Jenkinsfile update using version control

Question

I've a Jenkinsfile in the master branch of the repository with following code

pipeline {
    agent any
    stages {
        stage('A') {
            steps {
                sh 'echo "Step A"'
            }
        }
    }
}

Now I want to add a new stage B for which I created a git branch update/jenkinsfile and in that branch the Jenkinsfile is now

pipeline {
    agent any
    stages {
        stage('A') {
            steps {
                sh 'echo "Step A"'
            }
        }
        stage('B') {
            steps {
                sh 'echo "Step B"'
            }
        }
    }
}

How do I make Jenkins to use Jenkinsfile from branch B not from master in order to testing the change?

Answer 1

It sounds like you want a when statement.

As I understand it, you want to execute stage B when you are on branch update/jenkinsfile. In order to do this, you need to add a condition to stage B:

pipeline {
    agent any
    stages {
        stage('A') {
            steps {
                sh 'echo "Step A"'
            }
        }
        stage('B') {
            when {
              branch 'update/jenkinsfile'
            }
            steps {
                sh 'echo "Step B"'
            }
        }
    }
}

Note that you also need your jenkins to discover this new branch - this will depend on how you have configured the job. The above assumes that you have a multibranch pipeline job which is configured to include that branch.