Keycloak can federate external user databases. Out of the box we have support for LDAP and Active Directory. Before you dive into this, you should understand how Keycloak does federation. Keycloak performs federation a bit differently than other products/projects. The vision of Keycloak is that it is an out of the box solution that should provide a core set of feature irregardless of the backend user storage you want to use. Because of this requirement/vision, Keycloak has a set data model that all of its services use. Most of the time when you want to federate an external user store, much of the metadata that would be needed to provide this complete feature set does not exist in that external store. For example your LDAP server may only provide password validation, but not support TOTP or user role mappings. The Keycloak User Federation SPI was written to support these completely variable configurations. The way user federation works is that Keycloak will import your federated users on demand to its local storage. How much metadata that is imported depends on the underlying federation plugin and how that plugin is configured. Some federation plugins may only import the username into Keycloak storage, others might import everything from name, address, and phone number, to user role mappings. Some plugins might want to import credentials directly into Keycloak storage and let Keycloak handle credential validation. Others might want to handle credential validation themselves. The goal of the Federation SPI is to support all of these scenarios.

Keycloak comes with a built-in LDAP/AD plugin. By default, it is set up only to import username, email, first and last name, but you are free to configure mappers and add more attributes or delete default ones. It supports password validation via LDAP/AD protocols and different user metadata synchronization modes. To configure a federated LDAP store go to the admin console. Click on the Users menu option to get you to the user management page. Then click on the Federation submenu option. When you get to this page there is an "Add Provider" select box. You should see "ldap" within this list. Selecting "ldap" will bring you to the ldap configuration page.

Edit mode defines various synchronization options with your LDAP store depending on what privileges you have. READONLY Username, email, first and last name and other mapped attributes will be unchangeable. Keycloak will show an error anytime anybody tries to update these fields. Also, password updates will not be supported. WRITABLE Username, email, first and last name, other mapped attributes and passwords can all be updated and will be synchronized automatically with your LDAP store. UNSYNCED Any changes to username, email, first and last name, and passwords will be stored in Keycloak local storage. It is up to you to figure out how to synchronize back to LDAP.

Display Name Name used when this provider is referenced in the admin console Priority The priority of this provider when looking up users or for adding registrations. Sync Registrations If a new user is added through a registration page or admin console, should the user be eligible to be synchronized to this provider. Allow Kerberos authentication Enable Kerberos/SPNEGO authentication in realm with users data provisioned from LDAP. More info in Kerberos section. Other options The rest of the configuration options should be self explanatory. You can use tooltips in admin console to see some more details about them.

When you configure secured connection URL to LDAP (for example ldaps://myhost.com:636 ) the Keycloak will use SSL for the communication with LDAP server. The important thing is to properly configure truststore on the Keycloak server side, because SSL won't work if Keycloak can't trust the SSL connection with LDAP (Keycloak acts as the client here, when LDAP acts as server). The global truststore for the Keycloak can be configured with Truststore SPI in the keycloak-server.json file and it's described in the details here. If you don't configure truststore SPI, the truststore will fallback to the default mechanism provided by Java (either the file provided by system property javax.net.ssl.trustStore or finally the cacerts file from JDK if even the system property is not set). There is configuration property Use Truststore SPI in the LDAP federation provider configuration, where you can choose whether Truststore SPI is used. By default, the value is ldaps only, which is fine for most of deployments, because attempt to use Truststore SPI is done just if connection to LDAP starts with ldaps .

LDAP Federation Provider will automatically take care of synchronization (import) of needed LDAP users into Keycloak database. For example once you first authenticate LDAP user john from Keycloak UI, LDAP Federation provider will first import this LDAP user into Keycloak database and then authenticate against LDAP password. Federation Provider imports just requested users by default, so if you click to View all users in Keycloak admin console, you will see just those LDAP users, which were already authenticated/requested by Keycloak. If you want to sync all LDAP users into Keycloak database, you may configure and enable Sync, which is in admin console on same page like the configuration of Federation provider itself. There are 2 types of sync: Full sync This will synchronize all LDAP users into Keycloak DB. Those LDAP users, which already exist in Keycloak and were changed in LDAP directly will be updated in Keycloak DB (For example if user Mary Kelly was changed in LDAP to Mary Doe). Changed users sync This will check LDAP and it will sync into Keycloak just those users, which were created or updated in LDAP from the time of last sync. In usual cases you may want to trigger full sync at the beginning, so you will import all LDAP users to Keycloak just once. Then you may setup periodic sync of changed users, so Keycloak will periodically ask LDAP server for newly created or updated users and backport them to Keycloak DB. Also you may want to trigger full sync again after some longer time or setup periodic full sync as well. In admin console, you can trigger sync directly or you can enable periodic changed or full sync.

