Jenkinsfile 'parallel' directive

Declarative Matrix is a great feature for running parallel tasks. It allows you to execute the defined stages (incl. post build actions) for every configuration defined in the matrix directive without code duplication.

Example:

pipeline {
    agent none
    stages {
        stage('Test') {
            matrix {
                agent {
                    label "${PLATFORM}-agent"
                }
                axes {
                    axis {
                        name 'PLATFORM'
                        values 'linux', 'windows'
                    }
                }
                stages {
                    stage('Test') {
                        steps {
                            echo "Do Test for ${PLATFORM}"
                        }
                    }
                }
                post {
                    always {
                        junit "**/TEST-*.xml"
                    }
                }
            }
        }
    }
}

Quote from a Jenkins blog post:

An equivalent pipeline created without matrix would easily be several times larger, and much harder to understand and maintain.

You can use either declarative or script based for doing parallel work. The script based docs for parallel can be found here: https://jenkins.io/doc/book/pipeline/jenkinsfile/#advanced-scripted-pipeline

They give the following example...

stage('Build') {
    /* .. snip .. */
}

stage('Test') {
    parallel linux: {
        node('linux') {
            checkout scm
            try {
                unstash 'app'
                sh 'make check'
            }
            finally {
                junit '**/target/*.xml'
            }
        }
    },
    windows: {
        node('windows') {
            /* .. snip .. */
        }
    }
}

For declarative, I believe you'll do this:

stage('Build') {
    steps {
        parallel (
            "Windows" : {
                echo 'done'
            },
            "Linux" : {
                echo 'done'
            }
        )
     }
}

Since Declarative Pipeline 1.2, the preferred declarative syntax is:

pipeline {
    agent none
    stages {
        stage('Run Tests') {
            parallel {
                stage('Test On Windows') {
                    agent {
                        label "windows"
                    }
                    steps {
                        bat "run-tests.bat"
                    }
                    post {
                        always {
                            junit "**/TEST-*.xml"
                        }
                    }
                }
                stage('Test On Linux') {
                    agent {
                        label "linux"
                    }
                    steps {
                        sh "run-tests.sh"
                    }
                    post {
                        always {
                            junit "**/TEST-*.xml"
                        }
                    }
                }
            }
        }
    }
}