How to configure the remote discovery with Spring

I'm trying to configure Spring Security SAML 1.0.1 to reach a remote discovery service located at https://discovery.renater.fr/test. Instead, the IDP specified in property defaultIDP of the "CachingMetadataManager" is reached.

In Spring Security SAML 1.0.1 documentation, we can read:

Remote discovery service

In order to enable external IDP discovery service, configure property idpDiscoveryURL in your local SP extended metadata to the external discovery URL. Make sure property idpDiscoveryEnabled is set to true. The remote discovery service needs to support the Identity Provider Discovery Service Protocol and Profile.

Here is how I generate my SP Metadata :

<!-- Filter automatically generates default SP metadata -->
<b:bean id="metadataGeneratorFilter" class="org.springframework.security.saml.metadata.MetadataGeneratorFilter">
    <b:constructor-arg>
        <b:bean class="org.springframework.security.saml.metadata.MetadataGenerator">
            <b:property name="includeDiscoveryExtension" value="true"/>
            <b:property name="extendedMetadata">
                <b:bean class="org.springframework.security.saml.metadata.ExtendedMetadata">
                    <b:property name="idpDiscoveryEnabled" value="true"/>
                    <b:property name="idpDiscoveryURL" value="https://discovery.renater.fr/test"/>
                    <b:property name="idpDiscoveryResponseURL" value="http://acem.u-bretagneloire.fr/ACEM/saml/login/alias/defaultAlias?disco=true"/>
                </b:bean>
            </b:property>
        </b:bean>
    </b:constructor-arg>
</b:bean>

As can be seen, I have set property includeDiscoveryExtension to true in bean MetadataGenerator. I have also set properties idpDiscoveryEnabled, idpDiscoveryURL and idpDiscoveryResponseURL in bean ExtendedMetadata. But when I set the application's log-level to "TRACE", the idpDiscoveryURL value is never displayed.

Question : what is missing in my configuration to reach the discovery URL?

The complete Spring SAML configuration file is :

<?xml version="1.0" encoding="UTF-8" ?>
<b:beans xmlns:b="http://www.springframework.org/schema/beans"
   xmlns="http://www.springframework.org/schema/security"
   xmlns:p="http://www.springframework.org/schema/p"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:context="http://www.springframework.org/schema/context"
   xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
          http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security.xsd
          http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd
          http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

<!-- Enable auto-wiring -->
<context:annotation-config/>

<!-- Scan for auto-wiring classes in spring saml packages -->
<context:component-scan base-package="org.springframework.security.saml"/>

<!-- 
<http security="none" pattern="/favicon.ico"/>
<http security="none" pattern="/images/**"/>
<http security="none" pattern="/css/**"/>
<http security="none" pattern="/logout.jsp"/>
-->
<!-- Security for the administration UI -->
<http pattern="/saml/web/**" use-expressions="false">
    <access-denied-handler error-page="/saml/web/metadata/login"/>
    <form-login login-processing-url="/saml/web/login" login-page="/saml/web/metadata/login" default-target-url="/saml/web/metadata"/>
    <intercept-url pattern="/saml/web/metadata/login" access="IS_AUTHENTICATED_ANONYMOUSLY"/>
    <intercept-url pattern="/saml/web/**" access="ROLE_ADMIN"/>
    <custom-filter before="FIRST" ref="metadataGeneratorFilter"/>
</http>

