docker-compose, extend

docker-compose.yml

version: "3.8"

x-superenv:
  &default-superenv
  environment: 
    XX: 135
    FOO: superenv-foo
  command: echo $${XX} $${FOO}

services: 
  echo: &echo-base
    container_name: echo
    image: alpine:latest
    restart: always
    command: 
      - sh
      - -c
      - echo $$XX && tail -F /xxx.log
    environment: 
      XX: 123
  echo2:
    <<: *echo-base
    container_name: echo2
    environment: 
      XX: 456
  echo3:
    <<: *echo-base
    container_name: echo3
    environment: 
      XX: 789
  run1:
    <<: *default-superenv
    image: alpine:latest
  run2:
    <<: *default-superenv
    image: alpine:latest
    command: 
      - sh
      - -c 
      - echo $$FOO