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<chapter id="client-registration">
    <title>Client Registration</title>

    <para>
        In order for an application or service to utilize Keycloak it has to register a client in Keycloak. An
        admin can do this through the admin console (or admin REST endpoints), but clients can also register themselves
        through Keycloak's client registration service.
    </para>

    <para>
        The Client Registration Service provides built-in support for Keycloak Client Representations, OpenID Connect
        Client Meta Data and SAML Entity Descriptors. It's also possible to plugin custom client registration providers
        if required. The Client Registration Service endpoint is <literal>&lt;KEYCLOAK URL&gt;/realms/&lt;realm&gt;/clients/&lt;provider&gt;</literal>.
    </para>
    <para>
        The built-in supported <literal>providers</literal> are:
        <itemizedlist>
            <listitem><literal>default</literal> Keycloak Representations</listitem>
            <listitem><literal>install</literal> Keycloak Adapter Configuration</listitem>
            <listitem><literal>openid-connect</literal> OpenID Connect Dynamic Client Registration</listitem>
            <listitem><literal>saml2-entity-descriptor</literal> SAML Entity Descriptors</listitem>
        </itemizedlist>
        The following sections will describe how to use the different providers.
    </para>

    <section>
        <title>Authentication</title>
        <para>
            To invoke the Client Registration Services you need a token. The token can be a standard bearer token, a
            initial access token or a registration access token.
        </para>

        <section>
            <title>Bearer Token</title>
            <para>
                The bearertoken can be issued on behalf of a user or a Service Account. The following permissions are required
                to invoke the endpoints (see <link linkend='admin-permissions'>Admin Permissions</link> for more details):
                <itemizedlist>
                    <listitem>
                        <literal>create-client</literal> or <literal>manage-client</literal> - To create clients
                    </listitem>
                    <listitem>
                        <literal>view-client</literal> or <literal>manage-client</literal> - To view clients
                    </listitem>
                    <listitem>
                        <literal>manage-client</literal> - To update or delete clients
                    </listitem>
                </itemizedlist>
                If you are using a regular bearer token to create clients we recommend using a token from on behalf of a
                Service Account with only the <literal>create-client</literal> role. See the
                <link linkend="service-accounts">Service Account</link> section for more details.
            </para>
        </section>

        <section>
            <title>Initial Access Token</title>
            <para>
                The best approach to create new clients is by using initial access tokens. An initial access token can
                only be used to create clients and has a configurable expiration as well as a configurable limit on
                how many clients can be created.
            </para>
            <para>
                An initial access token can be created through the admin console. To create a new initial access token
                first select the realm in the admin console, then click on <literal>Realm Settings</literal> in the menu
                on the left, followed by <literal>Initial Access Tokens</literal> in the tabs displayed in the page.
            </para>
            <para>
                You will now be able to see any existing initial access tokens. If you have access you can delete tokens
                that are no longer required. You can only retrieve the value of the token when you are creating it. To
                create a new token click on <literal>Create</literal>. You can now optionally add how long the token
                should be valid, also how many clients can be created using the token. After you click on <literal>Save</literal>
                the token value is displayed. It is important that you copy/paste this token now as you won't be able
                to retrieve it later. If you forget to copy/paste it, then delete the token and create another one.
                The token value is used as a standard bearer token when invoking the Client Registration Services, by
                adding it to the Authorization header in the request. For example:
<programlisting><![CDATA[
Authorization: bearer eyJhbGciOiJSUzI1NiJ9.eyJqdGkiOiJmMjJmNzQyYy04ZjNlLTQ2M....
]]></programlisting>
            </para>
        </section>

        <section>
            <title>Registration Access Token</title>
            <para>
                When you create a client through the Client Registration Service the response will include a registration
                access token. The registration access token provides access to retrieve the client configuration later, but
                also to update or delete the client. The registration access token is included with the request in the
                same way as a bearer token or initial access token. Registration access tokens are only valid once
                when it's used the response will include a new token.
            </para>
            <para>
                If a client was created outside of the Client Registration Service it won't have a registration access
                token associated with it. You can create one through the admin console. This can also be useful if
                you loose the token for a particular client. To create a new token find the client in the admin console
                and click on <literal>Credentials</literal>. Then click on <literal>Generate registration access token</literal>.
            </para>
        </section>
    </section>

