How do a give an embedded Tomcat instance a custom classloader when using gradle-Tomcat-Plugin

Question

I'm trying to put Spring's custom Tomcat classloader into my embedded Tomcat instance that I use for integration tests in my Gradle project because I plan on using load time weaving. It works fine in my normal install when I place spring-instrument-tomcat-3.2.5.RELEASE.jar into the apache-tomcat-7.0.40/lib folder, but how do I access that folder of an embedded Tomcat instance and place the jar in there before the boostrap classloader finds it?

https://github.com/bmuschko/gradle-tomcat-plugin/

Before making the suggested change I was getting this error

java.lang.ClassNotFoundException: org.springframework.instrument.classloading.tomcat.TomcatInstrumentableClassLoader

After making the suggested changes I get a new error. Here's my build.gradle with the changes in the build script

apply plugin: 'war'
apply plugin: 'tomcat'

sourceCompatibility = 1.7
version = '1.0'

task wrapper(type: Wrapper) {
    gradleVersion = '1.9'
}

buildscript {
    repositories {
        jcenter()
        mavenCentral()
    }
    dependencies {
        classpath group: 'org.gradle.api.plugins', name:'gradle-tomcat-plugin', version: '1.0'
        classpath group: 'org.springframework', name: 'spring-instrument-tomcat', version: '3.2.5.RELEASE'
    }
}
repositories {
    mavenCentral()
}
dependencies {
    def springVersion = '3.2.5.RELEASE'
    def springSecurityVersion = '3.2.0.RELEASE'
    def jacksonVersion = '2.3.0'
    def hibernateVersion = '4.3.0.Final'
    def tomcatVersion = '7.0.11'

    compile group: 'com.jayway.restassured', name: 'rest-assured', version: '2.1.0'
    testCompile group: 'junit', name: 'junit', version: '4.11'
    providedCompile group: 'javax.servlet', name: 'javax.servlet-api', version: '3.0.1'
    testCompile group: 'org.mockito', name: 'mockito-core', version: '1.9.5'
    testCompile group: 'org.springframework', name:'spring-test', version: springVersion
    compile group: 'javax.mail', name:'mail', version:'1.4.1'
    compile group: 'org.springframework', name: 'spring-context-support', version: springVersion //This is used for sending emails
    compile group: 'org.springframework', name: 'spring-webmvc', version: springVersion
    compile group: 'org.springframework', name: 'spring-orm', version: springVersion
    compile group: 'org.springframework', name: 'spring-aspects', version: springVersion
    compile group: 'org.aspectj', name: 'aspectjrt', version: '1.6.0'
    compile group: 'org.aspectj', name: 'aspectjweaver', version: '1.6.0'
    compile group: 'org.springframework', name: 'spring-aop', version: springVersion
    compile group: 'org.springframework.security', name: 'spring-security-web', version: springSecurityVersion
    compile group: 'org.springframework.security', name: 'spring-security-core', version: springSecurityVersion
    compile group: 'org.springframework.security', name: 'spring-security-config', version: springSecurityVersion
    compile group: 'org.hibernate', name: 'hibernate-core', version: hibernateVersion
    compile group: 'org.hibernate', name: 'hibernate-entitymanager', version: hibernateVersion
    compile group: 'commons-dbcp', name: 'commons-dbcp', version: '1.4'
    compile group: 'log4j', name: 'log4j', version: '1.2.17'
    runtime group: 'com.fasterxml.jackson.core', name: 'jackson-core', version: jacksonVersion
    runtime group: 'com.fasterxml.jackson.core', name: 'jackson-databind', version: jacksonVersion
    runtime group: 'mysql', name:'mysql-connector-java', version: '5.1.26'

    tomcat "org.apache.tomcat.embed:tomcat-embed-core:${tomcatVersion}",
           "org.apache.tomcat.embed:tomcat-embed-logging-juli:${tomcatVersion}"
    tomcat("org.apache.tomcat.embed:tomcat-embed-jasper:${tomcatVersion}") {
        exclude group: 'org.eclipse.jdt.core.compiler', module: 'ecj'
    }
}

test {
    maxParallelForks = 5
    forkEvery = 50
    include '**/test/unit/*.*'
    testLogging {
        events "passed", "skipped", "failed"
    }
}

