I know there's Dokku, https://flynn.io/ looked super promising but I think it's basically dead now, same for Deis that is dead and forked to https://web.teamhephy.com/.
This kind of makes sense given how much work it is and how easy it is to monetize as a paid service.
That said, any feedback is more than welcome.
To be clear, I didn't want to say Dokku does things wrong. I'd like something that can validate changes and expected state. But if Dokku is supposed to be a "thin layer", that's cool.
It isn't limited to a single system, and has a scheduler component for Kubernetes (https://github.com/dokku/dokku-scheduler-kubernetes) and Nomad (https://github.com/dokku/dokku-scheduler-nomad).
That said, I would be very nervous to advocate using Dokku for any critical production systems. Are my fears ill founded? Or if not, is there any roadmap to making Dokku production-stable? How can people help?