Linux – Pull a file from a Docker container

dockerlinux

I can see that it's possible to insert a file into a Docker container via insert:

docker insert IMAGE URL PATH

Is there a way to fetch the contents of a file in a Docker container and save them somewhere on the host operating system? I'd like to extract the value of a configuration file and store it on my host operating system.

Best Answer

Depends on which version of the docker tool you're using:

The current version has an ordinary 'cp' command, according to cp doc v0.6.3:

Usage: docker cp CONTAINER:PATH HOSTPATH
Copy files/folders from the containers filesystem to the host
path. Paths are relative to the root of the filesystem.
For older version, you may consider to use 'export' as from export doc v0.5.3:

Usage: docker export CONTAINER
Export the contents of a filesystem as a tar archive

(There may also be other options, based on capabilities of your container.)

Related Solutions

Docker Container Volumes Synced Locally

If you're using the official registry image, the path at which the local volumes are stored by default is /tmp/registry. Thus that should be your mount point.

docker run -d -p 5000:5000 --name td-registry -v /Users/andrew/Dropbox/Developer/Docker/Registry:/tmp/registry registry

This is covered in the persistent storage section of the main readme.

Docker container with Samba exits without any message

The container will exit without any comment, unless you increase the debug level. You can use something like --debuglevel=4.

Once you do that, rebuilt and restart the container you will should get something at the end like:

Server exit (EOF on stdin)

And that points to the solution, change the smbd invocation to:

exec ionice -c 3 smbd -FS < /dev/null

and your container should no longer directly exit.

I am not sure what causes this backwards incompatible change, nor why this was not tested against existing dockerhub entries.

I had two of my containers break as well on upgrading to 1.11. and on downgrading to 1.10.3, ran into the dreaded Cannot stop container .... Container does not exist: container destroyed bug. I had to stop docker, clear all of the history, so I cannot really recommend that.

Best Answer

Related Solutions

Docker Container Volumes Synced Locally

Docker container with Samba exits without any message

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