and Express. It distributes incoming requests to multiple backend servers using a round-robin algorithm and performs periodic health checks to ensure requests are only sent to healthy servers.

Features

• Round-robin load balancing across multiple backend servers
• Health checks for backend servers (via /health endpoint)
• Automatic failover: unhealthy servers are skipped until healthy again
• Detailed logging of incoming requests and backend responses
• Handles all HTTP methods and paths
• Graceful shutdown on SIGINT

Getting Started

Prerequisites

• Node.js (v16 or newer recommended)
• npm

Installation

1. Clone the repository:

   git clone https://github.com/mohanad-80/load-balancer.git
   cd load-balancer

2. Install dependencies:

   npm install

Running Backend Servers

Start multiple backend servers on different ports (e.g., 3001, 3002, 3003):

PORT=3001 node be.js
PORT=3002 node be.js
PORT=3003 node be.js

You can use multiple terminals or a process manager like pm2.

Running the Load Balancer

Start the load balancer (listens on port 3000 by default):

node lb.js

Usage

Send HTTP requests to the load balancer:

curl http://localhost:3000/

Requests will be forwarded to healthy backend servers in round-robin order.

Project Structure

• lb.js - Main load balancer logic
• be.js - Simple backend server for testing
• package.json - Project metadata and dependencies

Customization

• Edit the servers array in lb.js to add or remove backend servers.
• Adjust health check interval or timeout as needed.

License

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

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Author: Mohanad Ahmed