7.10. User Caches

When a user object is loaded by ID, username, or email queries it is cached. When a user object is being cached, it iterates through the entire UserModel interface and pulls this information to a local in-memory-only cache. In a cluster, this cache is still local, but it becomes an invalidation cache. When a user object is modified, it is evicted. This eviction event is propagated to the entire cluster so that the other nodes' user cache is also invalidated.

7.10.1. Managing the user cache

You can access the user cache by calling KeycloakSession.userCache(). 

/**
 * All these methods effect an entire cluster of Keycloak instances.
 *
 * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>
 * @version $Revision: 1 $
 */
public interface UserCache extends UserProvider {
    /**
     * Evict user from cache.
     *
     * @param user
     */
    void evict(RealmModel realm, UserModel user);

    /**
     * Evict users of a specific realm
     *
     * @param realm
     */
    void evict(RealmModel realm);

    /**
     * Clear cache entirely.
     *
     */
    void clear();
}

There are methods for evicting specific users, users contained in a specific realm, or the entire cache.