Completely agree. I don't know where or how people started thinking that putting a stateful service inside of a stateless container was a best practice, but no one should be doing that in production.
I wouldn't contemplate it, except that I'm looking at migrating a Rails/Postgrep app to GKE, and containerizing PG seems like the lowest-friction path. Are there better alternatives for getting to GKE, or is GKE a bad fit for this scenario?
As I said, if it is really as obvious as you say it is, please point me to a single mention in official documentation that databases should not be containerized.
Why would documentation about docker include basic fundamental knowledge about deploying services in production? This isn't docker knowledge, this is service based architecture 101. Why is it docker's responsibility to teach you general software engineering concepts?