https://docs.docker.com/compose/compose-file/

command
https://dev.to/serhatteker/how-to-run-multiple-long-commands-in-docker-compose-1f13

docker-compose.yml and docker-compose.override.yml
    -f file1.yml -f file2.yml

    env-vars...
        ports:
            - "${EXTERNAL_PORT}:5000"
            - "#EXTERNAL_PORT:5000"
            # $$... to skip env-vars processing

somename:
  build: folder/
  image: imggrp/imgname:1.0
  image: tonistiigi/dnsdock
  ports:
    - "8761:8761"
  links:
    - postgres:postgres
  hostname: cmp
  links:
    - dnsdock
  dns:
    - 172.17.0.1
  environment:
    - DNSDOCK_NAME=tmp1
    - DNSDOCK_IMAGE=
  volumes:
    - /var/run/docker.sock:/run/docker.sock
  mem_limit: 512m
  mem_reservation: 256m