How can I parameterize Jenkinsfile jobs

Question

I have Jenkins Pipeline jobs, where the only difference between the jobs is a parameter, a single "name" value, I could even use the multibranch job name (though not what it's passing as JOB_NAME which is the BRANCH name, sadly none of the envs look suitable without parsing). It would be great if I could set this outiside of the Jenkinsfile, since then I could reuse the same jenkinsfile for all the various jobs.

Answer 1

Basically you need to create a jenkins shared library example name myCoolLib and have a full declarative pipeline in one file under vars, let say you call the file myFancyPipeline.groovy.

Wanted to write my examples but actually I see the docs are quite nice, so I'll copy from there. First the myFancyPipeline.groovy

def call(int buildNumber) {
  if (buildNumber % 2 == 0) {
    pipeline {
      agent any
      stages {
        stage('Even Stage') {
          steps {
            echo "The build number is even"
          }
        }
      }
    }
  } else {
    pipeline {
      agent any
      stages {
        stage('Odd Stage') {
          steps {
            echo "The build number is odd"
          }
        }
      }
    }
  }
}

and then aJenkinsfile that uses it (now has 2 lines)

@Library('myCoolLib') _
evenOrOdd(currentBuild.getNumber())

Obviously parameter here is of type int, but it can be any number of parameters of any type.

I use this approach and have one of the groovy scripts that has 3 parameters (2 Strings and an int) and have 15-20 Jenkinsfiles that use that script via shared library and it's perfect. Motivation is of course one of the most basic rules in any programming (not a quote but goes something like): If you have "same code" at 2 different places, something is not right.

Answer 2

Add this to your Jenkinsfile:

properties([
  parameters([
    string(name: 'myParam', defaultValue: '')
  ])
])

Then, once the build has run once, you will see the "build with parameters" button on the job UI.

There you can input the parameter value you want.

In the pipeline script you can reference it with params.myParam