What kills rails for me at the moment is the time it takes to start up. I'd love to be able to use on top of things like cloud run where resources ramp down to zero when there are no requests, but the startup time makes this very difficult.
(I have not actually used this myself). The folks over at CustomInk maintain Lamby, a project to run Rails in a quickly-bootable Lambda environment. Might be worth checking out, if you otherwise do enjoy working with Rails: https://lamby.custominktech.com
I dislike that too. I've started using Sinatra for ruby apps instead of rails. You end up writing a lot more boilerplate but startup times are near instant and the API is great. Also it's highly stable. I haven't had to update my Sinatra apps (beyond updating dependent gems) in many years.
While I've not tried it personally, Django can be run like this. It being a "full app" doesn't preclude it from having a fast enough startup to allow for cloud function deployment.
You might try caching bootsnap in the Docker image. I didn’t realize this was possible until I saw it in the Dockerfile that Sam and DHH cranked out recently.
