Load Balancing with Nginx

Trying out nginx as a load balancer, using default Weighted Round Robin algorithm.

Idea

We have created an express app. The app code is really simple, and you can find the code in the server/ directory.

The app has only one endpoint, /hello, which returns a JSON response like

{
  "message": "Hello World!!",
  "serverId": "34035283-4089-4345-ba4c-0e4afc0392fb"
}

The message property is always the same, however the serverId property will keep changing as you refresh the page.

With the docker-componse.yml configuration, we have spawned up three express servers, and every server has one unique server id. The serverId represents the unique server id.

Note: If you restart the servers, the id will change

Nginx configuration

We have a custom(and very simple) nginx configuration in nginx/conf/nginx.conf file.

This part is important

upstream upstream-server {
    server server1:3000 weight=5;
    server server2:3001 weight=4;
    server server3:3002 weight=3;
}

server1, server2 and server3 are the three express servers that we start and route requests to them according on their weights.

Read more on this algorithm: https://www.nginx.com/resources/glossary/round-robin-load-balancing/

How to run

Make sure you have docker and docker-compose installed.

Clone the repository

git clone https://github.com/goldenrati0/nginx-load-balancing-example.git

Navigate to the directory

cd nginx-load-balancing-example/

Run with docker-compose

docker-compose up

This should be enough. It will pull/build docker images and will start the nginx server in port 80.

Browse http://127.0.0.1/hello