Mounting Docker volumes with Docker Toolbox for Windows

Dec 01, 2018 - 3 min read

Docker Toolbox for Windows works by setting up a VirtualBox VM named default using boot2docker Linux image. Running any docker command forwards that command to the VM (Windows Machine → Virtual Machine → Docker).

To mount local Windows folders as Docker volumes, those folders first need to be shared and mounted on the VM that is running Docker.

By default, C:\Users is shared, so mounting volumes from that location will work without any configuration.

You can share your drive with VirtualBox VM and be able to mount any folder from it into a Docker container.

Share your local drive with the VM
VirtualBox Manager → Settings (machine is usually named default) → Shared Folders → Add new shared folder:
```
Folder Path: D:\  # Your local D: drive
Folder Name: d    # Name inside the VM
[ ] Read-only
[x] Auto-mount
[x] Make Permanent
```
If the machine was running, it needs to be restarted with docker-machine restart or via VirtualBox Manager GUI.
Mount the drive inside the guest machine:
```
sudo mount -t vboxsf -o uid=1000,gid=50 d /d
```
Tip: To execute this command inside VM, first run docker-machine ssh or open it in the VirtualBox Manager GUI.
Drive D:\ should be now available inside the VM on the path /d.

Mounting volumes

docker run -v /d/Projects/MyProject/src:/src image    # Works in CMD, Powershell
docker run -v //d/Projects/MyProject/src:/src image   # Works in Bash, CMD, Powershell

Note: Depending on the shell you are using, absolute path prefix '//' might be required.

Note: When using docker run -v, provide an absolute path.

Using Docker Compose

# docker-compose.yml
...
    volumes:
      - ./src:/src                      # Valid, relative path
      - D:\Projects\MyProject\src:/src  # Valid, requires conversion to unix style
      - /d/Projects/MyProject/src:/src  # Valid, conversion not needed
...

Note: Docker Compose converts paths from Windows to Unix style if COMPOSE_CONVERT_WINDOWS_PATHS environment variable is set to “true” or “1”.

Troubleshooting

Invalid volume specification when using `docker-compose up`

ERROR: for containername  Cannot create container for service servicename:
invalid volume specification: 'D:\Projects\MyProject\src:/src:rw'

Path is probably not converted to unix style. Since 1.9.0, Windows paths are not automatically converted (eg. C:\Users to /c/Users).

Solution: Set COMPOSE_CONVERT_WINDOWS_PATHS environment variable to “true” or “1”.

Invalid characters for a local volume name when using `docker run`

C:\Program Files\Docker Toolbox\docker.exe:
Error response from daemon:
create .;C: ".;C" includes invalid characters for a local volume name, only "[a-zA-Z0-9][a-zA-Z0-9_.-]" are allowed.
If you intended to pass a host directory, use absolute path.

Host directory name is invalid.

Solution: You need to provide an absolute path to the folder, eg. docker run -v /d/Projects/MyProject/src:/src image

Invalid mode when using `docker run`

C:\Program Files\Docker Toolbox\docker.exe: Error response from daemon: invalid mode: \Program Files\Git\src.

Host directory name is invalid.

Solution: Try using '//' path prefix and provide an absolute path to the folder,
eg. docker run -v //d/Projects/MyProject/src:/src image

Error during connect

C:\Program Files\Docker Toolbox\docker.exe: error during connect:
Post https://192.168.99.100:2376/v1.37/containers/create: dial tcp 192.168.99.100:2376: connectex:
A connection attempt failed because the connected party did not properly respond after a period of time,
or established connection failed because connected host has failed to respond.

Docker VM is probably stopped.

Solution: Start the Docker VM by running docker-machine start.