<!-- Secured pages with SAML as entry point -->
<!-- 
<http entry-point-ref="samlEntryPoint" use-expressions="false">
    <intercept-url pattern="/**" access="IS_AUTHENTICATED_FULLY"/>
    <custom-filter before="FIRST" ref="metadataGeneratorFilter"/>
    <custom-filter after="BASIC_AUTH_FILTER" ref="samlFilter"/>
</http>
-->
<http entry-point-ref="samlEntryPoint"  use-expressions="true" auto-config="true">
    <!-- For Spring Security 4.x, we need to disable csrf, otherwise AJAX requests get 403:-->
    <csrf disabled="true"/>
    <intercept-url access="permitAll" pattern="/" /><!-- To permit "/" allows the use of web.xml's <welcome-file> -->
    <intercept-url access="permitAll" pattern="/home" />
    <intercept-url access="permitAll" pattern="/pages/exceptions/**" />
    <intercept-url access="permitAll" pattern="/javax.faces.resource/**" />
    <intercept-url access="permitAll" pattern="/resources/**" />
    <intercept-url access="hasRole('ROLE_ADMIN')" pattern="/administration/**" />
    <intercept-url access="hasRole('ROLE_ADMIN')" pattern="/rest/**" />
    <intercept-url access="isAuthenticated()" pattern="/**"/><!-- When the user is authentificated by the IDP, but doesn't exist in the application database -->
    <form-login login-page="/login-page-should-not-be-generated-when-using-saml" />
    <logout logout-url="/logout" logout-success-url="/home"/>
    <custom-filter before="FIRST" ref="metadataGeneratorFilter"/>
    <custom-filter after="BASIC_AUTH_FILTER" ref="samlFilter"/>
</http>

<!-- Filters for processing of SAML messages -->
<b:bean id="samlFilter" class="org.springframework.security.web.FilterChainProxy">
    <filter-chain-map request-matcher="ant">
        <filter-chain pattern="/saml/login/**" filters="samlEntryPoint"/>
        <filter-chain pattern="/saml/logout/**" filters="samlLogoutFilter"/>
        <filter-chain pattern="/saml/metadata/**" filters="metadataDisplayFilter"/>
        <filter-chain pattern="/saml/SSO/**" filters="samlWebSSOProcessingFilter"/>
        <filter-chain pattern="/saml/SSOHoK/**" filters="samlWebSSOHoKProcessingFilter"/>
        <filter-chain pattern="/saml/SingleLogout/**" filters="samlLogoutProcessingFilter"/>
        <filter-chain pattern="/saml/discovery/**" filters="samlIDPDiscovery"/>
    </filter-chain-map>
</b:bean>

<!-- Handler deciding where to redirect user after successful login -->
<b:bean id="successRedirectHandler"
      class="org.springframework.security.web.authentication.SavedRequestAwareAuthenticationSuccessHandler">
    <b:property name="defaultTargetUrl" value="/"/>
    <b:property name="alwaysUseDefaultTargetUrl" value="true"/>
</b:bean>
<!--
Use the following for interpreting RelayState coming from unsolicited response as redirect URL:
<b:bean id="successRedirectHandler" class="org.springframework.security.saml.SAMLRelayStateSuccessHandler">
   <b:property name="defaultTargetUrl" value="/" />
</b:bean>
-->

<!-- Handler deciding where to redirect user after failed login -->
<b:bean id="failureRedirectHandler"
      class="org.springframework.security.web.authentication.SimpleUrlAuthenticationFailureHandler">
    <b:property name="useForward" value="true"/>
    <b:property name="defaultFailureUrl" value="/error.jsp"/>
</b:bean>

<!-- Handler for successful logout -->
<b:bean id="successLogoutHandler" class="org.springframework.security.web.authentication.logout.SimpleUrlLogoutSuccessHandler">
    <b:property name="defaultTargetUrl" value="/logout.jsp"/>
</b:bean>

<authentication-manager alias="authenticationManager">
    <!-- Register authentication manager for SAML provider -->
    <authentication-provider ref="authProvider"/>
    <!-- Register authentication manager for administration UI -->
    <authentication-provider>
        <user-service id="adminInterfaceService">
            <user name="admin" password="admin" authorities="ROLE_ADMIN"/>
        </user-service>
    </authentication-provider>
</authentication-manager>

<!-- Logger for SAML messages and events -->
<b:bean id="samlLogger" class="org.springframework.security.saml.log.SAMLDefaultLogger"/>

<!-- Central storage of cryptographic keys -->
<b:bean id="keyManager" class="org.springframework.security.saml.key.JKSKeyManager">
    <b:constructor-arg value="classpath:security/samlKeystore.jks"/>
    <b:constructor-arg type="java.lang.String" value="nalle123"/>
    <b:constructor-arg>
        <b:map>
            <b:entry key="apollo" value="nalle123"/>
        </b:map>
    </b:constructor-arg>
    <b:constructor-arg type="java.lang.String" value="apollo"/>
</b:bean>

