Docker-compose multiple services listen on same port, different domains

Question

How can I have multiple docker services listening on same ports, only using different domains?

Is it even possible to define in docker-compose or do I need to have just one service listening on the port and then rerouting the traffic to respective services depending on the domain?

---

This example is failing since it's listening on the whole network (instead of just the domains)

docker-compose up
Creating network "test-docker_default" with the default driver
Creating test-docker_static_1 ... done
Creating test-docker_app_1    ... 
Creating test-docker_app_1    ... error

ERROR: for test-docker_app_1  Cannot start service app: driver failed programming external connectivity on endpoint test-docker_app_1 (ef433ffad1af01ffa31cd8a69a8c15b69ca7e7b6935924d34891b92682570e68): Bind for 0.0.0.0:80 failed: port is already allocated

ERROR: for app  Cannot start service app: driver failed programming external connectivity on endpoint test-docker_app_1 (ef433ffad1af01ffa31cd8a69a8c15b69ca7e7b6935924d34891b92682570e68): Bind for 0.0.0.0:80 failed: port is already allocated

docker-compose.yml

version: '3.3'
services:

  app:
    image: node
    depends_on:
      - static
    networks:
      default:
        aliases:
          - app.localhost
    ports:
      - 80:80

  static:
    image: nginx
    networks:
      default:
        aliases:
          - static.localhost
    ports:
      - 80:80

/etc/hosts

127.0.0.1    app.localhost
127.0.0.1    static.localhost

Answer 1

You can map only one container to the same port of the host. If you want to map 2 services on same host port, you should use a reverse proxy like Traefik (well integrated with docker). The reverse proxy will listen the host port 80, then forward to a specific docker container on port not mapped to the host depending some defined rules like aliases, url path.

Answer 2

You should use a reverse proxy. You can for instance give a look to jwlider/nginx on dockerhub.io, documentation is quite good !