Is there a way to make WSL stop using a distro's filesystem file so that that distro can be exported?

[adamkpickering]

Hello! I am a Rancher Desktop developer. Similar to Docker Desktop, Rancher Desktop uses WSL on Windows to run Linux containers.

In our next release, we plan to include a "snapshots" feature. This will allow a user to take a snapshot of the state of Rancher Desktop, and restore to that snapshot later. In order to do this, Rancher Desktop uses wsl.exe --export and wsl.exe --import.

Of course, before exporting the distro that Rancher Desktop uses behind the scenes, that distro must not be in use. We currently achieve this by using wsl.exe --terminate. Prior to snapshots, this approach worked well. With snapshots, our approach looks like this:

1. Shut down the backend (which includes wsl.exe --terminate).
2. Create a snapshot (which includes wsl.exe --export).
3. Restart the backend.

But I am running into a problem. When I try to run wsl.exe --export immediately after shutting down the backend, I run into the following error:

The process cannot access the file because it is being used by another process.
Error code: Wsl/Service/0x80070020

From this, I understand that something is still using the distro's filesystem file (ext4.vhdx). In testing, I need to wait 50s-1m for whatever is using this file to stop using it. It also seems that a failed run of wsl.exe --export resets this process - I have to wait another 1m in order for it to work.

Is there any way of monitoring/expediting this process of giving up the file? I am finding that there is not a lot of documentation out there about this mechanism. Thanks!

[Yewzir]

@adamkpickering

Instead of wsl.exe --terminate, I think what you need is wsl.exe --shutdown. The former command stops a distribution from running, or terminates it. The latter command, however, forces instant termination of all running distributions, continuously running background processes and the WSL 2 lightweight utility virtual machine.

Kind regards
Yewzir