implement keycloak in docker for tutorial

[tvogel8570]

I try to leverage docker as much as possible to keep current versions of software and reduce the impact of locally installed development software. This PR has the setup to use a dockerized Keycloak for the tutorials.

Note this is my very first PR on any project so please give me any feedback to improve.

[ch4mpy]

I have to think a bit about his one: on the one hand, the aim of this repo is not to illustrate every possible deployment of every OIDC authorization server, but on the other hand, I'm not sure I ever read a short tutorial for setting up a local development Keycloak instance on Docker with a self-signed SSL certificate.

If we add this one, we should probably add one for K8s too (for instance using Docker-Desktop one)...

What do you think of creating such tutorials on your own Github account and modifying this PR to contain only links to your own repo(s)?

[tvogel8570]

I created a public GitHub repo for this solution. It is here. I significantly revised the README.md to be generic rather than fit into your repo.

I've never worked with K8s / swarm. I'll look to add it in the future.

I'm not sure how to modify this PR to best work on your site. Please make a recommendation how you think this PR should be revised or add a link to my repo in the appropriate place.

[ch4mpy]

I was thinking of removing what you put under infrastructure and editing the Keycloak README (the /samples/tutorials/keycloak.md) to insert links to your own tutorial(s) with a short description of the target deployment (docker running on localhost with self-signed certificate, or whatever else you provide).

What do you think?

[ch4mpy]

Replaced this PR with the following content in Keycloak tutorials README:

2. Keycloak in docker

You may refer to the official documentation or to this tutorial written by Timothy Vogel (who also contributed to improve this repo documentation)