[FIXED] How can I add a volume to an existing Docker container?

Issue

I have a Docker container that I've created simply by installing Docker on Ubuntu and doing:

sudo docker run -i -t ubuntu /bin/bash

I immediately started installing Java and some other tools, spent some time with it, and stopped the container by

exit

Then I wanted to add a volume and realised that this is not as straightforward as I thought it would be. If I use sudo docker -v /somedir run ... then I end up with a fresh new container, so I'd have to install Java and do what I've already done before just to arrive at a container with a mounted volume.

All the documentation about mounting a folder from the host seems to imply that mounting a volume is something that can be done when creating a container. So the only option I have to avoid reconfiguring a new container from scratch is to commit the existing container to a repository and use that as the basis of a new one whilst mounting the volume.

Is this indeed the only way to add a volume to an existing container?

Solution

You can commit your existing container (that is create a new image from container’s changes) and then run it with your new mounts.

Example:

$ docker ps  -a

CONTAINER ID        IMAGE                 COMMAND                  CREATED              STATUS                          PORTS               NAMES
5a8f89adeead        ubuntu:14.04          "/bin/bash"              About a minute ago   Exited (0) About a minute ago                       agitated_newton

$ docker commit 5a8f89adeead newimagename
$ docker run -ti -v "$PWD/somedir":/somedir newimagename /bin/bash

If it's all OK, stop your old container, and use this new one.

You can also commit a container using its name, for example:

docker commit agitated_newton newimagename

That's it :)

Answered By - Leonardo Cuquejo

Answer Checked By - David Goodson (PHPFixing Volunteer)