This looks great if you need it to scale but I would like a self contained version that works in a couple of docker containers and doesn’t need a cockroach db cluster in addition to a normal database. Anyway know of anything!?
Depends on what you are looking for.
If you want a standalone auth server, you can use FusionAuth in docker/docker-compose: https://fusionauth.io/docs/v1/tech/installation-guide/docker
You can also package up a library; most major languages have one or more OAuth/OIDC libraries: https://github.com/doorkeeper-gem/doorkeeper for Ruby, https://spring.io/projects/spring-security for Spring/Java, https://oauth2.thephpleague.com/ for PHP, https://pypi.org/project/oauthlib/ for Python.
https://oauth.net/code/ has a further selection of libraries in a variety of languages.