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?
To attach a volume into a running container, we are going to: use nsenter to mount the whole filesystem containing this volume on a temporary mountpoint; create a bind mount from the specific directory that we want to use as the volume, to the right location of this volume; umount the temporary mountpoint.
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.
That´s it :)
We don't have any way to add volume in running container, but to achieve this objective you may use the below commands:
Copy files/folders between a container and the local filesystem:
docker cp [OPTIONS] CONTAINER:SRC_PATH DEST_PATH docker cp [OPTIONS] SRC_PATH CONTAINER:DEST_PATH
For reference see:
https://docs.docker.com/engine/reference/commandline/cp/
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