How to access host OS files from docker container via virtualbox on Windows 10 home

Question

I installed the Docker Toolbox on my Windows 10 home machine. When I hit the quickstart icon, I get a bash shell, and I can run a command like

> docker run -it ruby /bin/bash

That puts me into the bash shell of the docker Ruby container. That container is running on a VirtualBox VM created by the Docker Toolbox. The VM had a shared folder setting with:

Folder Path:  \\?\C:\Users
Folder Name:  c/Users

read-only:  unchecked
auto mount:  checked
make permanent: checked

I would like to be able to access the C:\Users\ folder on my Windows 10 host from my docker container via a directory called /code within the container (which is running Debian Jessie).

How can I configure my VM, or my Docker container to be able to access that folder from my docker container?

Answer 1

The key was figuring out how to express the shared volume which traversed the Windows-VirtualBox boundary, and the VirtualBox-Docker boundary.

Since the shared folder between the VirtualBox VM and Windows 10 home is C:\Users, the mount must be somewhere under that folder tree.

1. I created a folder in windows called C:\Users\Jay\MyApp. This will be visible inside the VirtualBox VM.
2. I then decided to call the folder c/MyApp in the Docker container.

The other key point is that the volume mount must start with "//". So the full docker command is:

docker run -it -v //c/Users/Jay/MyApp:/c/MyApp ruby /bin/bash

I can edit the file called C:\Users\Jay\MyApp\test.rb in Windows, using a nice text editor, and then run it in my Ruby Linux container as

root@ad1e3223e3c7:/# cd c/MyApp
root@ad1e3223e3c7:/c/MyApp# ruby test.rb

The output of test.rb appears on the console of the Docker container.