Mount docker volume subfolders

Question

I have a docker image that requires lots of data. This data is on different physical drives but symlinks are used to make it look like it's all on a single drive. So physically on the host machine there is a drive structure as follows:

/Data
/Data1
/Data2
/DataN

Logically I use symlinks to move various pieces of /Data1/subfolder1 into /Data/subfolder1. So in /Data there is a symlink to /Data1/subfolder1 and similar symlinks for /Data2 ... /DataN.

It seems that just mounting the /Data volume doesn't give the docker container access to the /Data2 ... /DataN physical drives via the symlink.

docker run -v /Data:/Data:ro

So I tried manually mapping each of the symlinks in the docker run command:

docker run -v /Data:/Data:ro -v /Data1/subfolder1:/Data/subfolder1

This didn't seem to work either. Is what I'm trying to achieve possible with docker? Maybe they need to be mounted in a different configuration to prevent overlapping folders?

I'm running Ubuntu 14.04 and the application running inside the docker image is a mono 4.0.5.1 application. Docker version is 1.9.1.

Answer 1

Instead of using symlinks to achieve the desired folder structure, you can mount the drive where they're needed. This can be accomplished using the mount -o bind or also by editing the /etc/fstab file.

Using mount :

mount -o bind /Data1/subfolder1 /Data/subfolder1

Using /etc/fstab :

/Data1/subfolder1 /Data/subfolder1 none bind 0 0