Volumes and docker-compose

Question

I'm trying to create a docker-compose.yml file that contains a --volumes-from instruction. Does anyone know the syntax?

I have been looking online for some time now, and it appears that the --volumes-from command is only available as a docker command. I hope I'm wrong.

Answer 1

February 2016:

The docs/compose-file.md mentions:

Mount all of the volumes from another service or container, optionally specifying read-only access(ro) or read-write(rw).

(If no access level is specified, then read-write will be used.)

volumes_from:
 - service_name
 - service_name:ro
 - container:container_name
 - container:container_name:rw

For instance (from this issue or this one)

version: "2"

services:
...
  db:
    image: mongo:3.0.8
    volumes_from:
      - dbdata
    networks:
      - back
    links:
      - dbdata

 dbdata:
    image: busybox
    volumes:
      - /data/db

---

Note August 2017: with docker-compose version 3, regarding volumes:

The top-level volumes key defines a named volume and references it from each service’s volumes list.
This replaces volumes_from in earlier versions of the Compose file format. See Use volumes and Volume Plugins for general information on volumes.

Example:

version: "3.2"
services:
  web:
    image: nginx:alpine
    volumes:
      - type: volume
        source: mydata
        target: /data
        volume:
          nocopy: true
      - type: bind
        source: ./static
        target: /opt/app/static

  db:
    image: postgres:latest
    volumes:
      - "/var/run/postgres/postgres.sock:/var/run/postgres/postgres.sock"
      - "dbdata:/var/lib/postgresql/data"

volumes:
  mydata:
  dbdata:

This example shows a named volume (mydata) being used by the web service, and a bind mount defined for a single service (first path under db service volumes).

The db service also uses a named volume called dbdata (second path under db service volumes), but defines it using the old string format for mounting a named volume.

Named volumes must be listed under the top-level volumes key, as shown.