Load Balancer with Rate Limiting, Circuit Breaker, and Prometheus Metrics

Disclaimer: this project is a work in progress. I will be updating the readme as new features will be implemented.

This project implements a load balancer in Go with the following features:

• Request timeouts for backend servers
• Rate limiting using a token bucket algorithm
• Circuit breaker pattern for backend servers
• Prometheus metrics for monitoring

Project Structure

• main.go: Contains the main function and initializes the load balancer.
• load_balancer.go: Contains the LoadBalancer struct and its methods.
• rate_limiter.go: Contains the RateLimiter struct and its methods.
• circuit_breaker.go: Contains the CircuitBreaker struct and its methods.
• logging.go: Contains the logging function.
• metrics.go: Contains the Prometheus metrics definitions and registration.

Getting Started

Prerequisites

• Go 1.16 or later
• Prometheus

Installing

1. Clone the repository:

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

2. Install dependencies:

   go mod tidy

Running the Load Balancer

1. Start the backend servers (e.g., on ports 8081, 8082, 8083).

go run backend/main.go 8081
go run backend/main.go 8082
go run backend/main.go 8083

2. Run the load balancer:

   go run lb/main.go

3. The load balancer will start on port 8080.

Prometheus Metrics

• The metrics are exposed at /metrics endpoint.
• Configure Prometheus to scrape the metrics from the load balancer.

Features

Request Timeouts

The load balancer uses a custom http.Transport with timeouts for dialing and TLS handshake.

Rate Limiting

The RateLimiter struct implements a token bucket algorithm to limit the rate of incoming requests.

Circuit Breaker

The CircuitBreaker struct manages the state of each backend server (closed, open, half-open) to prevent sending requests to unhealthy servers.

Prometheus Metrics

The load balancer tracks the total number of requests and the duration of each request using Prometheus metrics.