> My issue with Github CI is that it doesn't run your code in a container.

Is this not what you want?

https://docs.github.com/en/actions/how-tos/write-workflows/c...

> You just have github-runner-1 user and you need to manually check out repository, do your build and clean up after you're done with it. Very dirty and unpredictable. That's for self-hosted runner.

Yeah checking out everytime is a slight papercut I guess, but I guess it gives you control as sometimes you don't need to checkout anything or want a shallow/full clone. I guess if it checked out for you then their would be other papercuts.

I use their runners so never need to do any cleanup and get a fresh slate everytime.