stack: user/stackname
version: 0.1.1
variables:
  foo:
    type: string
    value: foofoo

services:
  wordpress_stateful:
    image: image
    stateful: true
    volumes:
      - wp-data:/var
  wordpress_stateless:
    image: image
    stateful: false
    volumes:
      - wp-data-ext:/var
      - wp-data-ext-2:/var/lib

volumes:
  wp-data:
    driver: local
    scope: instance
    driver_opts:
      foo: bar
  wp-data-ext:
    external: true
    scope: instance
  wp-data-ext-2:
    external:
      name: $foo
    scope: instance