1 May 2019 / #docker compose nginx config #docker nginx proxy

Docker Compose Nginx Tutorial

1. What is nginx?

Nginx is a reverse proxy, HTTP cache and load balancer. It aims to enhance performance by using less memory. Nginx is event-driven. That measns it uses one thread to receive requests, then it dispatch it to one or multiple threads asynchronously.

In this post, you will learn how to deploy a load balancer using nginx in docker.

2. Requirements

Docker
Docker compose

For this tutorial, you need a linux machine. I am using an Orange pi server because it is very performant and affordable.

Buy it from Aliexpress: Orange pi

3. How it works

Supposing you have 2 servers server1 and server2 that expose a web service. You want to dispatch the load on these 2 server. Using nginx, 50% of the requests will be handled by the server1 and 50% by server2. To do that you need to configure nginx.

request -------> nginx ----------> server1
                   |
                   |
                   |-------------> server2

4. Configuration

Nginx has a specific configuration syntax. You can check nginx official documentation for more details.

Create the configuration file nginx.conf.

events { worker_connections 1024; }

http {

    upstream app_servers {    # Create an upstream for the web servers
        server server1:80;    # the first server
        server server2:80;    # the second server
    }

    server {
        listen 80;

        location / {
            proxy_pass         http://app_servers;  # load balance the traffic
        }
    }
}

5. Preparing servers pages

We will create a minimal page for each server to test that load balancer works. To do that, create the file server1.html.

<html><body>server1</body></html>

Then, create the file server2.html:

<html><body>server2</body></html>

6. Docker compose file

Create the docker-compose.yml file in the same folder where you have create nginx.conf, server1.html and server2.html.

# docker-compose.yml file
version: '3'

services:
  # The load balancer
  nginx:
    image: nginx:1.16.0-alpine
    volumes:
      - ./nginx.conf:/etc/nginx/nginx.conf:ro
    ports:
      - "8080:80"

  # The web server1
  server1:
    image: nginx:1.16.0-alpine
    volumes:
      - ./server1.html:/usr/share/nginx/html/index.html

  # The web server2
  server2:
    image: nginx:1.16.0-alpine
    volumes:
      - ./server2.html:/usr/share/nginx/html/index.html

7. Test

Run the docker compose stack defined above with the command docker-compose up -d.

In your browser, go to http://localhost:8080 and refresh the page multiple times. You should see server1, then server2, then server1…

Congratulations, you have configured your nginx as a load balancer.