Augmenting External Storage

The PropertyProfileUserStorageProvider example is really limited. While we will be able to login with users stored in a property file, we won’t be able to do much else. If users loaded by this provider need special role or group mappings to fully access particular applications there is no way for us to add additional role mappings to these users. You also can’t modify or add additional important attributes like email, first and last name.

For these types of situations, Keycloak allows you to augment your external store by storing extra information in Keycloak’s database. This is called federated user storage and is encapsulated within the class.


public interface UserFederatedStorageProvider extends Provider {

    Set<GroupModel> getGroups(RealmModel realm, String userId);
    void joinGroup(RealmModel realm, String userId, GroupModel group);
    void leaveGroup(RealmModel realm, String userId, GroupModel group);
    List<String> getMembership(RealmModel realm, GroupModel group, int firstResult, int max);


The UserFederatedStorageProvider instance is available on the KeycloakSession.userFederatedStorage() method. It has all different kinds of methods for storing attributes, group and role mappings, different credential types, and required actions. If your external store’s datamodel cannot support the full Keycloak feature set, then this service can fill in the gaps.

Keycloak comes with a helper class that will delegate every single UserModel method except get/set of username to user federated storage. Override the methods you need to override to delegate to your external storage representations. It is strongly suggested you read the javadoc of this class as it has smaller protected methods you may want to override. Specifically surrounding group membership and role mappings.

Augmentation Example

In our PropertyFileUserStorageProvider example, we just need a simple change to our provider to use the AbstractUserAdapterFederatedStorage.

    protected UserModel createAdapter(RealmModel realm, String username) {
        return new AbstractUserAdapterFederatedStorage(session, realm, model) {
            public String getUsername() {
                return username;

            public void setUsername(String username) {
                String pw = (String)properties.remove(username);
                if (pw != null) {
                    properties.put(username, pw);

We instead define an anonymous class implementation of AbstractUserAdapterFederatedStorage. The setUsername() method makes changes to the properties file and saves it.