This is just a Proof of Concept and not recommended for production use. Nevertheless it is a great way develop and test Keycloak extensions or generally playing with Keycloak.
To start the sample application just build the project with:
mvn package
and start the spring boot app via:
java -jar target/spring-boot-keycloak-server-*.jar
The embedded Keycloak server is now reachable via http://localhost:8080/auth.