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Hermes Load Balancer

Welcome to Hermes, a robust HTTP load balancer and reverse proxy written from scratch in Go. Hermes is designed to optimize your network's load distribution, ensuring smooth and reliable service delivery.

⭐ Key Features

  • HTTP load balancing and reverse proxy functionality
  • Multiple load distribution strategies
  • Active and passive health checks for backend services
  • Easy configuration via YAML file or command-line arguments
  • Docker support for simple deployment

⚡ Load Distribution Strategies

Hermes supports multiple strategies to cater to different needs and infrastructure setups:

  • Round Robin: A fair and equal distribution method, perfect for when all backend services have similar processing capabilities.
  • Weighted Round Robin: Tailor the load distribution based on the processing power of each backend, assigning more weight to stronger servers.
  • Least Connections: Smartly routes traffic to the servers with the fewest active connections, minimizing response times and maximizing efficiency.

❤️ Health Checks

Hermes ensures high availability through two types of health checks:

  • Active Checks: During request processing, if a selected backend is unresponsive, it's immediately marked as down.
  • Passive Checks: Regular pings are sent to backends at fixed intervals to monitor their status.

🚀 Getting Started

Running Hermes is straightforward, with options for configuration file, command-line arguments, or Docker deployment.

Using a Configuration File

Ensure you have a config.yaml set up with your desired settings.

./hermes

Using Command-Line Arguments

./hermes --help

🐳 Running with Docker Compose

docker compose up

Hermes comes with Docker configurations for seamless deployment across any setup. To customize Hermes' deployment, modify the docker-compose.yaml file with your preferred settings.

⚙️ Configuration

Hermes can be configured using a YAML file. Here's an explanation of the configuration options:

port: 80 # Port on which the load balancer will be running
healthCheckInSec: 20 # Interval for passive health checks in seconds
strategy: "least-connections" # Load balancing strategy
services: # Backend services configuration
  - name: srv1
    url: http://localhost:9001
    weight: 30
  - name: srv2
    url: http://localhost:9002
    weight: 1
  - name: srv3
    url: http://localhost:9003
    weight: 1

Configuration Options

  • port: The port on which Hermes will listen for incoming requests.
  • healthCheckInSec: The interval (in seconds) for passive health checks.
  • strategy: The load balancing strategy. Possible values are "round-robin", "weighted-round-robin", or "least-connections".
  • services: A list of backend services.
    • name: A unique identifier for the service.
    • url: The URL of the backend service.
    • weight: The weight assigned to the service (required for "weighted-round-robin" strategy).

✨ Why Hermes?

  • Efficiency: Optimized for minimal latency and maximum throughput.
  • Flexibility: Supports multiple load distribution strategies.
  • Reliability: Active and passive health checks ensure high availability.
  • Ease of Use: Simple setup with Docker support for hassle-free deployment.

🚧 TODO

  • Implement a heap for sorting alive backends to reduce search complexity

👏 Acknowledgements

This project stands on the shoulders of giants. A heartfelt thank you to the following resources and communities:

Let's Create a Simple Load Balancer With Go - This insightful blog post was the spark that ignited the creation of Hermes. It provided foundational knowledge and inspiration.

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

📝 License

This project is licensed under the MIT License.