test-docker-compose.yml

version: '2'

services:
  some_container:
    image: ubuntu
    command: sleep infinity
    networks:
      - web
  whoami:
    image: emilevauge/whoami
    network_mode: "service:some_container"
    labels:
      - "traefik.backend=whoami"
      - "traefik.port=80"
      - "traefik.frontend.rule=Host:whoami.docker.localhost"

networks:
  web:
    external:
      name: traefik_webgateway

traefik-docker-compose.yml

version: '2'

services:
  proxy:
    image: traefik
    command: --web --docker --docker.domain=docker.localhost --logLevel=DEBUG
    networks:
      - webgateway
    ports:
      - "80:80"
      - "8080:8080"
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - /dev/null:/traefik.toml

networks:
  webgateway:
    driver: bridge