keycloak-host-and-realm-chooser

An MVP on how to shard keycloak for massive horizontal parralelization.

This relies on a few pieces working together:

1. An mechanism to resolve an HostRealmIdP object from a username. In this example, an environment variable is parsed into a static map.

2. An custom authorization flow which handles the username before the password is entered. This is realized with the custom UserForm.

3. An app that can handle dynamic keycloak backend configuration. This is realized by sneaking an kc_instance parameter into the redirect_uri and having that parsed by the FE app.

To run it:

$ ./gradlew start
$ ....
$ cd ./app && npm install && npm run dev

Open http://localhost:5173

• log in with foo@foo.com foobar. This will log you in with the default kc0 (on port 8080)
• log in with foo@bar.com foobar: This will log you in on kc in a different kc1 (on port 8081)
• log in with foo@baz.com: This will take you to the realm idp-client on kc0, and because theres an idp_hint, it'll take you straight to the realm idp, where you log in with the pw foobar and are then routed back to idp-client and finally back to the app