how to return some values to the caller of the Jenkins plugin

[long song]

Hi,

Is there a way that I can receive a string value from running a Jenkins plugin in the Jenkins pipeline script ?

// the myResult is always null after running the Jenkins plugin "MyPlugin"
pipeline {
   agent any
   stages {
      stage('MyPlugin: MyPlugin Run') {
         steps {
             script {
                def myResult = MyPlugin Parameter1: value1, Parameter2: value2
                println "$myResult"  
             }
         }
      }
   }

Here is the MyPlugin implementation.

public class MyPluginBuilder extends Builder implements SimpleBuildStep {

     @Override

     public void perform(@Nonnull Run<?, ?> run, @Nonnull FilePath workspace, @Nonnull Launcher launcher, @Nonnull TaskListener listener) throws IOException, InterruptedException { ... }

}

The return type of the method perform() is void.

By design, Jenkins doesn't want to return anything back.

To get the running result, I am thinking to store the running result as an artifact and parse it out after running MyPlugin.

Do you have some good practice that I can receive the running result from the Jenkins Plugin ?

Thanks !

Long

[Ullrich Hafner]

It is possible to return values from a step (but not from a SimpleBuildStep) 

Before I go into details we need to make sure that this approach makes senes, your requirements are not clear: 

- What is in the value that you want to return? 

- Why do you want to return a value? 

- What do you want to do with the value?

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[long song]

Here is how I use the plugin the pipeline script

        steps {
             script {
                def myResult = MyPlugin Parameter1: value1, Parameter2: value2
                println "$myResult"  
             }
         }

I expect to return a Json string or a map object which can contain running status such as "repo: xxx, version: xxx, total incidents: xxx ..."

Are you talking about the interface hudson.tasks.BuildStep ? It returns a boolean but can't transport much infor. 

boolean perform(AbstractBuild<?,?> build, Launcher launcher, BuildListener listener) throws InterruptedException, IOException;

To get the running result, I am thinking to store the running result as an artifact and parse it out after running MyPlugin.

Do you have some good practice that I can receive the running result from the Jenkins Plugin ?

Thanks!

To view this discussion on the web visit https://groups.google.com/d/msgid/jenkinsci-dev/DB6814A1-964E-40B2-B048-595D967EA10F%40gmail.com.

[Ullrich Hafner]

Am 21.06.2021 um 00:52 schrieb long song <songl...@gmail.com>:

Here is how I use the plugin the pipeline script

        steps {
             script {
                def myResult = MyPlugin Parameter1: value1, Parameter2: value2
                println "$myResult"  
             }
         }

I expect to return a Json string or a map object which can contain running status such as "repo: xxx, version: xxx, total incidents: xxx ..."

Is your real requirement just to print out a structured text? Then use the Jenkins logger in your BuildStep. Then you don’t need a return value. 

Are you talking about the interface hudson.tasks.BuildStep ?

No, this could be done with a  `org.jenkinsci.plugins.workflow.steps.Step`

It returns a boolean but can't transport much infor. 

boolean perform(AbstractBuild<?,?> build, Launcher launcher, BuildListener listener) throws InterruptedException, IOException;

To get the running result, I am thinking to store the running result as an artifact and parse it out after running MyPlugin.

This still looks too complicated. Use the Tell-Don't-Ask principle (https://martinfowler.com/bliki/TellDontAsk.html)

Tell your Jenkins plugin what it should display and do not get values and work with these values. 

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[Jesse Glick]

Beware that returning a value from a `Step` means that your step cannot be used naturally in Declarative Pipeline (only by “cheating” with a `script` block). If values need to be passed to other parts of a build, it may be better to use a block-scoped step and define environment variables (this can be done either in a first-class `Step` or in a `SimpleBuildWrapper`), though that assumes plain `String`s rather than structured objects:

yourPlugin(param1: 'one', param2: 'two') {

  sh 'echo using $VERSION from $REPO'

}

[long song]

hi Ullrich,

In my actual use case, I don't just print it out, but need to call other APIs with the result value.

Thanks for your suggestion. I will have a try to implement the"org.jenkinsci.plugins.workflow.steps.Step"

best regards,

Long

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[long song]

hi Jesse,

Thank you for the input. 

Defining environment variables should be a good solution for my case.

thanks!

Long

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[Ullrich Hafner]

Am 22.06.2021 um 19:34 schrieb long song <songl...@gmail.com>:

hi Ullrich,

In my actual use case, I don't just print it out, but need to call other APIs with the result value.

Thanks for your suggestion. I will have a try to implement the"org.jenkinsci.plugins.workflow.steps.Step"

Then this is the wrong approach. Either call the API from your plugin or store the results in an object that is controlled by Jenkins (Action).

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