How to use this image to expose volumes to other containers?

[Marco Pegoraro]

Hi Justin, I'm trying to tail the docker logs from a Node app.

Of course the problem seems to access the files itself, and your project looks a promising step toward a solution.

Is there a way to have your project expose /var/lib/docker as a volume that could be inherited by other containers?

[Justin Cormack]

Why can't you just do docker run -v /var/lib/docker:/var/libdocker ... to share this?

[Marco Pegoraro]

Hej, I'm not sure what do you mean. Here is a pseudo-coded docker-compose that express what I aim for:

services:

  nsenter1:
    image: justincormack/nsenter1
    ...

  myservice:
     image: foo
     volumes_from: nsenter
     volumes:
       - /var/run/docker.sock:/var/run/docker.sock

"myservice" should then be able to access host's docker info and logs even on MacOS.
Right now I've build a small utility that tries to tail the log files (on linux) and falls back on child process spawning a docker logs -f that give or takes works, but I read around is less efficient compared to tailing the files.

Marco

[Deleted user]

@justincormack I have the same question.

When I run docker run -it --rm --privileged --pid=host -v /var/lib/docker:/var/lib/docker justincormack/nsenter1 or any other host:guest combo, the folders don't link.

If the folders exist on both the host and the guest, the data isn't mirrored

Any ideas?

[Armando Lüscher]

I'm wondering if anybody has managed to extract data from host image.

I've obviously tried to mount a volume, but as the previous commenter, it doesn't work.
docker run -it --rm --privileged --pid=host -v /var/lib/docker:/var/lib/docker justincormack/nsenter1

I then tried to just docker cp stuff out of there, but again that doesn't work.
Being relatively new to the more techie side of Docker, I don't understand why.

Interestingly, doing docker cp nsenter-container:/etc . copies only a handful of files, not the whole /etc folder.

Does anybody reading this know more?

[Justin Cormack]

Hi I made another repo that will dynamically add mounts to containers from any other namespace, including root and another container https://github.com/justincormack/addmount - its not the most polished UI, but it does work.