Free up disk space caused by Docker files

FreeDockerDiskSpace.ps1

# :: Prune dangling (untagged) images
docker image prune

# :: Stop Docker Desktop
Stop-Service 'com.docker.service'

# :: Stop the WSL service to ensure that doesn't lock the file
wsl --shutdown

# :: Note: If docker desktop is running you may get a warning at this point... I couldn't find a clean way to stop that via the command line

# :: Now reduce the disk size (pwsh cmdlet needs the hypver v features installed: https://superuser.com/questions/1307441/powershell-resize-vhd-is-not-recognized-as-the-name-of-a-cmdlet/1307442#1307442)
Optimize-VHD -Path (Join-Path -Path $env:LOCALAPPDATA -ChildPath 'Docker\wsl\data\ext4.vhdx') -Mode Full

# now you can right click docker desktop and hit restart docker if you want to use the services again.
# I've not restarted them via this script, as chances are you're not actively using docker if you're working on your disk space.

Move VHDX

# Instead of just freeing up space, another option is to move the VHDX file elsewhere
# per https://github.com/docker/for-win/issues/7348
# documentation: https://docs.microsoft.com/en-us/windows/wsl/basic-commands#import-a-new-distribution

# get a list of all wsl distros
wsl -l -v 
# Returns something like this:
#    NAME                   STATE           VERSION
#  * Ubuntu                 Stopped         2
#    Alpine                 Stopped         2
#    docker-desktop         Stopped         2
#    docker-desktop-data    Stopped         2

# stop the running wsl instance
wsl --shutdown

# export the image (the content of the vhdx) to a file by using an distro name from the list above (e.g. `docker-desktop-data`)
wsl --export docker-desktop-data X:\temp\docker-desktop-data-temp.tar

# remove the existing docker data (i.e. vhdx file)
wsl --unregister docker-desktop-data

# re-import that data specifying the new folder for the vhdx file and the tar file we used to temporarily store that data
wsl --import docker-desktop-data Y:\path\to\vhdx\parent\directory\ X:\temp\docker-desktop-data-temp.tar --version 2

# after this, the tar file can be deleted; as it was only required as a staging area for transitioning the data.

# repeat for any other distros to be moved.

# Another option could be to export them files to tar files as above, then compress them / store them on slower storage, then extract and reimport them to your faster drives when you need them