LDAP mappers are listeners, which are triggered by LDAP Federation provider at various points and provide another extension point to LDAP integration. They are triggered during import LDAP user into Keycloak, registration Keycloak user back to LDAP or when querying LDAP user from Keycloak. When you create LDAP Federation provider, Keycloak will automatically provide set of builtin mappers for this provider. You are free to change this set and create new mapper or update/delete existing ones. By default, we have those implementation of LDAP federation mapper: User Attribute Mapper This allows to specify which LDAP attribute is mapped to which attribute of Keycloak User. So for example you can configure that LDAP attribute mail is supposed to be mapped to the UserModel attribute email in Keycloak database. For this mapper implementation, there is always one-to-one mapping (one LDAP attribute mapped to one Keycloak UserModel attribute) FullName Mapper This allows to specify that fullname of user, which is saved in some LDAP attribute (usualy cn ) will be mapped to firstName and lastname attributes of UserModel. Having cn to contain full name of user is common case for some LDAP deployments. Role Mapper This allows to configure role mappings from LDAP into Keycloak role mappings. One Role mapper can be used to map LDAP roles (usually groups from particular branch of LDAP tree) into roles corresponding to either realm roles or client roles of specified client. It's not a problem to configure more Role mappers for same LDAP provider. So for example you can specify that role mappings from groups under ou=main,dc=example,dc=org will be mapped to realm role mappings and role mappings from groups under ou=finance,dc=example,dc=org will be mapped to client role mappings of client finance . Hardcoded Role Mapper This mapper will grant specified Keycloak role to each Keycloak user linked with LDAP. Group Mapper This allows to configure group mappings from LDAP into Keycloak group mappings. Group mapper can be used to map LDAP groups from particular branch of LDAP tree into groups in Keycloak. And it will also propagate user-group mappings from LDAP into user-group mappings in Keycloak. You can choose to preserve group inheritance from LDAP as well, but this may fail as Keycloak inheritance is more restrictive than LDAP (For example in Keycloak each group can have just one parent and there is no recursion allowed. In LDAP the recursion is possible and every group can be member of more other groups too). As of now, the mapper doesn't provide mapping of LDAP roles-groups to Keycloak roles-groups (For example when LDAP group cn=role1,ou=roles,dc=example,dc=com is member of LDAP group cn=group1,ou=groups,dc=example,dc=com , we don't support the mapping of Keycloak role role1 imported from LDAP to corresponding Keycloak group group1 imported from LDAP). MSAD User Account Mapper Mapper specific to Microsoft Active Directory (MSAD). It's able to tightly integrate the MSAD user account state into Keycloak account state (account enabled, password is expired etc). It's using userAccountControl and pwdLastSet LDAP attributes for that (both are specific to MSAD and are not LDAP standard). For example if pwdLastSet is 0, the Keycloak user is required to update password (there will be UPDATE_PASSWORD required action added to him in Keycloak). Or if userAccountControl is 514 (disabled account) the Keycloak user is disabled as well etc. For writable LDAP, the mapping is bi-directional and the state from Keycloak is propagated to LDAP (For example enable user in Keycloak admin console will update the value of userAccountControl in MSAD and effectively enable him in MSAD as well). For writable LDAPs, mapper also provides mapping of error codes during MSAD user authentication to the appropriate action in Keycloak. For example if MSAD user authentication fails due to the fact, that MSAD password is expired, the mapper will allow user to authenticate into Keycloak, but it will add UPDATE_PASSWORD required action to the user, so user must update his password. By default, there is set of User Attribute mappers to map basic UserModel attributes username, first name, lastname and email to corresponding LDAP attributes. You are free to extend this and provide more attribute mappings (For example to street, postalCode etc), delete firstName/lastname mapper and put fullName mapper instead, add role mappers etc. Admin console provides tooltips, which should help on how to configure corresponding mappers. We have an example, which is showing LDAP integration and set of base mappers and sample mappers (mappers for street and postalCode) . It's in examples/ldap in the Keycloak example distribution or demo distribution download. You can also check the example sources directly here .

The keycloak examples directory contains an example of a simple User Federation Provider backed by a simple properties file. See examples/providers/federation-provider. Most of how to create a federation provider is explained directly within the example code, but some information is here too. Writing a User Federation Provider starts by implementing the UserFederationProvider and UserFederationProviderFactory interfaces. Please see the Javadoc and example for complete details on how to do this. Some important methods of note: getUserByUsername() and getUserByEmail() require that you query your federated storage and if the user exists create and import the user into Keycloak storage. How much metadata you import is fully up to you. This import is done by invoking methods on the object returned KeycloakSession.userStorage() to add and import user information. The proxy() method will be called whenever Keycloak has found an imported UserModel. This allows the federation provider to proxy the UserModel which is useful if you want to support external storage updates on demand. After your code is written you must package up all your classes within a JAR file. This jar file must contain a file called org.keycloak.models.UserFederationProviderFactory within the META-INF/services directory of the JAR. This file is a list of fully qualified classnames of all implementations of UserFederationProviderFactory. For more details on writing provider implementations and how to deploy to Keycloak refer to the providers section.