Regression in handing CombinedResource WEB-INF between Jetty 11 and Jetty 12

[Spikhalskiy]

Jetty version(s)
Jetty 12.0.16 vs Jetty 11.0.24

Jetty Environment
EE 10

Description

We have embedded jetty servers that use a shared resources "layer" packed as a jar.
The setup works as expected in Jetty 11, but an attempt to migrate to Jetty 12 leads to the following exception:

java.lang.NullPointerException: Cannot invoke "java.net.URI.toString()" because the return value of "org.eclipse.jetty.util.resource.Resource.getURI()" is null
	at org.eclipse.jetty.ee10.webapp.JettyWebXmlConfiguration.setupXmlConfiguration(JettyWebXmlConfiguration.java:135) ~[jetty-ee10-webapp-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.ee10.webapp.JettyWebXmlConfiguration.configure(JettyWebXmlConfiguration.java:70) ~[jetty-ee10-webapp-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.ee10.webapp.Configurations.configure(Configurations.java:505) ~[jetty-ee10-webapp-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.ee10.webapp.WebAppContext.configure(WebAppContext.java:484) ~[jetty-ee10-webapp-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.ee10.webapp.WebAppContext.startContext(WebAppContext.java:1300) ~[jetty-ee10-webapp-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.ee10.servlet.ServletContextHandler.lambda$doStart$0(ServletContextHandler.java:1047) ~[jetty-ee10-servlet-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.server.handler.ContextHandler$ScopedContext.call(ContextHandler.java:1452) ~[jetty-server-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.ee10.servlet.ServletContextHandler.doStart(ServletContextHandler.java:1044) ~[jetty-ee10-servlet-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.ee10.webapp.WebAppContext.doStart(WebAppContext.java:503) ~[jetty-ee10-webapp-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:93) ~[jetty-util-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:169) ~[jetty-util-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:120) ~[jetty-util-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.server.Handler$Abstract.doStart(Handler.java:491) ~[jetty-server-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:93) ~[jetty-util-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:169) ~[jetty-util-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.server.Server.start(Server.java:641) ~[jetty-server-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:120) ~[jetty-util-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.server.Handler$Abstract.doStart(Handler.java:491) ~[jetty-server-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.server.Server.doStart(Server.java:582) ~[jetty-server-12.0.16.jar:12.0.16]
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:93) ~[jetty-util-12.0.16.jar:12.0.16]

Looking further into Jetty codebase the exception happens in JettyWebXmlConfiguration:

        props.put(PROPERTY_WEB_INF_URI, XmlConfiguration.normalizeURI(webInf.getURI().toString()));

because webInf is a CombinedResource and getURI returns null for it. Meanwhile, it looks like it's allowed and expected for webInf resource to be a CombinedResource based on the following comment from WebAppContext:

    public Resource getWebInf() throws IOException
    {
        if (getBaseResource() == null)
            return null;

        // Is there a WEB-INF directory anywhere in the Resource Base?
        // ResourceBase could be a CombinedResource
        // The result could be a CombinedResource with multiple WEB-INF directories
        // Can return from WEB-INF/lib/foo.jar!/WEB-INF
        // Can also never return from a META-INF/versions/#/WEB-INF location
        Resource webInf = getBaseResource().resolve("WEB-INF/");
        if (Resources.isReadableDirectory(webInf))
            return webInf;

        return null;
    }

This looks like a regression in a supported scenario from Jetty 11.

[janbartel]

@Spikhalskiy are you relying on the value of the properties that are set in JettyWebXmlConfiguration? If those properties were skipped if WEB-INF was a CombinedResource would that be a problem for you?

[Spikhalskiy]

@janbartel I'm not sure I understand what scope of properties you mean, but the answer is likely yes, we are relying on them. We need at least "contextPath" from jetty-web.xml to get the correct bindings.