Integrating AppFuse - a Crowd-Acegi Integration Tutorial

AppFuse provides a sweet starting point for developing web applications. You choose the frameworks, AppFuse generates the skeleton application.

At its core, the web security of AppFuse 2.0.1 and earlier applications relies on the modular and extensible Acegi authentication framework. In this tutorial, we look at a basic integration of Crowd with Acegi, using an application generated by AppFuse.

If you're working with AppFuse 2.0.2 or later, it uses Spring Security instead of Acegi. Please see our separate tutorial.

This tutorial assumes you have installed Crowd 1.5.1 or later.

Step 1. Get AppFuse

In this tutorial, we will be using the Struts2-basic archetype to create the project, but the other types should be similar. For more information, consult the AppFuse quickstart guide. In particular, it outlines the database requirements for AppFuse.

Create the project.

mvn archetype:create -DarchetypeGroupId=org.appfuse.archetypes \
-DarchetypeArtifactId=appfuse-basic-struts \
-DremoteRepositories=http://static.appfuse.org/releases -DarchetypeVersion=2.0 \
-DgroupId=com.mycompany.app -DartifactId=myproject

Since we will be editing the core Acegi configuration, we will need the full source code of the application.
```
cd myproject
mvn appfuse:full-source
```
Build it.
```
mvn clean install
```
Run it.
```
mvn jetty:run-war -Dmaven.test.skip
```
Play with it.
```
http://localhost:8080/
```
Shut it down.
```
ctrl+c
```

Step 2. Let Crowd Know about AppFuse

Add appfuse as an application via the Crowd Console. See Adding an Application for more information.

Step 3. Add the Crowd Acegi Connector to AppFuse

Open up the pom.xml and add the Crowd client libraries as a project dependency:

<dependencies>
  <dependency>
    <groupId>com.atlassian.crowd</groupId>
    <artifactId>crowd-integration-client</artifactId>
    <version>1.5.1</version>
  </dependency>
...
</dependencies>

You will also need to create the file myproject/src/main/resources/crowd.properties:

application.name                        appfuse
application.password                    password
application.login.url                   http://localhost:8095/crowd/
crowd.server.url                        http://localhost:8095/crowd/services/
session.isauthenticated                 session.isauthenticated
session.tokenkey                        session.tokenkey
session.validationinterval              0
session.lastvalidation                  session.lastvalidation

In particular, the application name and password must match the values defined for the application added in Step 2.

Finally, copy the STANDALONE/client/conf/crowd-ehcache.xml to myproject/src/main/resources/crowd-ehcache.xml. This file defines the cache properties, such as cache timeouts, used when accessing data from the Crowd server.

Step 4. Hook Up Centralised Authentication

Before modifying the security configuration, you will need to add the Spring configuration file to wire up the Crowd client beans. Add the applicationContext-CrowdClient.xml configuration file to the list of contextConfigLocations in WEB-INF/web.xml:

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>
        classpath:/applicationContext-resources.xml
        classpath:/applicationContext-dao.xml
        classpath:/applicationContext-service.xml
        classpath*:/applicationContext.xml
        classpath:/applicationContext-CrowdClient.xml
        /WEB-INF/applicationContext*.xml
        /WEB-INF/xfire-servlet.xml
        /WEB-INF/security.xml
    </param-value>
</context-param>

AppFuse neatly stores all the Acegi configuration in myproject/src/main/webapp/WEB-INF/security.xml. In order to get centralised authentication, we will need to set up Acegi to use the wrapped authenticator class we just created. Edit the Acegi beans in security.xml:

Add the definition of the CrowdUserDetailsService:

<bean id="crowdUserDetailsService" class="com.atlassian.crowd.integration.acegi.user.CrowdUserDetailsServiceImpl">
        <property name="authenticationManager" ref="crowdAuthenticationManager"/>
        <property name="groupMembershipManager" ref="crowdGroupMembershipManager"/>
        <property name="userManager" ref="crowdUserManager"/>
        <property name="authorityPrefix" value="ROLE_"/>
</bean>

Add the definition of the RemoteCrowdAuthenticationProvider which will delegate Acegi's authentication requests to Crowd:

<bean id="crowdAuthenticationProvider" class="com.atlassian.crowd.integration.acegi.RemoteCrowdAuthenticationProvider">
        <constructor-arg ref="crowdAuthenticationManager"/>
        <constructor-arg ref="httpAuthenticator"/>
        <constructor-arg ref="crowdUserDetailsService"/>
</bean>