    <section>
        <title>Keycloak Representations</title>
        <para>
            The <literal>default</literal> client registration provider can be used to create, retrieve, update and delete a client. It uses
            Keycloaks Client Representation format which provides support for configuring clients exactly as they can
            be configured through the admin console, including for example configuring protocol mappers.
        </para>
        <para>
            To create a client create a Client Representation (JSON) then do a HTTP POST to:
            <literal>&lt;KEYCLOAK URL&gt;/realms/&lt;realm&gt;/clients/default</literal>. It will return a Client Representation
            that also includes the registration access token. You should save the registration access token somewhere
            if you want to retrieve the config, update or delete the client later.
        </para>
        <para>
            To retrieve the Client Representation then do a HTTP GET to:
            <literal>&lt;KEYCLOAK URL&gt;/realms/&lt;realm&gt;/clients/default/&lt;client id&gt;</literal>. It will also
            return a new registration access token.
        </para>
        <para>
            To update the Client Representation then do a HTTP PUT to with the updated Client Representation to:
            <literal>&lt;KEYCLOAK URL&gt;/realms/&lt;realm&gt;/clients/default/&lt;client id&gt;</literal>. It will also
            return a new registration access token.
        </para>
        <para>
            To delete the Client Representation then do a HTTP DELETE to:
            <literal>&lt;KEYCLOAK URL&gt;/realms/&lt;realm&gt;/clients/default/&lt;client id&gt;</literal>
        </para>
    </section>

    <section>
        <title>Keycloak Adapter Configuration</title>
        <para>
            The <literal>installation</literal> client registration provider can be used to retrieve the adapter configuration
            for a client. In addition to token authentication you can also authenticate with client credentials using
            HTTP basic authentication. To do this include the following header in the request:
<programlisting><![CDATA[
Authorization: basic BASE64(client-id + ':' + client-secret)
]]></programlisting>
        </para>
        <para>
            To retrieve the Adapter Configuration then do a HTTP GET to:
            <literal>&lt;KEYCLOAK URL&gt;//realms/&lt;realm&gt;/clients/installation/&lt;client id&gt;</literal>
        </para>
        <para>
            No authentication is required for public clients. This means that for the JavaScript adapter you can
            load the client configuration directly from Keycloak using the above URL.
        </para>
    </section>

    <section>
        <title>OpenID Connect Dynamic Client Registration</title>
        <para>
            Keycloak implements <ulink url="https://openid.net/specs/openid-connect-registration-1_0.html">OpenID Connect Dynamic Client Registration</ulink>,
            which extends <ulink url="https://tools.ietf.org/html/rfc7591">OAuth 2.0 Dynamic Client Registration Protocol</ulink> and
            <ulink url="https://tools.ietf.org/html/rfc7592">OAuth 2.0 Dynamic Client Registration Management Protocol</ulink>.
        </para>
        <para>
            The endpoint to use these specifications to register clients in Keycloak is:
            <literal>&lt;KEYCLOAK URL&gt;/realms/&lt;realm&gt;/clients/oidc[/&lt;client id&gt;]</literal>.
        </para>
        <para>
            This endpoints can also be found in the OpenID Connect Discovery endpoint for the realm:
            <literal>&lt;KEYCLOAK URL&gt;/realms/&lt;realm&gt;/.well-known/openid-configuration</literal>.
        </para>
    </section>

    <section>
        <title>SAML Entity Descriptors</title>
        <para>
            The SAML Entity Descriptor endpoint only supports using SAML v2 Entity Descriptors to create clients. It
            doesn't support retrieving, updating or deleting clients. For those operations the Keycloak representation
            endpoints should be used. When creating a client a Keycloak Client Representation is returned with details
            about the created client, including a registration access token.
        </para>
        <para>
            To create a client do a HTTP POST with the SAML Entity Descriptor to:
            <literal>&lt;KEYCLOAK URL&gt;/realms/&lt;realm&gt;/clients/saml2-entity-descriptor</literal>.
        </para>
    </section>

    <section>
        <title>Client Registration Java API</title>
        <para>
            The Client Registration Java API makes it easy to use the Client Registration Service using Java. To use
            include the dependency <literal>org.keycloak:keycloak-client-registration-api:&gt;VERSION&lt;</literal> from
            Maven.
        </para>
        <para>
            For full instructions on using the Client Registration refer to the JavaDocs. Below is an example of creating
            a client:
<programlisting><![CDATA[
String initialAccessToken = "eyJhbGciOiJSUzI1NiJ9.eyJqdGkiOiJmMjJmNzQyYy04ZjNlLTQ2M....";

ClientRepresentation client = new ClientRepresentation();
client.setClientId(CLIENT_ID);

ClientRegistration reg = ClientRegistration.create().url("http://keycloak/auth/realms/myrealm/clients").build();
reg.auth(Auth.token(initialAccessToken));

client = reg.create(client);

String registrationAccessToken = client.getRegistrationAccessToken();
]]></programlisting>
        </para>
    </section>

    <!--
    <section>
        <title>Client Registration CLI</title>
        <para>
            TODO
        </para>
    </section>
    -->

</chapter>
