Jenkins timeout/abort exception - jenkins

Question

We have a Jenkins pipeline script that requests approval from the user after all the preparatory steps are complete, before it actually applies the changes.
We want to add a timeout to this step, so that if there is no input from the user then the build is aborted, and are currently working on using this kind of method:
try {
timeout(time: 30, unit: 'SECONDS') {
userInput = input("Apply changes?")
}
} catch(err) {
def user = err.getCauses()[0].getUser()
if (user.toString == 'SYSTEM') { // if it's system it's a timeout
didTimeout = true
echo "Build timed out at approval step"
} else if (userInput == false) { // if not and input is false it's the user
echo "Build aborted by: [${user}]"
}
}
This code is based on examples found here: https://support.cloudbees.com/hc/en-us/articles/226554067-Pipeline-How-to-add-an-input-step-with-timeout-that-continues-if-timeout-is-reached-using-a-default-value and other places online, but I really dislike catching all errors then working out what's caused the exception using err.getCauses()[0].getUser(). I'd rather explicitly catch(TimeoutException) or something like that.
So my question is, what are the actual exceptions that would be thrown by either the approval step timing out or the userInput being false? I haven't been able to find anything in the docs or Jenkins codebase so far about this.

Answer 1

The exception class they are referring to is org.jenkinsci.plugins.workflow.steps.FlowInterruptedException.
Cannot believe that this is an example provided by CloudBeeds.
Most (or probably all?) other exceptions won't even have the getCauses() method which of course would throw another exception then from within the catch block.
Furthermore as you already mentioned it is not a good idea to just catch all exceptions.
Edit:
By the way: Scrolling further down that post - in the comments - there you'll find an example catching a FlowInterruptedException.

Answer 2

Rather old topic, but it helped me, and I've done some more research on it.
As I figured out, FlowInterruptedException's getCauses()[0] has .getUser() only when class of getCauses()[0] is org.jenkinsci.plugins.workflow.support.steps.input.Rejection. It is so only when timeout occured while input was active. But, if timeout occured not in input, getCause()[0] will contain object of another class: org.jenkinsci.plugins.workflow.steps.TimeoutStepExecution$ExceededTimeout (directly mentioning timeout).
So, I end up with this:
def is_interrupted_by_timeout(org.jenkinsci.plugins.workflow.steps.FlowInterruptedException e, Boolean throw_again=true) {
// if cause is not determined, re-throw exception
try {
def cause = e.getCauses()[0]
def cause_class = cause.getClass()
//echo("cause ${cause} class: ${cause_class}")
if( cause_class == org.jenkinsci.plugins.workflow.steps.TimeoutStepExecution$ExceededTimeout ) {
// strong detection
return true
} else if( cause_class == org.jenkinsci.plugins.workflow.support.steps.input.Rejection ) {
// indirect detection
def user = cause.getUser()
if( user.toString().equals('SYSTEM') ) {
return true
} else {
return false
}
}
} catch(org.jenkinsci.plugins.scriptsecurity.sandbox.RejectedAccessException e_access) {
// here, we may deal with situation when restricted methods are not approved:
// show message and Jengins' admin will copy/paste and execute them only once per Jenkins installation.
error('''
To run this job, Jenkins admin needs to approve some Java methods.
There are two possible ways to do this:
1. (better) run this code in Jenkins Console (URL: /script):
import org.jenkinsci.plugins.scriptsecurity.scripts.ScriptApproval;
def scriptApproval = ScriptApproval.get()
scriptApproval.approveSignature('method org.jenkinsci.plugins.workflow.steps.FlowInterruptedException getCauses')
scriptApproval.approveSignature('method org.jenkinsci.plugins.workflow.support.steps.input.Rejection getUser')
scriptApproval.save()
'''.stripIndent())
return null
}
if( throw_again ) {
throw e
} else {
return null
}
}
And now, you may catch it with something like this:
try {
...
} catch (org.jenkinsci.plugins.workflow.steps.FlowInterruptedException err) {
if( is_interrupted_by_timeout(err) ) {
echo('It is timeout!')
}
}
P.S. I agree, this is bad Jenkins design.