<!-- Entry point to initialize authentication, default values taken from properties file -->
<b:bean id="samlEntryPoint" class="org.springframework.security.saml.SAMLEntryPoint">
    <b:property name="defaultProfileOptions">
        <b:bean class="org.springframework.security.saml.websso.WebSSOProfileOptions">
            <b:property name="includeScoping" value="false"/>
        </b:bean>
    </b:property>
</b:bean>

<!-- IDP Discovery Service -->
<b:bean id="samlIDPDiscovery" class="org.springframework.security.saml.SAMLDiscovery">
    <b:property name="idpSelectionPath" value="/WEB-INF/security/idpSelection.jsp"/>
</b:bean>

<!-- Filter automatically generates default SP metadata -->
<b:bean id="metadataGeneratorFilter" class="org.springframework.security.saml.metadata.MetadataGeneratorFilter">
    <b:constructor-arg>
        <b:bean class="org.springframework.security.saml.metadata.MetadataGenerator">
            <b:property name="includeDiscoveryExtension" value="true"/>
            <b:property name="extendedMetadata">
                <b:bean class="org.springframework.security.saml.metadata.ExtendedMetadata">
                    <b:property name="idpDiscoveryEnabled" value="true"/>
                    <b:property name="idpDiscoveryURL" value="https://discovery.renater.fr/test"/>
                    <b:property name="idpDiscoveryResponseURL" value="http://acem.u-bretagneloire.fr/ACEM/saml/login/alias/defaultAlias?disco=true"/>
                </b:bean>
            </b:property>
        </b:bean>
    </b:constructor-arg>
</b:bean>

<!-- The filter is waiting for connections on URL suffixed with filterSuffix and presents SP metadata there -->
<b:bean id="metadataDisplayFilter" class="org.springframework.security.saml.metadata.MetadataDisplayFilter"/>

<!-- Configure HTTP Client to accept certificates from the keystore for HTTPS verification -->
<!--
<b:bean class="org.springframework.security.saml.trust.httpclient.TLSProtocolConfigurer">
    <b:property name="sslHostnameVerification" value="default"/>
</b:bean>
-->

<!-- IDP Metadata configuration - paths to metadata of IDPs in circle of 
    trust is here -->
<b:bean id="metadata"
    class="org.springframework.security.saml.metadata.CachingMetadataManager">
    <b:constructor-arg>
        <b:list>
            <b:bean
                class="org.springframework.security.saml.metadata.ExtendedMetadataDelegate">
                <b:constructor-arg>
                    <b:bean
                        class="org.opensaml.saml2.metadata.provider.HTTPMetadataProvider">
                        <!-- URL containing the metadata -->
                        <b:constructor-arg>
                            <b:value type="java.lang.String">https://federation.renater.fr/test/renater-test-metadata.xml</b:value>
                        </b:constructor-arg>
                        <!-- Timeout for metadata loading in ms -->
                        <b:constructor-arg>
                            <b:value type="int">15000</b:value>
                        </b:constructor-arg>
                        <b:property name="parserPool" ref="parserPool" />
                    </b:bean>
                </b:constructor-arg>
                <b:constructor-arg>
                    <!-- Default extended metadata for entities not specified in the map -->
                    <b:bean
                        class="org.springframework.security.saml.metadata.ExtendedMetadata">
                    </b:bean>
                </b:constructor-arg>
                <b:constructor-arg>
                    <!-- Extended metadata for specific IDPs -->
                    <b:map>
                        <b:entry key="http://idp.ssocircle.com">
                            <b:bean
                                class="org.springframework.security.saml.metadata.ExtendedMetadata" />
                        </b:entry>
                    </b:map>
                </b:constructor-arg>
            </b:bean>
        </b:list>
    </b:constructor-arg>
    <!-- OPTIONAL used when one of the metadata files contains information 
        about this service provider -->
    <!-- <b:property name="hostedSPName" value=""/> -->
    <!-- OPTIONAL property: can tell the system which IDP should be used for 
        authenticating user by default. -->
    <b:property name="defaultIDP" value="https://ident-shib-test.univ-rennes1.fr/idp/shibboleth"/>
</b:bean>

