Allow using an additional persistence unit and datasource

[pedroigor]

Discussed in #10547

^{Originally posted by dasniko March 2, 2022}
In the server development docs at https://www.keycloak.org/docs/latest/server_development/index.html#leveraging-jakarta-ee it is mentioned how Jakarta EE resources can be used in a User Storage Provider. There‘s also the quickstart-example https://github.com/keycloak/keycloak-quickstarts/tree/latest/user-storage-jpa

With the Quarkus-based distribution of Keycloak, usage of Jakarta EE APIs like session/stateless beans is no longer possible, like also mentioned here: https://www.keycloak.org/migration/migrating-to-quarkus (end of the document).

With Quarkus it is possible to configure multiple database connections.
Will this also be the case for Keycloak itself with Keycloak config params?
And how can/will these database connections be used in a User Storage Provider? Or will this no more be possible in current Keycloak versions? What about the documentation and quickstart-examples?

If this won‘t be possible anymore, it would mean to break many custom User Storage Provider implementations. Users/customers are already starting to complain in other forums:

• https://keycloak.discourse.group/t/keycloak-17-0-0-help-on-creating-additional-datasource-for-custom-user-provider/13684
• https://keycloak.discourse.group/t/keycloak-x-user-storage-spi/12827
• https://keycloak.discourse.group/t/datasource-dependency-injection-in-custom-user-storage-provider/13972
• https://groups.google.com/g/keycloak-user/c/4hlvCttit04
• https://stackoverflow.com/questions/71267230/register-additional-persistence-unit-in-keycloak-quarkus

Can you please give us an update to this?

[pedroigor]

Some initial changes to make the quickstart work are here https://github.com/pedroigor/keycloak-quickstarts/tree/issue-10579.

I'm going to be looking now how to make the changes less painful for those migrating from Wildfly.

[beus]

Thanks for your answers. I will see this :)