I used runV with drone.io (on top of Media) to run distributed on-demand VM builders for GitHub enterprise (we were building physical machine images to deploy so needed VM isolation).
It actually worked great, and I've struggled to get as quite a flexible CI system at other jobs since then (the big advantage was it looked like Docker, so with compose you could either spin a metal-like nested VM or just pull in some DB containers in your build instance).
It actually worked great, and I've struggled to get as quite a flexible CI system at other jobs since then (the big advantage was it looked like Docker, so with compose you could either spin a metal-like nested VM or just pull in some DB containers in your build instance).