Jenkins Pipeline Jenkinsfile load external groovy class

Question

Could anyone advice on how to load external groovy class into the Jenkinsfile ? In general, I would like to build instance by passing parameters via constructor. Sample code below.

Jenkinsfile

stage('Demo stage') {
   //missing part  
  
}

Tools.groovy

public class Demo {
     String message;
     
     Demo(String message) {
        this.message=message;
     }
     

    public void print(def script) {
        script.sh "echo " + message
    }
}

Answer 1

mytools = load 'Tools.groovy'
public class Demo {

}
return new Demo() ;

In your Tools.groovy you have to have a return statement... Since you are looking to call functions inside a class , you have to return new Demo() at the end ,this would return reference of the object to mytools.

In addition to this you can always use groovy class loader.

Answer 2

if your external groovy file is in the same repository that JenkinsFile resides you can simply use "load" as showen below

mytools = load 'Tools.groovy'

If its in another repo, you need to checkout scm before loading the groovy file as below

checkout changelog: false, poll: false, scm: [$class: 'GitSCM', branches: [[name: '*/master']], doGenerateSubmoduleConfigurations: false, extensions: [[$class: 'RelativeTargetDirectory', relativeTargetDir: 'jenkins-scripts']], submoduleCfg: [], userRemoteConfigs: [[credentialsId: '******', url: 'https://github.com/jenkins_scripts.git']]]

Answer 3

It requires a helper function to do so.

Tools.groovy

public class Demo {
    String message;
     
    Demo(String message) {
        this.message = message;
    }

    public void print(def script) {
        script.sh "echo " + message
    }
}

Demo createDemo(String message) {
    new Demo(message)
}

return this

Jenkinsfile

stage('Demo stage') {
   steps {
       script {
           Object lib = load 'path/to/Tools.groovy'
           Object demo = lib.createDemo('a demo')
           demo.print(this)
       }
   }
}