Jenkins Groovy how to call methods from @NonCPS method without ending pipeline

Question

I need to parse some JSON in a Jenkins Pipeline and call some regular methods in a loop, however the script always exits after the first function call. How to do this?

import groovy.json.JsonSlurper
import com.cloudbees.groovy.cps.NonCPS

@NonCPS
def myMethod(String json) {
    def jsonSlurper = new JsonSlurper()
    def jsonObject = jsonSlurper(json)
    jsonObject.each {
        obj ->
            switch(obj.name) {
                case "foo":
                    doAThing(obj)
                    break
                case "bar":
                    doAnotherThing(obj)
                    break
            }
    }
}

In the above example, even with a json object like:

[{
    "name": "foo"
}, {
    "name": "bar"
}]

...the pipeline always exits after the first iteration. This is presumably due to mixing sync and async functions. Is there any way to do this?

Polarity

Have you noticed the typo: def jsonObject = jsonSurper(json) (missing "l" in the right part)? – Granvillegranvillebarker

It's just a typo in the post, not the actual script... But good eye @Granvillegranvillebarker – Polarity

You might have faced this: issues.jenkins-ci.org/browse/JENKINS-31314 or this: issues.jenkins-ci.org/browse/JENKINS-26481 – Granvillegranvillebarker

Yes, issue 26481 looks likely to be the same. – Polarity

Answer 1

I've resolved this issue essentially by doing the following:

import groovy.json.JsonSlurper

def myMethod(String json) {
    def jsonSlurper = new JsonSlurper()
    def jsonObject = jsonSlurper(json)
    jsonSlurper = null
    for(int i = 0; i < jsonObject.size(); i++) {
        switch(jsonObject[i].name) {
            case "foo":
                doAThing(jsonObject[i])
                break
            case "bar":
                doAnotherThing(jsonObject[i])
                break
        }
    }
}

Immediately destroy the JsonSlurper instance after it's used, remove @NonCPS annotation, switch to a c-style for loop instead of each.

Polarity

maybe you also have an idea on how to solve this #44629538 -- what should we do to this to make it work in Jenkins? – Aglimmer

Answer 2

Just to clarify, this is documented as an unsupported feature - https://github.com/jenkinsci/workflow-cps-plugin/#technical-design

You may not call regular (CPS-transformed) methods, or Pipeline steps, from a @NonCPS method, so they are best used for performing some calculations before passing a summary back to the main script.

Aplomb