Go Load Balancer Go!!

I genuinely believe that in order to understand a concept, you must try building it from scratch.

Here is a simple Golang implementation of a load balancer that was given as a homework exercise in The System Design Masterclass by Arpit Bhayani.

Install dependencies

TODO

[Optional] Update config.json

You can customize the load balancer's behavior by modifying config.json. The following options are available:

port: Specifies the port on which the load balancer runs locally. You can change it as needed.

healthCheckInterval: Defines the interval (in milliseconds) at which the load balancer continuously polls all registered servers to check their health.

lbAlgo: Determines the load-balancing strategy. Available options:

• round-robin
• random
• least-connections

servers: Lists the backend servers that the load balancer can route traffic to.

maxRetries: Specifies the number of retry attempts when a server fails to process a request. The request is forwarded to the next available server based on the selected load-balancing strategy.

Run the load balancer

# 1. Clone this repo
git clone https://github.com/thedatamonk/go-load-balancer.git

# 2. Go to the main directory
cd go-load-balancer

# 3. Start the HTTP servers
# This will also use config.json as input to get the name of the servers that need to be managed by the load balancer
python manage_servers.py

# 4. Start the load balancer
# The load balancer will be started on the localhost at the port number specified in the config.json
go run .

# 5. Send a request to the load balancer
# The grep command is used for extracting the value of "X-Forwarded-Server" from the server response.
curl -s -i http://localhost:8080 | grep "X-Forwarded-Server"

How to Perform Load Testing

You can use Artillery to simulate high traffic and measure the performance of your load balancer.

Prerequisites

Ensure you have Artillery installed. If not, install it globally using:

npm install -g artillery@latest

Running the Load Test

Execute the following command to run a load test using artillery.yaml:

artillery run artillery.yaml --record --key ARTILLERY_API_KEY

Why This Might Be Helpful for You

• Use this as a base project to implement your own load balancer.
• Experiment with different load balancer settings to observe their impact.
• Gain a deeper understanding of how a load balancer works by interacting with its configurations and mechanisms.

Features

1. Dynamic Server Scaling

   • Add new servers dynamically via an API endpoint to handle increased traffic.

2. Automatic Removal of Unhealthy Servers

   • Servers are monitored continuously.
   • If a server fails to respond for a specified threshold duration, it is automatically removed from the pool.

3. Intelligent Retry Mechanism

   • If a server fails to process a request, the load balancer retries the request with another available server.

4. Multiple Load Balancing Strategies

   • Supports the following strategies:
     • Round Robin
     • Random
     • Least Connections