<!--
    NOTE: In a real application you should not use an in memory implementation. You will also want
          to ensure to clean up expired tickets by calling ProxyGrantingTicketStorage.cleanup()
 -->
<b:bean id="pgtStorage" class="org.jasig.cas.client.proxy.ProxyGrantingTicketStorageImpl"/>

<!-- SAML Authentication Provider responsible for validating of received SAML messages -->
<b:bean id="authProvider" class="org.springframework.security.saml.SAMLAuthenticationProvider">
    <!-- OPTIONAL property: can be used to store/load user data after login -->
    <b:property name="userDetails">
        <b:bean class="eu.ueb.acem.services.auth.SamlAuthenticationUserDetailsService"/>
    </b:property>
</b:bean>

<!-- Provider of default SAML Context -->
<b:bean id="contextProvider" class="org.springframework.security.saml.context.SAMLContextProviderImpl"/>

<!-- Processing filter for WebSSO profile messages -->
<b:bean id="samlWebSSOProcessingFilter" class="org.springframework.security.saml.SAMLProcessingFilter">
    <b:property name="authenticationManager" ref="authenticationManager"/>
    <b:property name="authenticationSuccessHandler" ref="successRedirectHandler"/>
    <b:property name="authenticationFailureHandler" ref="failureRedirectHandler"/>
</b:bean>

<!-- Processing filter for WebSSO Holder-of-Key profile -->
<b:bean id="samlWebSSOHoKProcessingFilter" class="org.springframework.security.saml.SAMLWebSSOHoKProcessingFilter">
    <b:property name="authenticationManager" ref="authenticationManager"/>
    <b:property name="authenticationSuccessHandler" ref="successRedirectHandler"/>
    <b:property name="authenticationFailureHandler" ref="failureRedirectHandler"/>
</b:bean>

<!-- Logout handler terminating local session -->
<b:bean id="logoutHandler"
      class="org.springframework.security.web.authentication.logout.SecurityContextLogoutHandler">
    <b:property name="invalidateHttpSession" value="false"/>
</b:bean>

<!-- Override default logout processing filter with the one processing SAML messages -->
<b:bean id="samlLogoutFilter" class="org.springframework.security.saml.SAMLLogoutFilter">
    <b:constructor-arg index="0" ref="successLogoutHandler"/>
    <b:constructor-arg index="1" ref="logoutHandler"/>
    <b:constructor-arg index="2" ref="logoutHandler"/>
</b:bean>

<!-- Filter processing incoming logout messages -->
<!-- First argument determines URL user will be redirected to after successful global logout -->
<b:bean id="samlLogoutProcessingFilter" class="org.springframework.security.saml.SAMLLogoutProcessingFilter">
    <b:constructor-arg index="0" ref="successLogoutHandler"/>
    <b:constructor-arg index="1" ref="logoutHandler"/>
</b:bean>

<!-- Class loading incoming SAML messages from httpRequest stream -->
<b:bean id="processor" class="org.springframework.security.saml.processor.SAMLProcessorImpl">
    <b:constructor-arg>
        <b:list>
            <b:ref bean="redirectBinding"/>
            <b:ref bean="postBinding"/>
            <b:ref bean="artifactBinding"/>
            <b:ref bean="soapBinding"/>
            <b:ref bean="paosBinding"/>
        </b:list>
    </b:constructor-arg>
</b:bean>

<!-- SAML 2.0 WebSSO Assertion Consumer -->
<b:bean id="webSSOprofileConsumer" class="org.springframework.security.saml.websso.WebSSOProfileConsumerImpl"/>

<!-- SAML 2.0 Holder-of-Key WebSSO Assertion Consumer -->
<b:bean id="hokWebSSOprofileConsumer" class="org.springframework.security.saml.websso.WebSSOProfileConsumerHoKImpl"/>

<!-- SAML 2.0 Web SSO profile -->
<b:bean id="webSSOprofile" class="org.springframework.security.saml.websso.WebSSOProfileImpl"/>

<!-- SAML 2.0 Holder-of-Key Web SSO profile -->
<b:bean id="hokWebSSOProfile" class="org.springframework.security.saml.websso.WebSSOProfileConsumerHoKImpl"/>

