bfirsh/docker-export-volumes

A Docker image to export volumes from containers running on the same host.

Pass it a container using --volumes-from and it'll output a tarball of the volumes from that container to stdout:

$ docker run --name mycontainer -v /data ubuntu touch /data/test
$ docker run --volumes-from=mycontainer -v /var/run/docker.sock:/var/run/docker.sock bfirsh/docker-export-volumes > volumes.tar
$ tar -tf volumes.tar
data/
data/test

Note: it only works on Docker hosts which listen on a UNIX socket because the image needs to access the host's remote API. In the example above, /var/run/docker.sock is injected into the container as a volume.