go-loadbalancer

A load balancer supporting multiple load balancing strategies

Load Balancing Algorithms

• Round Robin
• Weighted Round Robin

Round Robin

Round Robin is a simple load balancing algorithm that involves distributes network traffic to different app servers (replicas) in a sequential order with no preference (one after the other).

Weighted Round Robin

Weighted Round Robin is a variant of Round Robin that takes into consideration the possibility of the different app servers having different computing capacity. The capacity of each app server is specified using weights. A weight is simply the relative ratio of the computing capacity of each app server.

Features

• Easy configuration of services and its replicas using yaml
• Health checks for each app replica
• Path forwarding for each service
• Forwarding to replicas through reverse proxies
• Hot Reloading for config files

Setup

• Clone repository using

git clone https://github.com/Emmrys-Jay/go-loadbalancer.git

• Create a config yaml file in the root directory. Sample:

# Sample config yaml
strategy: "RoundRobin"
services: 
  - name: "Service01"
    matcher: "/api/v1"
    strategy: "RoundRobin"
    replicas: 
    - url: "http://localhost:8081"
    - url: "http://localhost:8082"

Yaml Field	Description
strategy	The default load balancing algorithm for all services
services	An array of services made up of the name matcher, strategy and replicas
matcher	A string in the format of a url path that matches a network request to the load balancer to a service
strategy	The load balancing algorithm for a particular service.
replicas	An array which contains the address of each instance of the server in the form <host>:<port>.
url	The url of each server replica in the form <host>:<port>.
weight	Used in WeightedRoundRobin strategy to signify the weights of each server replica.

• Run the project using the command below. The default port is 8080.

go run cmd/server/main.go --port /port/to/start/the/lb/server --config /path/to/your/config/file

• To test the program without going through the process of creating your own config files, run the program using the default config file for a RoundRobin strategy in example/config.yaml using:

go run cmd/server/main.go --port /port/to/start/the/lb/server

• Forward requests to the load balancer using curl or via the browser. Ensure the path in your load balancer url indicates the matcher for the service you want to visit. For example, sending requests to the load balancer for the service in the example RoundRobin config file above will be:

curl localhost:8080/api/v1

• You can view a sample of a WeightedRoundRobin config file in example/config-weighted.yaml

Building a demo

If you want to try load balancer, you can run the demo server in the cmd/demo/main.go directory, which starts up a hello world server listening to a specified port.

Launching a demo server is as easy as:

go run cmd/demo/main.go --port /port/to/start/the/lb/server

NB: You are free to fork and use this project.