Jenkins Pipeline: How to dump errors?

Question

When trying to print errors (e.getMessage()) or dump a stack trace in my Pipeline script, I get an error saying that's not allowed. How can you output the error to the log in this scenario?

try {
    deleteJob( JOB_NAME )
} catch (e) {
    emailError(e.getMessage())
    echo e.getMessage()
}

Without getting this:

org.jenkinsci.plugins.scriptsecurity.sandbox.RejectedAccessException: Scripts not permitted to use method java.lang.Throwable getMessage
    at org.jenkinsci.plugins.scriptsecurity.sandbox.whitelists.StaticWhitelist.rejectMethod(StaticWhitelist.java:158)
    at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SandboxInterceptor.onMethodCall(SandboxInterceptor.java:80)
    at org.kohsuke.groovy.sandbox.impl.Checker$1.call(Checker.java:149)
    at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:146)
    at com.cloudbees.groovy.cps.sandbox.SandboxInvoker.methodCall(SandboxInvoker.java:15)
    at WorkflowScript.runTests(WorkflowScript:325)
    at WorkflowScript.run(WorkflowScript:97)
    at ___cps.transform___(Native Method)
    at com.cloudbees.groovy.cps.impl.ContinuationGroup.methodCall(ContinuationGroup.java:55)
    at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.dispatchOrArg(FunctionCallBlock.java:106)
    at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.fixName(FunctionCallBlock.java:74)
    at sun.reflect.GeneratedMethodAccessor315.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.cloudbees.groovy.cps.impl.ContinuationPtr$ContinuationImpl.receive(ContinuationPtr.java:72)
    at com.cloudbees.groovy.cps.impl.ConstantBlock.eval(ConstantBlock.java:21)
    at com.cloudbees.groovy.cps.Next.step(Next.java:58)
    at com.cloudbees.groovy.cps.Continuable.run0(Continuable.java:154)
    at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.access$001(SandboxContinuable.java:19)
    at org.jenkinsci.plugins.workflow.cps.SandboxContinuable$1.call(SandboxContinuable.java:33)
    at org.jenkinsci.plugins.workflow.cps.SandboxContinuable$1.call(SandboxContinuable.java:30)
    at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.GroovySandbox.runInSandbox(GroovySandbox.java:106)
    at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.run0(SandboxContinuable.java:30)
    at org.jenkinsci.plugins.workflow.cps.CpsThread.runNextChunk(CpsThread.java:164)
    at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.run(CpsThreadGroup.java:277)
    at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.access$000(CpsThreadGroup.java:77)
    at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:186)
    at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:184)
    at org.jenkinsci.plugins.workflow.cps.CpsVmExecutorService$2.call(CpsVmExecutorService.java:47)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at hudson.remoting.SingleLaneExecutorService$1.run(SingleLaneExecutorService.java:112)
    at jenkins.util.ContextResettingExecutorService$1.run(ContextResettingExecutorService.java:28)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    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)
Finished: FAILURE

Answer 1

Call signatures are whitelisted directly in the Jenkins GUI. Go to the script approval management page in Jenkins. Usually that's /scriptApproval/.

You should see that your attempt to use the non-whitelisted method will have created a "pending signature approval". Click the approval button beside the method java.lang.Throwable getMessage entry.

Answer 2

I use following to print the stacktrace to jenkins console:

} catch (exception) {
    echo getStackTrace(exception)
    // needed to explicitly set the result to fail:
    currentBuild.result = 'FAILURE'
    // next only reports an "ERROR: ..." line at the end of the console output
    error exception.getMessage()
}

def String getStackTrace(Throwable aThrowable)
{
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    PrintStream ps = new PrintStream(baos, true);
    aThrowable.printStackTrace(ps);
    return baos.toString();
}

Answer 3

Following code doesn't require exception script approval from Jenkins admin but can be used to print stack-trace on build logs

   catch (exc) {
      def sw = new StringWriter()
      def pw = new PrintWriter(sw)
      exc.printStackTrace(pw)
      echo sw.toString()
   }

Borrowed the idea from https://issues.jenkins.io/browse/JENKINS-44808?focusedCommentId=302635&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-302635