How can I mount a container file to my Docker host?

Question

I'd like to mount a file from a Docker's container to my docker host.

Data volumes is not the solution for me, as these are mounts from the docker host to docker containers, and I need the opposite way around.

Thanks

Answer 1

When docker mounts a volume, it overlays the directory inside the container with that of the volume. There is an exception where it will initialize a named volume with the content of that directory in the image. There's no other built in method to copy files out of the image to the volume.

Therefore, to go the other direction and copy the contents of the image directory out to the host with a host volume, you'll need to add your own copy command inside the container. That can be part of your entrypoint script that runs in the container.

An example of the entrypoint script is the volume caching scripts in my base image. One script moves the files to a cached location inside the image during the build, and a second script copies files from the image cached location to the volume mount in the entrypoint.