ext {
    tomcatStopPort = 8092
    tomcatStopKey = 'stopKey'
}

task integrationTomcatRun(type: org.gradle.api.plugins.tomcat.TomcatRunWar) {
    outputFile = file("integration_tomcat.log")
    contextPath = ""
    stopPort = tomcatStopPort
    stopKey = tomcatStopKey
    httpPort = 8090
    httpsPort = 8091
    daemon = true
    doFirst{
        println "Starting embedded Tomcat instance"
    }
}

task integrationTomcatStop(type: org.gradle.api.plugins.tomcat.TomcatStop) {
    stopPort = tomcatStopPort
    stopKey = tomcatStopKey
    doFirst{
        println "Stopping embedded Tomcat instance"
    }
}

task integrationTest(type: Test) {
    include '**/test/integration/*.*'
    dependsOn integrationTomcatRun
    finalizedBy integrationTomcatStop
    testLogging {
        events "passed", "skipped", "failed"
    }
}

And here's the stack trace, and the output from the gradle build. Note the new error message NoClassDefFoundError

:compileJava UP-TO-DATE
:processResources UP-TO-DATE
:classes UP-TO-DATE
:war UP-TO-DATE
:integrationTomcatRun
Starting embedded Tomcat instance
LifecycleException
java.lang.NoClassDefFoundError: org/apache/catalina/loader/WebappClassLoader
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:791)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
        at org.apache.tools.ant.AntClassLoader.findBaseClass(AntClassLoader.java:1385)
        at org.apache.tools.ant.AntClassLoader.loadClass(AntClassLoader.java:1080)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:410)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:410)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:186)
        at org.apache.catalina.loader.WebappLoader.createClassLoader(WebappLoader.java:717)
        at org.apache.catalina.loader.WebappLoader.startInternal(WebappLoader.java:581)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5037)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
        at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1033)
        at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:774)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
        at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1033)
        at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:291)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
        at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
        at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:727)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
        at org.apache.catalina.startup.Tomcat.start(Tomcat.java:305)
        at org.apache.catalina.startup.Tomcat$start.call(Unknown Source)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:42)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:112)
        at org.gradle.api.plugins.tomcat.embedded.Tomcat7xServer.start(Tomcat7xServer.groovy:152)
        at org.gradle.api.plugins.tomcat.embedded.TomcatServer$start.call(Unknown Source)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:42)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:112)
        at org.gradle.api.plugins.tomcat.AbstractTomcatRunTask.startTomcat(AbstractTomcatRunTask.groovy:235)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
        at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:361)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:877)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.callCurrent(PogoMetaClassSite.java:66)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:46)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:133)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:137)
        at org.gradle.api.plugins.tomcat.AbstractTomcatRunTask$_validateConfigurationAndStartTomcat_closure1.doCall(AbstractTomcatRunTask.groovy:121)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
        at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:272)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:877)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.callCurrent(PogoMetaClassSite.java:66)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:46)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:133)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:141)
        at org.gradle.api.plugins.tomcat.AbstractTomcatRunTask$_validateConfigurationAndStartTomcat_closure1.doCall(AbstractTomcatRunTask.groovy)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)
        at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:272)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:877)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:39)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:42)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:112)
        at org.gradle.api.plugins.tomcat.internal.LoggingHandler.withJdkFileLogger(LoggingHandler.groovy:43)
        at org.gradle.api.plugins.tomcat.internal.LoggingHandler$withJdkFileLogger.callStatic(Unknown Source)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallStatic(CallSiteArray.java:50)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callStatic(AbstractCallSite.java:157)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callStatic(AbstractCallSite.java:177)
        at org.gradle.api.plugins.tomcat.AbstractTomcatRunTask.validateConfigurationAndStartTomcat(AbstractTomcatRunTask.groovy:120)
        at org.gradle.api.plugins.tomcat.AbstractTomcatRunTask.start(AbstractTomcatRunTask.groovy:82)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:63)
        at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.doExecute(AnnotationProcessingTaskFactory.java:219)
