WSL2 mount VHDX virtual disk issue with Windows docker Volumes

Question

On Windows 10 Insider Preview (prerelease.201207-1443) I have mounted successfully a vhdx file with WSL2.

PS C:\Users> wmic diskdrive list brief
Caption                     DeviceID            Model                       Partitions  Size
..
Microsoft virtuális lemez   \\.\PHYSICALDRIVE2  Microsoft virtuális lemez   1           5362882560

PS C:\Users> wsl --mount \\.\PHYSICALDRIVE2 --bare

Inside the Ubuntu 20.20 it looks OK, I could mounted and format (ext4) the virtual disk.

/dev/sde1       4.9G   20M  4.6G   1% /mnt/docker/vol/pg_disk_1

I can use it, read, write without any problem. Performance is good.

Issue: I want to use this disk when I create docker container for application data, it is not visible inside the container.

docker run -d -it --name devtest --mount type=bind,source=/mnt/docker/vol/pg_disk_1/nginx,target=/app nginx:latest

docker inspect shows the volume bind mounted:

        "Mounts": [
        {
            "Type": "bind",
            "Source": "/mnt/docker/vol/pg_disk_1/nginx",
            "Destination": "/app",
            "Mode": "",
            "RW": true,
            "Propagation": "rprivate"
        }
    ],

when I create a file on the host eg. example_host.html

User@Pince:/mnt/docker/vol/pg_disk_1/nginx$ ls -l
total 0
-rw-r--r-- 1 r858 r858 0 Jan  3 11:30 example_host.html

not visible when I check inside the container

root@078e4d7007a8:/app# ls -la
total 8
drwxr-xr-x 2 root root 4096 Jan  3 10:32 .
drwxr-xr-x 1 root root 4096 Jan  3 10:15 ..
root@078e4d7007a8:/app# pwd
/app

and if I create a file here inside the container it will be persistent when recreate the container but not in Linux mounted disk. I found it here:

\\wsl$\docker-desktop\mnt\host\wsl\docker-desktop-bind-mounts\Ubuntu-20.04\...

Question: this is normal and I missed something or it is not ready yet in this stage of the development. And do you know anybody a workaround how to use vhdx mounted disk for docker application data on Windows?

Answer 1

The problem is that /dev/sde1 is created and managed by wsl, so not (easily?) accessible by Windows programs like Docker Desktop.

One workaround is to mount \.\PHYSICALDRIVE2 as drive D: and mounted as :

docker run -v 'D:\data:/data' ...

This way, you can access it both on Windows and wsl.