Jenkins CI Pipeline Scripts not permitted to use method groovy.lang.GroovyObject

I am Using Jenkins 2 for compiling Java Projects, I want to read the version from a pom.xml, I was following this example:

https://github.com/jenkinsci/pipeline-plugin/blob/master/TUTORIAL.md

The example suggest:

It seems that there is some security problem accessing the File System but I can't figure out what it is giving (or why) that problem:

I am just doing a little bit different than the example:

def version() {
    String path = pwd();
    def matcher = readFile("${path}/pom.xml") =~ '<version>(.+)</version>'
    return matcher ? matcher[0][1] : null
}

The Error I am getting when running the 'version' method :

org.jenkinsci.plugins.scriptsecurity.sandbox.RejectedAccessException: Scripts not permitted to use method groovy.lang.GroovyObject invokeMethod java.lang.String java.lang.Object (org.codehaus.groovy.runtime.GStringImpl call org.codehaus.groovy.runtime.GStringImpl)
    at org.jenkinsci.plugins.scriptsecurity.sandbox.whitelists.StaticWhitelist.rejectMethod(StaticWhitelist.java:165)
    at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SandboxInterceptor.onMethodCall(SandboxInterceptor.java:117)
    at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SandboxInterceptor.onMethodCall(SandboxInterceptor.java:103)
    at org.kohsuke.groovy.sandbox.impl.Checker$1.call(Checker.java:149)
    at org.kohsuke.groovy.sandbox.impl.Checker.checkedCall(Checker.java:146)
    at com.cloudbees.groovy.cps.sandbox.SandboxInvoker.methodCall(SandboxInvoker.java:15)
    at WorkflowScript.run(WorkflowScript:71)
    at ___cps.transform___(Native Method)
    at com.cloudbees.groovy.cps.impl.ContinuationGroup.methodCall(ContinuationGroup.java:55)
    at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.dispatchOrArg(FunctionCallBlock.java:106)
    at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.fixArg(FunctionCallBlock.java:79)
    at sun.reflect.GeneratedMethodAccessor408.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at com.cloudbees.groovy.cps.impl.ContinuationPtr$ContinuationImpl.receive(ContinuationPtr.java:72)
    at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.dispatchOrArg(FunctionCallBlock.java:100)
    at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.fixArg(FunctionCallBlock.java:79)
    at sun.reflect.GeneratedMethodAccessor408.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at com.cloudbees.groovy.cps.impl.ContinuationPtr$ContinuationImpl.receive(ContinuationPtr.java:72)
    at com.cloudbees.groovy.cps.impl.ContinuationGroup.methodCall(ContinuationGroup.java:57)
    at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.dispatchOrArg(FunctionCallBlock.java:106)
    at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.fixArg(FunctionCallBlock.java:79)
    at sun.reflect.GeneratedMethodAccessor408.invoke(Unknown Source)

I am using these versions: Plugin Pipeline 2.1 Jenkins 2.2

Quickfix Solution:

I had similar issue and I resolved it doing the following

1. Navigate to jenkins > Manage jenkins > In-process Script Approval
2. There was a pending command, which I had to approve.

---

Alternative 1: Disable sandbox

As this article explains in depth, groovy scripts are run in sandbox mode by default. This means that a subset of groovy methods are allowed to run without administrator approval. It's also possible to run scripts not in sandbox mode, which implies that the whole script needs to be approved by an administrator at once. This preventing users from approving each line at the time.

Running scripts without sandbox can be done by unchecking this checkbox in your project config just below your script:

Alternative 2: Disable script security

As this article explains it also possible to disable script security completely. First install the permissive script security plugin and after that change your jenkins.xml file add this argument:

-Dpermissive-script-security.enabled=true

So you jenkins.xml will look something like this:

<executable>..bin\java</executable>
<arguments>-Dpermissive-script-security.enabled=true -Xrs -Xmx4096m -Dhudson.lifecycle=hudson.lifecycle.WindowsServiceLifecycle -jar "%BASE%\jenkins.war" --httpPort=80 --webroot="%BASE%\war"</arguments>

Make sure you know what you are doing if you implement this!