Replace the DaoAuthenticationProvider with our authenticator in the authentication manager:

<bean id="authenticationManager" class="org.acegisecurity.providers.ProviderManager">
    <property name="providers">
        <list>
            <ref local="crowdAuthenticationProvider"/>
            <!--ref local="daoAuthenticationProvider"-->
            <ref local="anonymousAuthenticationProvider"/>
            <ref local="rememberMeAuthenticationProvider"/>
        </list>
    </property>
</bean>

Now do a:
```
mvn jetty:run-war -Dmaven.test.skip
```
Head over to http://localhost:8080/.
You should now be able to authenticate the users in your Crowd repository that meet all of the following conditions:

They are in a Crowd directory assigned to the AppFuse application in Crowd. See more information.
They are in Crowd groups named USER and ADMIN. You will need to add these groups and assign the user as a member of the groups. These Crowd group names map to the Acegi authorisation roles defined in the AppFuse application.
They are allowed to authenticate with the AppFuse application because EITHER they are in a group allowed to authenticate with Crowd see more OR their container directory allows all users to authenticate see more.

Congratulations. You have centralised authentication

Application-level centralised user management

One quirk you may notice is that you can't view the profile details of users who exist in Crowd, but did not exist in AppFuse prior to the Crowd integration. Although it's possible to authenticate a Crowd user 'dude' and still run AppFuse as 'dude', 'dude' will not be in AppFuse's local database. AppFuse makes use of a database-backed user management system. In order to achieve application-level centralised user management, AppFuse will need to delegate its calls to create, retrieve, update and delete users to Crowd via Crowd's remote API. This will prevent data redundancy and eliminate the hassle of data synchronisation. This is beyond the scope of this short tutorial.

Step 5. Hook Up Single Sign-On

Enabling single sign-on (SSO) requires a little more tweaking of the security.xml:

Change the default processing filter to Crowd's SSO filter:

<bean id="authenticationProcessingFilter" class="com.atlassian.crowd.integration.acegi.CrowdSSOAuthenticationProcessingFilter">
    <property name="httpAuthenticator" ref="httpAuthenticator"/>
    <property name="authenticationManager" ref="authenticationManager"/>
    <property name="authenticationFailureUrl" value="/login.jsp?error=true"/>
    <property name="defaultTargetUrl" value="/"/>
    <property name="filterProcessesUrl" value="/j_security_check"/>
    <property name="rememberMeServices" ref="rememberMeServices"/>
</bean>

Add the definition of the CrowdLogoutHandler:

<bean id="crowdLogoutHandler" class="com.atlassian.crowd.integration.acegi.CrowdLogoutHandler">
    <property name="httpAuthenticator" ref="httpAuthenticator"/>
</bean>

Update the definition of the LogoutFilter to use the CrowdLogoutHandler. You may need to uncomment the logout filter.

<bean id="logoutFilter" class="org.acegisecurity.ui.logout.LogoutFilter">
    <constructor-arg value="/index.jsp"/>
    <constructor-arg>
        <list>
            <ref bean="rememberMeServices"/>
            <ref bean="crowdLogoutHandler"/>
            <bean class="org.acegisecurity.ui.logout.SecurityContextLogoutHandler"/>
        </list>
    </constructor-arg>
    <property name="filterProcessesUrl" value="/logout.jsp"/>
</bean>

If the logout filter is not defined in the filter invocation list, you will need to add it:

<bean id="filterChainProxy" class="org.acegisecurity.util.FilterChainProxy">
    <property name="filterInvocationDefinitionSource">
        <value>
           ...
           /**=httpSessionContextIntegrationFilter,logoutFilter,authenticationProcessingFilter,securityContextHolderAwareRequestFilter,rememberMeProcessingFilter,anonymousProcessingFilter,exceptionTranslationFilter,filterInvocationInterceptor
        </value>
    ...

Now repeat:

mvn jetty:run-war -Dmaven.test.skip=true

SSO will only work for users that are able to authenticate with both appplications and are authorised to use both applications. Try out the following:

Log in to Crowd – you should be logged in to AppFuse.
Log out of AppFuse – you should be logged out of Crowd.
Log in to AppFuse; log out of Crowd; log in to Crowd as another user; refresh AppFuse – you should be logged in as the new user.

Congratulations, you have SSO

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