keycloak-scim/docbook/reference/en/en-US/modules/jaas.xml

<section id="jaas-adapter">
    <title>JAAS plugin</title>
    <para>
        It's generally not needed to use JAAS for most of the applications, especially if they are HTTP based, but directly choose one of our adapters.
        However some applications and systems may still rely on pure legacy JAAS solution. Keycloak provides couple of login modules
        to help with such use cases. Some login modules provided by Keycloak are:
    </para>
    <para>
        <variablelist>
            <varlistentry>
                <term>org.keycloak.adapters.jaas.DirectAccessGrantsLoginModule</term>
                <listitem>
                    <para>
                        This login module allows to authenticate with username/password from Keycloak database. It's using
                        <link linkend="direct-access-grants">Direct Access Grants</link> Keycloak endpoint to validate on Keycloak side if provided username/password is valid.
                        It's useful especially for non-web based systems, which need to rely on JAAS and want to use Keycloak credentials, but can't use classic browser based
                        authentication flow due to their non-web nature. Example of such application could be messaging application or SSH system.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term>org.keycloak.adapters.jaas.BearerTokenLoginModule</term>
                <listitem>
                    <para>
                        This login module allows to authenticate with Keycloak access token passed to it through CallbackHandler as password.
                        It may be useful for example in case, when you have Keycloak access token from classic web based authentication flow
                        and your web application then needs to talk to external non-web based system, which rely on JAAS. For example to JMS/messaging system.
                    </para>
                </listitem>
            </varlistentry>
        </variablelist>
    </para>
    <para>
        Both login modules have configuration property <literal>keycloak-config-file</literal> where you need to provide location of keycloak.json configuration file.
        It could be either provided from filesystem or from classpath (in that case you may need value like <literal>classpath:/folder-on-classpath/keycloak.json</literal> ).
    </para>
    <para>
        Second property <literal>role-principal-class</literal> allows to specify alternative class for Role principals attached to JAAS Subject. Default
        value for Role principal is <literal>org.keycloak.adapters.jaas.RolePrincipal</literal> . Note that class should have constructor
        with single String argument.
    </para>
</section>