30Jenkins

30.1 Architecture

• Controller — orchestrator; stores config, schedules jobs, serves UI
• Agent — worker (formerly "slave") that runs builds
• Executor — slot inside an agent (parallel job capacity)
• Job — a defined build (freestyle or pipeline)
• Build — one execution of a job

30.2 Declarative Pipeline (modern default)

// Jenkinsfile
pipeline {
  agent any

  options {
    timeout(time: 30, unit: 'MINUTES')
    timestamps()
    disableConcurrentBuilds()
    buildDiscarder(logRotator(numToKeepStr: '20'))
  }

  environment {
    NODE_ENV = 'test'
    CI = 'true'
  }

  triggers {
    pollSCM('H/5 * * * *')   // poll git every 5 min
    cron('H 2 * * *')        // nightly
  }

  stages {
    stage('Checkout') {
      steps { checkout scm }
    }
    stage('Install') {
      steps { sh 'npm ci' }
    }
    stage('Lint') {
      steps { sh 'npm run lint' }
    }
    stage('Test') {
      parallel {
        stage('Unit') { steps { sh 'npm run test:unit' } }
        stage('E2E')  { steps { sh 'npx playwright test' } }
      }
    }
    stage('Deploy') {
      when { branch 'main' }
      steps { sh './deploy.sh' }
    }
  }

  post {
    always {
      junit 'test-results/junit.xml'
      archiveArtifacts artifacts: 'playwright-report/**', allowEmptyArchive: true
    }
    failure {
      mail to: 'team@acme.com', subject: "FAILED: ${env.JOB_NAME} #${env.BUILD_NUMBER}",
           body: "See ${env.BUILD_URL}"
    }
  }
}

30.3 Scripted Pipeline (older Groovy DSL)

node('linux') {
  stage('checkout') { checkout scm }
  stage('install')  { sh 'npm ci' }
  stage('test') {
    try {
      sh 'npx playwright test'
    } finally {
      junit 'test-results/junit.xml'
    }
  }
}

30.4 Credentials & secrets

// Use a credential id stored in Jenkins
withCredentials([
  string(credentialsId: 'JIRA_TOKEN', variable: 'JIRA_TOKEN'),
  usernamePassword(credentialsId: 'docker-hub', usernameVariable: 'DOCKER_USER', passwordVariable: 'DOCKER_PASS')
]) {
  sh 'docker login -u $DOCKER_USER -p $DOCKER_PASS'
}

30.5 Parallel + matrix

// Static parallel
stage('Test') {
  parallel {
    stage('chromium') { agent { label 'linux' }; steps { sh 'npx playwright test --project=chromium' } }
    stage('firefox')  { agent { label 'linux' }; steps { sh 'npx playwright test --project=firefox' } }
    stage('webkit')   { agent { label 'mac' };   steps { sh 'npx playwright test --project=webkit' } }
  }
}

// Matrix (axis cross-product)
matrix {
  axes {
    axis { name 'OS';      values 'linux','mac','windows' }
    axis { name 'BROWSER'; values 'chromium','firefox' }
  }
  stages {
    stage('test') {
      agent { label "${OS}" }
      steps { sh "npx playwright test --project=${BROWSER}" }
    }
  }
}

30.6 Shared libraries

// vars/runPlaywright.groovy
def call(Map config = [:]) {
  sh "npx playwright test --shard=${config.shard ?: '1/1'}"
  junit 'test-results/junit.xml'
}

// Jenkinsfile in any repo
@Library('test-pipeline-lib') _
pipeline {
  agent any
  stages {
    stage('test') {
      steps { runPlaywright(shard: '1/4') }
    }
  }
}

30.7 Common plugins for SDETs

30.8 Jenkins vs GitHub Actions vs GitLab CI