Groovy reports that a file doesn't exists when it really is present in the system

Question

Whenever a build of my Jenkins job finishes, I'm sending an email with the results using the Editable Email Notification plugin (a.k.a. Email-ext plugin). Also, if a certain file is present in the system, I'm modifying the default content of the message to notify of the existence of that file.

For that end, I'm using the Pre-send Script field of the plugin.

Test job configuration:

Prepare an environment for the run

Properties Content

LOG="log.txt"

Build stage

Execute shell

#!/bin/bash

touch ${WORKSPACE}/${LOG}
echo "this is just a log" >> ${WORKSPACE}/${LOG}

Post-build Actions

Editable Email Notification

Pre-send Script

File log = new File("${WORKSPACE}/${LOG}");
logger.println(log.text);

---

When executing the build, Jenkins will create the file in the ${WORKSPACE} and fill it (I'm able to print the contents from the terminal in the Jenkins slave).

But when trying to access it from the Email plugin, the exception java.io.FileNotFoundException is raised:

java.io.FileNotFoundException: /home/jenkins/workspace/testJob/log.txt (No such file or directory)
    at java.io.FileInputStream.open(Native Method)
    at java.io.FileInputStream.<init>(FileInputStream.java:146)
    at groovy.util.CharsetToolkit.<init>(CharsetToolkit.java:69)
    at org.codehaus.groovy.runtime.DefaultGroovyMethods.newReader(DefaultGroovyMethods.java:16958)
    at org.codehaus.groovy.runtime.DefaultGroovyMethods.getText(DefaultGroovyMethods.java:16006)
    at org.codehaus.groovy.runtime.dgm$381.doMethodInvoke(Unknown Source)
    at org.codehaus.groovy.reflection.GeneratedMetaMethod$Proxy.doMethodInvoke(GeneratedMetaMethod.java:70)
    at groovy.lang.MetaClassImpl$GetBeanMethodMetaProperty.getProperty(MetaClassImpl.java:3500)
    at org.codehaus.groovy.runtime.callsite.GetEffectivePojoPropertySite.getProperty(GetEffectivePojoPropertySite.java:61)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callGetProperty(AbstractCallSite.java:227)
    at Script1.run(Script1.groovy:59)
    at groovy.lang.GroovyShell.evaluate(GroovyShell.java:580)
    at groovy.lang.GroovyShell.evaluate(GroovyShell.java:618)
    at groovy.lang.GroovyShell.evaluate(GroovyShell.java:589)
    at hudson.plugins.emailext.ExtendedEmailPublisher.executePresendScript(ExtendedEmailPublisher.java:450)
    at hudson.plugins.emailext.ExtendedEmailPublisher.sendMail(ExtendedEmailPublisher.java:311)
    at hudson.plugins.emailext.ExtendedEmailPublisher._perform(ExtendedEmailPublisher.java:297)
    at hudson.plugins.emailext.ExtendedEmailPublisher.perform(ExtendedEmailPublisher.java:244)
    at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
    at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:782)
    at hudson.model.AbstractBuild$AbstractBuildExecution.performAllBuildSteps(AbstractBuild.java:723)
    at hudson.model.Build$BuildExecution.cleanUp(Build.java:195)
    at hudson.model.Run.execute(Run.java:1785)
    at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
    at hudson.model.ResourceController.execute(ResourceController.java:98)
    at hudson.model.Executor.run(Executor.java:410)

I'm at a loss as why Groovy is complaining about the missing file, whereas if I instead print the path with

logger.println(log.getPath());

it will print it successfully.

NOTE: The logger variable in the Pre-send Script is provided by the notification plugin to access directly the build log.

Answer 1

java.io.File methods will refer to files on the master where Jenkins is running, and not in the current workspace on the slave machine (in case this job indeed runs on a slave machine).

To refer to files on the slave machine, you should use the readFile method

def log = readFile("${WORKSPACE}/${LOG}");

Answer 2

Within a Jenkins pipeline, File log = new File("${WORKSPACE}/${LOG}"); doesn't work.
You can use readFile instead, e.g.:

def log = readFile "${WORKSPACE}/${LOG}"