> But if you already run everything in docker and really want to get rid of puppet, then why not?

And you know, I wouldn't argue too much at the thought of running MySQL out of a container. It does avoid a lot of basic issues around upgrades, versioning, stack split, etc. It's the act of treating it like all other containerized software which gets my panties in a twist.

Stateful systems can't be treated like stateless systems if you want to maintain anything resembling reasonable uptime and performance.