Honest answer: we need to improve the Ruby experience, in general, on App Service before we'd prioritize Ruby support. We want to improve Ruby for App Service in the near future, so I can imagine Ruby support on Functions later on.

Thanks for the reply. One more question: Is it still true that your team must develop service on top of Windows? Can your team use Linux? (I cannot see the direct relationship between these cloud services and Windows, except C# support)

I use a Mac for my daily driver, honestly. We are built on Windows because that's what App Service uses. If App Service adds Linux and Ruby support, we'll definitely light that functionality up on Functions. :)

Microsoft has been more open to Linux lately, so if App Service supports it, then Functions will as well.

I've noticed this as well on all platforms. Google Cloud, Azure, AWS - Python seems to be getting support first.

It might be a chicken and egg problem, but on Azure Web Apps, Python is much more popular than Ruby. This might be because of Windows vs. Linux, but that's where things are at right now.