I know this question is old, but I just came across the same problem. While the solution from This answer did not work directly, I just tried setting the config http-host=127.0.0.1 (not publically documented) in keycloak.conf and it seems to work for me. Probably also works equally using keycloaks other config variants. If I were to guess, keycloak manually overrides quarkus.http.host with its own internal default.