        at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:212)
        at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:201)
        at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:533)
        at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:516)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:80)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:61)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:46)
        at org.gradle.api.internal.tasks.execution.PostExecutionAnalysisTaskExecuter.execute(PostExecutionAnalysisTaskExecuter.java:35)
        at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.execute(SkipUpToDateTaskExecuter.java:64)
        at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:58)
        at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:42)
        at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:52)
        at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:53)
        at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter.execute(ExecuteAtMostOnceTaskExecuter.java:43)
        at org.gradle.api.internal.AbstractTask.executeWithoutThrowingTaskFailure(AbstractTask.java:289)
        at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.executeTask(AbstractTaskPlanExecutor.java:79)
        at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.processTask(AbstractTaskPlanExecutor.java:63)
        at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.run(AbstractTaskPlanExecutor.java:51)
        at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor$1.run(DefaultTaskPlanExecutor.java:33)
        at org.gradle.internal.Factories$1.create(Factories.java:22)
        at org.gradle.cache.internal.DefaultCacheAccess.longRunningOperation(DefaultCacheAccess.java:198)
        at org.gradle.cache.internal.DefaultCacheAccess.longRunningOperation(DefaultCacheAccess.java:266)
        at org.gradle.cache.internal.DefaultPersistentDirectoryStore.longRunningOperation(DefaultPersistentDirectoryStore.java:135)
        at org.gradle.api.internal.changedetection.state.DefaultTaskArtifactStateCacheAccess.longRunningOperation(DefaultTaskArtifactStateCacheAccess.java:95)
        at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor.process(DefaultTaskPlanExecutor.java:31)
        at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter.execute(DefaultTaskGraphExecuter.java:86)
        at org.gradle.execution.SelectedTaskExecutionAction.execute(SelectedTaskExecutionAction.java:29)
        at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:61)
        at org.gradle.execution.DefaultBuildExecuter.access$200(DefaultBuildExecuter.java:23)
        at org.gradle.execution.DefaultBuildExecuter$2.proceed(DefaultBuildExecuter.java:67)
        at org.gradle.execution.DryRunBuildExecutionAction.execute(DryRunBuildExecutionAction.java:32)
        at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:61)
        at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:54)
        at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:166)
        at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradleLauncher.java:113)
        at org.gradle.initialization.DefaultGradleLauncher.run(DefaultGradleLauncher.java:81)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter$DefaultBuildController.run(InProcessBuildActionExecuter.java:64)
        at org.gradle.launcher.cli.ExecuteBuildAction.run(ExecuteBuildAction.java:33)
        at org.gradle.launcher.cli.ExecuteBuildAction.run(ExecuteBuildAction.java:24)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:35)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:26)
        at org.gradle.launcher.cli.RunBuildAction.run(RunBuildAction.java:50)
        at org.gradle.internal.Actions$RunnableActionAdapter.execute(Actions.java:171)
        at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActionFactory.java:201)
        at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActionFactory.java:174)
        at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory.java:170)
        at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory.java:139)
        at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionReportingAction.java:33)
        at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionReportingAction.java:22)
        at org.gradle.launcher.Main.doAction(Main.java:46)
        at org.gradle.launcher.bootstrap.EntryPoint.run(EntryPoint.java:45)
        at org.gradle.launcher.Main.main(Main.java:37)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.gradle.launcher.bootstrap.ProcessBootstrap.runNoExit(ProcessBootstrap.java:50)
        at org.gradle.launcher.bootstrap.ProcessBootstrap.run(ProcessBootstrap.java:32)
        at org.gradle.launcher.GradleMain.main(GradleMain.java:23)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.gradle.wrapper.BootstrapMainStarter.start(BootstrapMainStarter.java:30)
        at org.gradle.wrapper.WrapperExecutor.execute(WrapperExecutor.java:127)
        at org.gradle.wrapper.GradleWrapperMain.main(GradleWrapperMain.java:58)
Caused by: java.lang.ClassNotFoundException: org.apache.catalina.loader.WebappClassLoader
        at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
        ... 161 more
:integrationTomcatRun FAILED

Answer 1

Add to your build.gradle

buildscript {
    dependencies {
        classpath files('/tmp/spring-instrument-tomcat-3.2.5.RELEASE.jar')
    }
}

Or

buildscript {
    repositories {
        mavenCentral()
    } 
    dependencies {
        classpath group: 'org.springframework', name: 'spring-instrument-tomcat', version: '3.2.5.RELEASE'
    }
}