With Quarkus, they went into other extreme -- if you are using docker, to get as fast startup as possible, you have to build your image with your configuration/modules used baked in.

Overall, I'm pretty satisfied. There are some bumps, but they are not Keycloak fault (having two different keytabs for two different host names for two different container images sharing same IP and reverse name not matching is kind of difficult).

There is an auto-build option so building a custom Docker image is an optimisation.