Running a traditional relational DB inside a container is pretty stupid. It can take a while for those suckers to stop & start and they often don't work proper

Running a traditional relational DB inside a container is pretty stupid. It can take a while for those suckers to stop & start and they often don't work properly if placed behind a load balancer with random distribution of connections. Also, if a connection gets cut off in the middle of a transactions things can go very, very wrong. On the other hand, if you architect your database usage in such a way as to ensure that cutoff transactions get detected and retried without relying on persistent connections it can be a good idea to use containers for hosting your database(s). Of course, your use case needs to fit this kind of model for it to work. If your use case requires mostly serial transactions and can't work with "eventual consistency" then containers are probably a no-go.