This is a list of resources for all thingz stateful apps and tooling in and for Kubernetes. I did an initial dump of my bookmarks here but would really appreciate it if you heavily PR it, or if you don't feel comfortable doing this, at least raise an issue for what's missing. If you send in suggestions or update the resources directly, please also add yourself to the list of contributors using a website, an mail address or a Twitter handle to sign off.
Note: when you read in-tree it means it's part of the Kubernetes source code, otherwise we call it 3rd-party, that is, using some kind of Kubernetes extensibility mechanism.
Official Kubernetes docs and specifications.