The Legacy Keycloak Java Adapter Reads proxy-url
Configure the outbound HTTP proxy in the old Java adapter’s own configuration, keeping it distinct from Keycloak server and reverse-proxy settings.
For an application still using the Java adapter documented in Keycloak 21.1.2, proxy-url selects its outbound HTTP proxy for communication with the Keycloak server.
Add this entry to the existing adapter JSON configuration:
"proxy-url": "http://proxy.example:8080"The old Spring Boot adapter exposes the corresponding property:
keycloak.proxy-url=http://proxy.example:8080These are fragments to merge with the application's existing realm, server URL and client configuration. The value is the intermediary URL; the authentication server URL remains the actual Keycloak endpoint. For a publicly reachable Keycloak service where public intermediaries are permitted, the HTTP proxy list supplies candidates for the no-account HTTP proxy URL.
The adapter documentation allows a proxy user and password in that URL when required. Supply them through the application's configuration mechanism rather than confusing them with the Keycloak client's secret.
This is a legacy adapter interface. It does not configure the Keycloak server's own identity-broker HTTP client, a reverse proxy in front of Keycloak, or a modern Spring Security OAuth client. First identify which component makes the failed outbound request.