How to autoscale gitlab-runner windows shell executors with aws machines

Description

Hi,
I followed this guide here to run some autoscaled docker+machine instances running on linux and spot instances, pretty cool.

But I was wondering if it's possible to set amazonec2-ami machine parameter to a windows ami and have gitlab-runner handle windows machines as shell executors. I still have a few things I want to try on my own, but I did not find any related documentation or similar attempt.

Proposal

• Document how to autoscale gitlab-runner windows executor with AWS or something like that
• Make it possible to have a gitlab-runner configuration that can create or use windows machines in a cloud at low cost

Why and background

I'm the main author behind gableroux/unity3d-gitlab-ci-example and it turns out unity can't build for video game consoles on Linux so builders have to run on windows. Most of the folks automating unity builds are spinning Jenkins servers and do a lot of manual setup, install things and tools manually on a Windows machine that sleeps in the corner of a room. Been there, done that and I think it can be better with the tools we have today.

Concerning unity on windows with automation, I already have a good proof of concept here running in a different CI, but let's focus on running autoscalled windows executors first. ;)

Links to related issues and merge requests / references

Haven't found any, but feel free to share related links