go-load-balancer

README

Go load balancer

Creating a full-featured load balancer in Go that can distribute HTTP requests to multiple backend servers using weighted round-robin algorithm, Circuit Breaker and other. This project uses only Go standard library.

Features

• Server Pool: Maintains a list of backend servers.
• Weighted Round-Robin Algorithm: Selects servers based on dynamically adjusted weights.
• Health Checks: Periodically checks the health of each server and updates their status.
• Circuit Breaker: Protects failing servers from being overloaded by temporarily removing them from the selection pool.
• Dynamic Weight Adjustment: Adjusts server weights based on performance, including response time and failure count.

Project Structure

• main.go: Entry point for the load balancer server.
• load-balancer/main.go: Contains the core load balancer logic.
• logger/main.go: Custom logger implementation for consistent logging throughout the application.
• server*/ : Backend servers

Getting Started

Prerequisites

• Go 1.23.0 (1.20+)
• A set of backend servers to balance. For this example, servers are expected to be running on http://localhost:8081, http://localhost:8082, and http://localhost:8083 (You can add more servers depending on what your need).

Installation

1. Clone the repository:

git clone https://github.com/Kei-K23/go-load-balancer
cd go-load-balancer

1. Run the Load Balancer:

go run main.go

1. Run backend servers

# navigate to the server folder
cd server1
# run Go file
go run main.go
# You can run backend servers as you need

1. Stop the Load Balancer:

Press Ctrl+C in the terminal or send a termination signal to gracefully shut down the load balancer.

Adding Backend servers

I write ready to use shell script to generate Go backend servers in the project root path. All you need to do is adding the backend server address to main entry point for load balancer.

1. Run add server shell script in the root terminal to create new server

# Make sure server name should be in the format of name+number e.g(server5, server6 up to server9)
./add_server.sh server4

1. Add newly added server address to load balancer

// /main.go

// This is predefine backend servers
serverPool.AddServer(loadbalancer.NewServer("http://localhost:8081"))
serverPool.AddServer(loadbalancer.NewServer("http://localhost:8082"))
serverPool.AddServer(loadbalancer.NewServer("http://localhost:8083"))
// e.g. serverPool.AddServer(loadbalancer.NewServer("http://localhost:8084"))
// add more backend servers here

Testing the load balancer and backend servers

To perform load-testing, you can use any load-testing tool that you want. In my case, I use JMeter and prepare the test plan.

# Run this command in the root terminal
jmeter -n -t /Your-Path/go-load-balancer/load-testing.jmx -l /Your-Path/go-load-balancer/results.jtl -Jproperty_name=value

# e.g for my case jmeter -n -t /Users/user/Desktop/projects/go-projects/go-load-balancer/load-testing.jmx -l /Users/user/Desktop/projects/go-projects/go-load-balancer/results.jtl -Jproperty_name=value

Todo

• Publish load-balancer as Go package. (I will publish as package only when the code meet the requirement as actual real-world load balancer)
• Add request filtering and banning (To be as like API Gateway but API Gateway and Load balancer are different topic)
• Add failure recovery
• Add testing
• Add more features, improve performance

Contributing

Contributions are welcome! Please fork the repository and open a pull request with your changes.

License

This project is licensed under the Apache-2.0 License. See the LICENSE file for details.