Is it possible to deploy a Krazo app as part of an EAR archive on OpenLiberty?

[mthmulders]

I am building an application that has a Krazo web application as its UI. The web application lives in its own Maven module of type 'war'; there are a few more Maven modules, but I think this is not relevant.

My desired application architecture would be to package the 'war' modules inside an 'ear' and deploy that to OpenLiberty. Ideally, all libraries that are shared between the 'war' and other modules should not be duplicated, so I have the following configuration for the Maven EAR Plugin:

        <configuration>
          <defaultLibBundleDir>lib</defaultLibBundleDir>
          <modules>
            <jarModule>
              <groupId>it.mulders.openliberty.tests</groupId>
              <artifactId>domain</artifactId>
            </jarModule>
            <webModule>
              <groupId>it.mulders.openliberty.tests</groupId>
              <artifactId>web</artifactId>
              <contextRoot>/</contextRoot>
            </webModule>
          </modules>
          <skinnyModules>true</skinnyModules>
        </configuration>

The EAR looks fine, with "skinny" WAR-modules inside and all shared libraries in a 'lib/' directory inside that EAR.

My OpenLiberty 'server.xml' has the following, to prevent OpenLiberty from scanning all libraries that do not contain Jakarta beans:

<cdi enableImplicitBeanArchives="false" />

When I start the application with mvn liberty:dev -pl :<module-that-builds-ear>, I get the following errors:

[INFO] [WARNING ] CWOWB1009W: Implicit bean archives are disabled.
[INFO] [ERROR   ] CWWKZ0106E: Could not start web application openliberty-mvc-ear.
[INFO] [ERROR   ] CWWKZ0002E: An exception occurred while starting the application openliberty-mvc-ear. The exception message was: com.ibm.ws.container.service.state.StateChangeException: org.jboss.weld.exceptions.DeploymentException: WELD-001408: Unsatisfied dependencies for type Models with qualifiers @Default
[INFO]   at injection point [BackedAnnotatedParameter] Parameter 1 of [BackedAnnotatedConstructor] @Inject public it.mulders.openliberty.tests.web.home.HomeController(Models, ServiceInterface)
[INFO]   at it.mulders.openliberty.tests.web.home.HomeController.<init>(HomeController.java:0)

I noticed that Krazo does not ship with beans.xml files, so I tried adding them to Krazo 4.0.1 ('core', 'jersey' and 'resteasy' modules) to see if that would resolve the "Unsatisfied dependencies for type Models" - after all, I have disabled implicit bean archives.

After rebuilding Krazo and rebuilding my application, I get a different error when starting the application:

[INFO] [WARNING ] CWOWB1009W: Implicit bean archives are disabled.
[INFO] [ERROR   ] CWWKZ0106E: Could not start web application openliberty-mvc-ear.
[INFO] [ERROR   ] CWWKZ0002E: An exception occurred while starting the application openliberty-mvc-ear. The exception message was: com.ibm.ws.container.service.state.StateChangeException: org.jboss.weld.exceptions.DeploymentException: WELD-001414: Bean name is ambiguous. Name mvc resolves to beans: [Managed Bean [class org.eclipse.krazo.MvcContextImpl] with qualifiers [@Default @Named @Any], Managed Bean [class org.eclipse.krazo.MvcContextImpl] with qualifiers [@Default @Named @Any]]

It seems that instead of no dependency injection of Krazo beans, I now have a duplicate bean.

If necessary, I can share a simplified project setup, but I hope the above makes enough sense already. In case you need any more logging, or OpenLiberty diagnostic logging (ffdc files), I'm happy to help of course!

[mthmulders]

For reference, the three copies of beans.xml that I've added to Krazo are all identical, and look like this:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://xmlns.jcp.org/xml/ns/javaee"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/beans_2_0.xsd"
       version="2.0" bean-discovery-mode="annotated">
    <trim />
</beans>

[mthmulders]

To rule out the Liberty Maven Plugin, I've downloaded a fresh copy of OpenLiberty 26.0.0.1, created a server with the following server.xml:

<?xml version="1.0" encoding="UTF-8"?>
<server description="krazo">
    <featureManager>
        <feature>jakartaee-10.0</feature>

        <feature>cdi</feature>
        <feature>jsonb</feature>
        <feature>pages</feature>
        <feature>restfulWS</feature>
        <feature>servlet</feature>
        <feature>validation</feature>
    </featureManager>
    
    <httpEndpoint id="defaultHttpEndpoint"
                  httpPort="9080"
                  httpsPort="9443" />
                  
    <application location="/full/path/to/openliberty-mvc-ear.ear"
                 name="openliberty-mvc-ear" />

    <logging traceSpecification="*=audit:org.jboss.weld.context.*=finest"
             isoDateFormat="true" />

    <applicationMonitor dropinsEnabled="false" />
    <webContainer deferServletLoad="false" />
    <cdi enableImplicitBeanArchives="false" />
</server>

It still gives the message about a duplicate bean:

WELD-001414: Bean name is ambiguous. Name mvc resolves to beans: [Managed Bean [class org.eclipse.krazo.MvcContextImpl] with qualifiers [@Default @Named @Any], Managed Bean [class org.eclipse.krazo.MvcContextImpl] with qualifiers [@Default @Named @Any]]

For reference, a minimum reproducer is available on my GitHub.

[mthmulders]

Observations from the investigations as part of OpenLiberty/open-liberty#33940:

• A Krazo-app can work when packaged inside an EAR archive.
• That EAR archive should not be built with the skinny WAR pattern. This is because the Krazo ServletContainerInitializer (being a ServletContainerInitializer) must be placed in a JAR inside the WEB-INF/lib directory of a WAR (or inside WEB-INF/classes, but that's a different scenario).
• Skinny WARs move all libraries from WEB-INF/lib to the EAR archive, which avoids having multiple copies of the same JAR inside an EAR archive. The Servlet spec seems not to recognise this deployment scenario.

[mthmulders]

I've looked for a workaround that allows shipping a Krazo-app inside an EAR that was built with the skinny WAR pattern. This is what I have found.

In a skinny WAR, the Krazo-implementation of the ServletContainerInitializer interface (org.eclipse.krazo.servlet.KrazoContainerInitializer) no longer lives in a JAR inside WEB-INF/lib.

So I have created a subclass of KrazoContainerInitializer and gave it the same annotations (@HandlesTypes({Path.class})).
Then, I created a file src/main/webapp/META-INF/services/jakarta.servlet.ServletContainerInitializer and fill it with the fully qualified name of the above class.

It seems that at least OpenLiberty picks up the initialiser this way and executes it.

[mthmulders]

As explained brilliantly in OpenLiberty/open-liberty#33940 (comment), Krazo only works inside an EAR on Liberty if you do not disable Liberty's implicit bean archives. This is enabled by default, but I had it disabled and then the Krazo JAR files aren't even scanned for beans.