Class loading issue with plugin

[Jeff Fry]

My plugin uses a 3rd party library that dynamically loads some classes. The exception below occurs from the jelly UI where the library is called to validate a connection. I have all the required jars from the 3rd party library included in the plugins WEB-INF/lib and validated this class file (com.vmware.cis.SessionStub) is in fact there. This feels like a Jenkins class loading quirk. How could I troubleshoot and fix?

java.lang.ClassNotFoundException: com.vmware.cis.SessionStub
	at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
	at org.eclipse.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:560)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
	at com.vmware.vapi.bindings.StubFactory.createStub(StubFactory.java:74)
Caused: java.lang.RuntimeException
	at com.vmware.vapi.bindings.StubFactory.createStub(StubFactory.java:93)
	at hudson.plugins.vmware.authentication.VapiAuthenticationHelper.loginByUsernameAndPassword(VapiAuthenticationHelper.java:69)
	at hudson.plugins.vmware.MachineCenter.testMachineCenterLogin(MachineCenter.java:213)
	at hudson.plugins.vmware.MachineCenterCredential$DescriptorImpl.doValidate(MachineCenterCredential.java:33)
	at java.lang.invoke.MethodHandle.invokeWithArguments(MethodHandle.java:627)
	at org.kohsuke.stapler.Function$MethodFunction.invoke(Function.java:343)
	at org.kohsuke.stapler.Function.bindAndInvoke(Function.java:184)
	at org.kohsuke.stapler.Function.bindAndInvokeAndServeResponse(Function.java:117)
	at org.kohsuke.stapler.MetaClass$1.doDispatch(MetaClass.java:129)
	at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:58)
	at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:715)
	at org.kohsuke.stapler.Stapler.invoke(Stapler.java:845)
	at org.kohsuke.stapler.MetaClass$5.doDispatch(MetaClass.java:248)
	at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:58)
	at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:715)
	at org.kohsuke.stapler.Stapler.invoke(Stapler.java:845)
	at org.kohsuke.stapler.Stapler.invoke(Stapler.java:649)
	at org.kohsuke.stapler.Stapler.service(Stapler.java:238)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
	at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:841)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1650)
	at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:154)
	at com.cloudbees.jenkins.support.impl.cloudbees.UnrestrictedApiCallsMonitor$ApiMonitorFilter.doFilter(UnrestrictedApiCallsMonitor.java:120)
	at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:151)
	at com.cloudbees.jenkins.support.slowrequest.SlowRequestFilter.doFilter(SlowRequestFilter.java:37)
	at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:151)
	at com.cloudbees.opscenter.client.plugin.OfflineSecurityRealmFilter._doFilter(OfflineSecurityRealmFilter.java:95)
	at com.cloudbees.opscenter.client.plugin.OfflineSecurityRealmFilter.doFilter(OfflineSecurityRealmFilter.java:70)
	at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:151)
	at com.cloudbees.opscenter.security.ClusterSessionFilter._doFilter(ClusterSessionFilter.java:69)
	at com.cloudbees.opscenter.security.ClusterSessionFilter.doFilter(ClusterSessionFilter.java:44)
	at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:151)
	at jenkins.metrics.impl.MetricsFilter.doFilter(MetricsFilter.java:125)
	at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:151)
	at hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:157)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
	at hudson.security.csrf.CrumbFilter.doFilter(CrumbFilter.java:99)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
	at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:84)
	at hudson.security.UnwrapSecurityExceptionFilter.doFilter(UnwrapSecurityExceptionFilter.java:51)
	at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
	at jenkins.security.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:117)
	at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
	at org.acegisecurity.providers.anonymous.AnonymousProcessingFilter.doFilter(AnonymousProcessingFilter.java:125)
	at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
	at org.acegisecurity.ui.rememberme.RememberMeProcessingFilter.doFilter(RememberMeProcessingFilter.java:142)
	at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
	at org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:271)
	at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
	at jenkins.security.BasicHeaderProcessor.doFilter(BasicHeaderProcessor.java:93)
	at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
	at org.acegisecurity.context.HttpSessionContextIntegrationFilter.doFilter(HttpSessionContextIntegrationFilter.java:249)
	at hudson.security.HttpSessionContextIntegrationFilter2.doFilter(HttpSessionContextIntegrationFilter2.java:67)
	at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
	at hudson.security.ChainedServletFilter.doFilter(ChainedServletFilter.java:90)
	at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:171)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
	at org.kohsuke.stapler.compression.CompressionFilter.doFilter(CompressionFilter.java:49)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
	at hudson.util.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:82)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
	at org.kohsuke.stapler.DiagnosticThreadNameFilter.doFilter(DiagnosticThreadNameFilter.java:30)
	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637)
	at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:533)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
	at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:524)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:190)
	at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1595)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:188)
	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1253)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:168)
	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:473)
	at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1564)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:166)
	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1155)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
	at org.eclipse.jetty.server.Server.handle(Server.java:564)
	at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:317)
	at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:251)
	at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:279)
	at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:110)
	at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:124)
	at winstone.BoundedExecutorService$1.run(BoundedExecutorService.java:77)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

