Running Multiple Docker Containers on a Single Linux Webserver Server

Question

Hello I am currently planning out some server architecture with Docker. (I'm fairly new to Docker)

My goals are:

To have multiple docker containers running on a single ubuntu machine.
Each container uses the same ports for each process: (e.g.) localhost:8080 for frontend, localhost:3000 for backend.

How each container works:

Right now I'm using docker compose to run both frontend and backend.

docker-compose.yml

version: '3'
services:
  frontend:
    build: ./frontend
    ports:
      - 8080:80
    networks:
      - app-network
  backend:
    build: ./backend
    ports:
      - 3000:3000
    working_dir: /usr/src/server
    command: node server.bundle.js
    networks:
      - app-network
networks:
  app-network:
    driver: bridge

This works fine. I can visit localhost:8080 for webpage and localhost:3000 for backend.

Note: Front end container uses NGINX docker image, and backend uses NODE:10 docker image.

What I want to accomplish

On my server I will have another instance of NGINX. I would like to somehow containerize each docker-compose setup under one port like localhost:5000.

This way when I get a request from www.example-website1.com it redirects to localhost:5000, which then loads localhost:8080 from that docker-compose setup.

Again when I get a request from www.example-website2.com it redirects to localhost:5001, which then loads localhost:8080 from another docker-compose setup.

Is this possible? Or is there another way I should be approaching this problem?

Filipe Machado Carneiro · Accepted Answer · 2019-09-22 15:18:31Z

2

You can't use the same port in two different containers, you always have to expose a different port.

To configure ngnix you must install it on your host, then go to the folder:

/etc/ngnix/sites-enabled

Then create a .conf file with the specifications that ngnix will use. Example:

myapi.conf

server {
  server_name mywebsite.com;
  access_log  /etc/nginx/mywebsite.log;

  location / {
      proxy_pass http://127.0.0.1:9003;
      proxy_set_header Host $host;
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
  }
}

In this example, all traffic that arrives through the site mywebsite.com will be directed to the container that has port 9003 exposed. I hope I helped you

answered Sep 22, 2019 at 15:18

Filipe Machado Carneiro

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Comments

David Maze · Accepted Answer · 2019-09-22 15:59:35Z

2

There's nothing special about port 8080 in your example and you can just directly pick the host port you want to use for your separate Compose-based applications. You have to pick different published ports for each Compose setup or the containers won't be able to start at all.

If your setup is that the host nginx contacts the "frontend" container, and then that forwards some requests on to the "backend" container, then you just need to pick the port number you want for the frontend, and you don't need to expose the backend.

version: '3'
services:
  frontend:
    build: ./frontend
    ports:
      # Pick a different port "5000" for each setup
      - 5000:80
  backend:
    build: ./backend
    # Use default command:, working_dir: from image
    # Could publish ports: if necessary
    depends_on:
      - frontend
# Use "default" Docker network

If you do need to directly contact the backend from the outside, you could expose it via the host nginx proxy in the same way and publish ports: from it, again picking distinct ports for each container stack.

Between the two containers, if backend needs to call frontend, it can always use the Docker Compose service name and the port inside the container: http://frontend:80/. You don't need expose: or ports: for this to work.

answered Sep 22, 2019 at 15:59

David Maze

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2 Comments

jeninja Over a year ago

I can work with the idea of setting different ports for my front end. This gets a little tricky with the backend services though. As I will most likely be using port 3000 for all my backends (I usually go localhost:3000, localhost:3001 etc for all my services per web application). http://backend:80/ sounds interesting, any links where I can read more about this topic?

David Maze Over a year ago

Networking in Compose in the Docker documentation is a reasonable starting point, and describes the DNS mechanism. Note that if your frontend serves up something that runs in a browser, the browser isn't in Docker and isn't aware of Docker networking at all, so it needs to point at the nginx proxy you're deploying.

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