Connecting Keycloak to user DB

[NoahNL]

When using Keycloak for an existing service, is it common to merely use Keycloak as an authentication service and use your regular database for the users that you had prior to using Keycloak?

[dasniko]

That’s a valid use-case and many customers of mine are using this.
You can implement the UserStoragProvider SPI to connect agains any datasource you like.
See also my answer here:

Is it possible, without JDBC to link user table?

Yes, that’s of course possible! As you are implementing code, you can do whatever you want. Actually, you then don’t connect against your table, but against the API, which will run in front of your database/table. See my examples here, look for flintstones-userprovider, it makes requests against an HTTP API. See also my video on YouTube: [KEYCLOAK Implementing Custom User Storage Provider (in-depth) | Niko Köbler (@dasniko)]