Managed Master 2.107.3.4-rolling

java.class.path
/usr/share/jenkins/jenkins.war
java.class.version
52.0
java.endorsed.dirs
/usr/lib/jvm/java-1.8-openjdk/jre/lib/endorsed
java.ext.dirs
/usr/lib/jvm/java-1.8-openjdk/jre/lib/ext:/usr/java/packages/lib/ext
java.home
/usr/lib/jvm/java-1.8-openjdk/jre
java.io.tmpdir
/tmp
java.library.path
/usr/lib/jvm/java-1.8-openjdk/jre/lib/amd64/server:/usr/lib/jvm/java-1.8-openjdk/jre/lib/amd64:/usr/lib/jvm/java-1.8-openjdk/jre/../lib/amd64:/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib
java.runtime.name
OpenJDK Runtime Environment
java.runtime.version
1.8.0_121-b13

[Ryan Campbell]

I usually have to toString the URLClassloader to see what paths it is pulling from. Play with it in groovy console to understand why it isn't working as you expect.

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[Jesse Glick]

On Sat, Jul 7, 2018 at 6:42 AM Jeff Fry <jf...@cloudbees.com> wrote:
> This feels like a Jenkins class loading quirk. How could I troubleshoot and fix?

Start by reading

https://jenkins.io/doc/developer/plugin-development/dependencies-and-class-loading/

[Jeff Fry]

I read the dependencies and class loading page and I don't think these 3rd party libraries have this issue. I switched over to debugging with the Jenkins Jetty debug server and I get a slightly different stacktrace below. What I notice now is that JettyAndServletApiOnlyClassLoader (https://github.com/jenkinsci/maven-hpi-plugin/blob/master/src/main/java/org/jenkinsci/maven/plugins/hpi/JettyAndServletApiOnlyClassLoader.java) is being used. This class loader looks to restrict class loading from the web application. My code is being initiated from the Jenkins UI to validate connection parameters. Is that what's going on? Calls from the Jenkins web app cannot dynamically load 3rd party classes?

-------

@Override
	protected Class<?> findClass(String name) throws ClassNotFoundException {
	if (name.startsWith("javax.")
	|| name.startsWith("org.eclipse.jetty."))
	return jettyClassLoader.loadClass(name);
	else
	throw new ClassNotFoundException(name);
	}

------

java.lang.ClassNotFoundException: com.vmware.cis.SessionStub
	at org.jenkinsci.maven.plugins.hpi.JettyAndServletApiOnlyClassLoader.findClass(JettyAndServletApiOnlyClassLoader.java:38)

	at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
	at org.eclipse.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:560)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
	at com.vmware.vapi.bindings.StubFactory.createStub(StubFactory.java:74)
Caused: java.lang.RuntimeException
	at com.vmware.vapi.bindings.StubFactory.createStub(StubFactory.java:93)

	at hudson.plugins.vmware.authentication.VapiAuthenticationHelper.loginByUsernameAndPassword(VapiAuthenticationHelper.java:73)

[Jesse Glick]

Offhand it sounds like you need to call
`Thread.setContextClassLoader`, depending on what exactly that
`StubFactory` is doing. (OSS?)

[John LaBarge]

Did you manage to get passed this?  If so, how did you do it? 

Thanks -