Mount a local directory as volume in container, from the Dockerfile

Question

I know how local directories can be mounted as volumes with the -v option in docker run, i.e.

docker run -v /local/some_folder:/container/some_folder image_name

However, I want to be able to specify the above instruction (to mount the local /local/some_folder as /container/some_folder in the container within the Dockerfile.

---

I've tried using VOLUME /local/some_folder /container/some_folder in the Dockerfile, but that didn't seem to work: I am then able to access /container/some_folder from within the container using docker exec -t container sh, but the write changes of container to /container/some_folder are not reflected in /local/some_folder during container runtime AND after docker stop container.

Answer 1

You do not have access to control things like host volume mounts inside the Dockerfile or image build process. Allowing this would allow malicious image creators to make an image that mounts directories on the host without the permission of the admin of that host. A security breach that allowed a popular base image to mount the filesystem could be used to send private data off-site and inject login credentials on countless machines. The only way to mount a volume is at run time at the explicit request of the admin running the container, and to the directory they provide.