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I have a directory(maybe later volume), that I would like to share with all my interactive containers. I know, that native Docker volumes are stored under /var/lib/docker/volumes and docker run -v seems the easiest way, but I think Data Volume Container is a much more standardized way. I don't know, how to create this volume container from a directory or an existing another volume. Maybe is it wrong method?

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There are two ways to create and share volumes: 1. using the VOLUME instruction on the Dockerfile. 2 Specifying the -v <volume_name> option during container runtime and later using --volumes-from=<container> with every subsequent container which need to share the data. Here is an ex with the later:

  1. Start your first container with -v, then add a test file under the directory of the shared volume. 
docker run -it -v /test-volume --name=testimage1 ubuntu:14.04 /bin/bash root@ca30f0f99401:/# ls bin boot dev etc home lib lib64 media mnt opt proc root run sbin srv sys test-volume ===> test-volume dir got created here root@ca30f0f99401:/# touch test-volume/1 root@ca30f0f99401:/# cat > test-volume/1 Test Message!
  1. From the host OS, you can get details of the volume by inspecting your container:

docker inspect ca30f0f99401 | grep -i --color -E '^|Vol'

"Mounts": { "Name": "025835b8b47d282ec5f27c53b3165aee83ecdb626dc36b3b18b2e128595d9134", "Source": "/var/lib/docker/volumes/025835b8b47d282ec5f27c53b3165aee83ecdb626dc36b3b18b2e128595d9134/_data", "Destination": "/test-volume", "Driver": "local", "Mode": "", "RW": true "Image": "ubuntu:14.04", "Volumes": { "/test-volume": {} }
  1. Start another container with a shared volume and check if the shared folder/files exists.
$ docker run -it --name=testimage2 --volumes-from=testimage1 ubuntu:14.04 /bin/bash root@60ff1dcebc44:/# ls bin boot dev etc home lib lib64 media mnt opt proc root run sbin srv sys test-volume tmp usr var root@60ff1dcebc44:/# cat test-volume/1 Test Message!
  1. Goto step-3 to share volume with a new container.
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Make a data volume container by writing a dedicated Dockerfile in which you would:

  • COPY your folder in it
  • declare that copied local container path folder as a VOLUME

Then docker create <imagename> and you get a (created) container, that you can mount in all your other containers, provided you run them with the --volumes-from <containername> option.

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