It's great to see Kubernetes being integrated more tightly with the AWS ecosystem. If now all cloud providers open sourced their MySQL/PostgreSQL forks...

Are there any good docker compose or helm files out there right now that would work for a nice production ready MySQL or PostgreSQL dB?

It seems like k8s has everything you would need to have the redundant data sources, failover, and point in time recovery options that cloudsql or auroradb have.

The open source database vitess is pretty much designed to be a cloud native production mysql and there are helm charts for it (https://github.com/vitessio/vitess/tree/master/helm) an operator based on the the metacontrollers (https://github.com/vitessio/vitess-operator) and a company called planetscale thats making an operator that has even more features then those two (I work for planetscale and have been building our operator )

I am aware of Crunchy Data doing PostgreSQL-on-Kubernetes:

https://www.crunchydata.com/products/crunchy-postgresql-for-...

We run the official Postgres docker image as a StatfeulSet. Very easy to setup, and we haven’t had any issues with it.

Do you run a single instance Postgres or a cluster? What kind of failure modes have you tested if you’re running a cluster?

Single instance. And we have small scale.