<!-- SAML 2.0 ECP profile -->
<b:bean id="ecpprofile" class="org.springframework.security.saml.websso.WebSSOProfileECPImpl"/>

<!-- SAML 2.0 Logout Profile -->
<b:bean id="logoutprofile" class="org.springframework.security.saml.websso.SingleLogoutProfileImpl"/>

<!-- Bindings, encoders and decoders used for creating and parsing messages -->
<b:bean id="postBinding" class="org.springframework.security.saml.processor.HTTPPostBinding">
    <b:constructor-arg ref="parserPool"/>
    <b:constructor-arg ref="velocityEngine"/>
</b:bean>

<b:bean id="redirectBinding" class="org.springframework.security.saml.processor.HTTPRedirectDeflateBinding">
    <b:constructor-arg ref="parserPool"/>
</b:bean>

<b:bean id="artifactBinding" class="org.springframework.security.saml.processor.HTTPArtifactBinding">
    <b:constructor-arg ref="parserPool"/>
    <b:constructor-arg ref="velocityEngine"/>
    <b:constructor-arg>
        <b:bean class="org.springframework.security.saml.websso.ArtifactResolutionProfileImpl">
            <b:constructor-arg>
                <b:bean class="org.apache.commons.httpclient.HttpClient">
                    <b:constructor-arg>
                        <b:bean class="org.apache.commons.httpclient.MultiThreadedHttpConnectionManager"/>
                    </b:constructor-arg>
                </b:bean>
            </b:constructor-arg>
            <b:property name="processor">
                <b:bean class="org.springframework.security.saml.processor.SAMLProcessorImpl">
                    <b:constructor-arg ref="soapBinding"/>
                </b:bean>
            </b:property>
        </b:bean>
    </b:constructor-arg>
</b:bean>

<b:bean id="soapBinding" class="org.springframework.security.saml.processor.HTTPSOAP11Binding">
    <b:constructor-arg ref="parserPool"/>
</b:bean>

<b:bean id="paosBinding" class="org.springframework.security.saml.processor.HTTPPAOS11Binding">
    <b:constructor-arg ref="parserPool"/>
</b:bean>

<!-- Initialization of OpenSAML library-->
<b:bean class="org.springframework.security.saml.SAMLBootstrap"/>

<!-- Initialization of the velocity engine -->
<b:bean id="velocityEngine" class="org.springframework.security.saml.util.VelocityFactory" factory-method="getEngine"/>

<!-- XML parser pool needed for OpenSAML parsing -->
<b:bean id="parserPool" class="org.opensaml.xml.parse.StaticBasicParserPool" init-method="initialize">
    <b:property name="builderFeatures">
        <b:map>
            <b:entry key="http://apache.org/xml/features/dom/defer-node-expansion" value="false"/>
        </b:map>
    </b:property>
</b:bean>

<b:bean id="parserPoolHolder" class="org.springframework.security.saml.parser.ParserPoolHolder"/>

I finally found out the solution and can reach the Discovery URL (which returns an error but this will be another question).

The explanation to my problem was that the properties :

<b:property name="idpDiscoveryEnabled" value="true"/>
<b:property name="idpDiscoveryURL" value="https://discovery.renater.fr/test"/>

must be set inside the IDP metadata (in the section commented with "Default extended metadata for entities not specified in the map"), and not in the SP metadata as I was doing.

I had to search for the string "idpDiscoveryEnabled" into Spring Security SAML's repository on GitHub to find out what I was doing wrong.

I would kindly suggest Vladimír Schäfer to add more information about this in the documentation of Spring Security SAML. Because Metadata are used both in SP and IDP configurations, it's kind of easy to mix topics and don't realize that we are setting the properties in the wrong bean.

UPDATE : I realize that the documentation is giving possibly wrong information:

Remote discovery service

In order to enable external IDP discovery service, configure property idpDiscoveryURL in your local SP extended metadata to the external discovery URL. Make sure property idpDiscoveryEnabled is set to true. The remote discovery service needs to support the Identity Provider Discovery Service Protocol and Profile.

To my experience, the part in bold font could be wrong.