L4 Load Balancer

A high-performance Layer 4 (TCP) load balancer implemented in Go.

Features

• Multiple Load Balancing Algorithms

  • Round Robin
  • Least Connections (TODO)

• Health Checking

  • Automatic backend health monitoring
  • Configurable check intervals
  • Unhealthy backend removal

• Connection Pooling

  • Efficient connection reuse
  • Configurable pool sizes
  • Connection lifecycle management

• Configuration Management

  • YAML-based configuration
  • Runtime configuration reloading (TODO)

Project Structure

├── cmd/
│   └── main.go                 # Application entry point
├── internal/
│   ├── balancer/
│   │   ├── balancer.go         # Core load balancer logic
│   │   └── algorithms.go       # Load balancing algorithms
│   ├── backend/
│   │   └── backend.go          # Backend server management
│   ├── health/
│   │   └── checker.go          # Health checking functionality
│   └── config/
│       └── config.go           # Configuration management
├── pkg/
│   └── pool/
│       └── pool.go             # Connection pooling
├── configs/
│   └── config.yaml             # Sample configuration
├── go.mod
├── go.sum
└── README.md

Configuration

The load balancer is configured using a YAML file. See configs/config.yaml for an example.

Configuration Options

• loadbalancer.listen_address: Address to listen on (e.g., ":8080")
• loadbalancer.algorithm: Load balancing algorithm ("round_robin", "least_connections")
• backends: List of backend servers with address and port
• healthcheck.interval: How often to check backend health
• healthcheck.timeout: Timeout for health checks

Usage

1. Build the application:

   go build -o l4-load-balancer ./cmd

2. Run with default configuration:

   ./l4-load-balancer

3. Run with custom configuration:

   ./l4-load-balancer -config configs/config.yaml

Development

Prerequisites

• Go 1.19 or later

Running Tests

go test ./...

Adding New Load Balancing Algorithms

1. Implement the Algorithm interface in internal/balancer/algorithms.go
2. Add the algorithm to the algorithm factory/registry
3. Update configuration options

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests
5. Submit a pull request

License

MIT License (add your license details)

TODO

• Implement least connections algorithm
• Add weighted round robin
• Add SSL/TLS termination
• Add metrics and monitoring
• Add graceful shutdown
• Add configuration hot-reloading
• Add rate limiting
• Add connection limiting per backend
• Add logging configuration
• Add Docker support