Is a self-hosted Windows runner even possible?

[JanikHelbig-NB]

Hi!

I'm currently trying to set up a bare-metal, self-hosted Windows runner for workflows using unity-builder@v4. However, I keep running into issues and I'm starting to wonder if it's been futile from the start.

I'm a bit confused by the documentation in regards to this. The guide for setting up a self hosted runner in the Game-CI docs makes no mention of windows at all and the GitHub Actions documentation states here that "you must use a Linux machine" to use actions utilizing docker containers. (Which I assume refers to actions such as this.)

For a little more context, I'm running into this error:

...
Building locally
"C:\Program Files\Docker\Docker\resources\bin\docker.exe" run --workdir c:/github/workspace --rm ((flags omitted for brevity)) powershell c:/steps/entrypoint.ps1
docker: Error response from daemon: the working directory 'c:/github/workspace' is invalid, it needs to be an absolute path.
See 'docker run --help'.
Error: Build failed with exit code 125

This error does not occur when running the same workflow on a GitHub-hosted Windows runner. I'm not sure if this is an issue I can fix on my end or if there is some magic happening with GitHub's runners that I don't understand.