Setup:
Keycloak 20.0.3
Spring Boot 2.7.7 with keycloak-spring-boot-starter
application.properties (partial):
keycloak.proxy-url=http://localhost:31127/auth/
keycloak.auth-server-url=http://localhost:31127/auth/
The URL for the config is accessible from the browser. However, the keycloak adapter tries to read the config from the keycloak server, but doesn’t find it because the host is apparently prepended to the URL (debug log from http client):
org.apache.http.headers : http-outgoing-2 >> GET http://localhost:31127/auth/realms/dundee/.well-known/openid-configuration HTTP/1.1 org.apache.http.wire : http-outgoing-2 << "{"error":"RESTEASY003210: Could not find resource for full path: http://localhost:31127http://localhost:31127/auth/realms/myrealm/.well-known/uma2-configuration"}"
Other calls do not have the host prepended and succeed, as in
org.apache.http.headers : http-outgoing-1 >> PUT /auth/admin/realms/dundee/clients/e94556....
I don’t know where to remove the host for the GET (or set it correctly to /auth/realms/...) in the first place; that call goes out to the server before any of my custom code is executed.