Rust TCP Load Balancer

A lightweight, asynchronous TCP load balancer written in Rust using the Tokio runtime. This project distributes incoming TCP connections across multiple backend servers using round-robin selection, with real-time health checks to ensure traffic is only sent to healthy servers.

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Features

• Round-Robin Load Balancing: Evenly distributes incoming connections across available servers
• Real-Time Health Checks: Continuously verifies server availability before forwarding traffic
• Shared State Management: Uses Arc<Mutex<>> for safe, concurrent access to server state
• Graceful Shutdown: Supports clean termination with Ctrl+C
• Configurable Health Check Interval: Adjustable health check timing via CLI argument

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Quick Start

Requirements

• Rust (stable)
• Cargo

Run the Load Balancer

cargo run -- --client 127.0.0.1:8000 --server 127.0.0.1:9001 --server 127.0.0.1:9002

This starts the load balancer on port 8000 and distributes connections across the backend servers on ports 9001 and 9002.

Optional: Set Health Check Interval

cargo run -- --client 127.0.0.1:8000 --server 127.0.0.1:9001 --interval 10

This configures the health check interval to 10 seconds.

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How It Works

• The load balancer listens for incoming TCP connections on the client port
• Backend servers are tracked with health status updated via periodic TCP connection checks
• Only healthy servers receive traffic
• Connections are forwarded using a round-robin algorithm, ensuring even distribution
• A background task continuously monitors server health
• Supports clean shutdown with Ctrl+C

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📁 Project Structure

• main.rs: Core application logic, argument parsing, health checks, and proxy forwarding
• ServerEntry: Tracks each backend server's address and health status
• Uses tokio for async networking and clap for command-line argument parsing

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Future Enhancements

Potential next steps:

• Weighted load balancing based on server capacity
• Prometheus-style metrics endpoint
• Configurable connection limits per backend
• Support for additional balancing algorithms (least-connections, random selection)

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