Jenkins Certification Guide

Certifications Available

Cert	Full Name	Questions	Time	Passing

|------|-----------|-----------|------|---------|

CJE	CloudBees Certified Jenkins Engineer	60	90 min	70%
CJPE	CloudBees Certified Jenkins Platform Engineer	60	90 min	70%

CJE focuses on Jenkins core. CJPE adds CloudBees-specific features (team management, RBAC, plugins).

CJE Exam Domains

Domain	Topics

|--------|--------|

CI/CD & Jenkins Concepts	CI vs CD, Jenkins purpose, build triggers
Jenkins Administration	Install, config, system management
Building Continuous Delivery Pipelines	Declarative Pipeline, Blue Ocean
CD Patterns	Artifacts, deployment strategies, testing
Jenkins Plugins	Core plugins, manage plugins

Declarative Pipeline (Core of Exam)

groovy

// Jenkinsfile — declarative syntax
pipeline {
    agent { label 'linux' }         // Run on nodes with 'linux' label

    environment {
        APP_VERSION = '1.0.0'
        DOCKER_REGISTRY = 'registry.example.com'
        DEPLOY_CREDS = credentials('deploy-ssh-key')  // Inject credentials
    }

    options {
        timeout(time: 30, unit: 'MINUTES')
        buildDiscarder(logRotator(numToKeepStr: '10'))
        disableConcurrentBuilds()
    }

    triggers {
        pollSCM('H/5 * * * *')      // Poll SCM every 5 min
        cron('0 2 * * *')           // Nightly build at 2am
    }

    parameters {
        string(name: 'BRANCH', defaultValue: 'main', description: 'Branch to build')
        booleanParam(name: 'DEPLOY', defaultValue: false, description: 'Deploy?')
        choice(name: 'ENV', choices: ['dev', 'staging', 'prod'], description: 'Target env')
    }

    stages {
        stage('Checkout') {
            steps {
                git branch: "${params.BRANCH}", url: 'https://github.com/org/repo.git'
            }
        }

        stage('Build & Test') {
            parallel {                          // Run in parallel
                stage('Unit Tests') {
                    steps { sh 'npm test' }
                }
                stage('Lint') {
                    steps { sh 'npm run lint' }
                }
            }
        }

        stage('Build Image') {
            steps {
                sh "docker build -t ${DOCKER_REGISTRY}/myapp:${APP_VERSION} ."
                sh "docker push ${DOCKER_REGISTRY}/myapp:${APP_VERSION}"
            }
        }

        stage('Deploy') {
            when {
                expression { params.DEPLOY == true }
                branch 'main'
            }
            steps {
                sh "./deploy.sh ${params.ENV} ${APP_VERSION}"
            }
        }
    }

    post {
        always {
            junit 'test-results/**/*.xml'      // Archive test results
            cleanWs()                          // Clean workspace
        }
        success {
            slackSend message: "Build ${BUILD_NUMBER} succeeded"
        }
        failure {
            emailext to: 'team@example.com', subject: "Build Failed: ${JOB_NAME}"
        }
    }
}

Key Jenkins Concepts

ARCHITECTURE:
  Controller: orchestrates builds, stores config
  Agent/Node: executes build steps (can be Docker, K8s pod, SSH)
  Executor: thread on agent that runs builds

TRIGGERS:
  SCM polling | Webhooks (preferred) | Cron | Upstream build

PLUGINS (know these for exam):
  Pipeline | Git | Docker Pipeline | Kubernetes | Blue Ocean
  Credentials | SonarQube | Nexus Artifact Uploader | Slack Notification
  JUnit | HTML Publisher | Email Extension

CREDENTIALS:
  Stored in Jenkins credentials store (encrypted)
  Types: username/password, SSH key, secret text, secret file, certificate
  Inject via: credentials() binding or withCredentials() block

SHARED LIBRARIES:
  Reusable Groovy code across pipelines
  @Library('my-shared-lib') import
  vars/ directory: global functions
  src/ directory: Groovy classes

MULTIBRANCH PIPELINE:
  Auto-discovers branches and PRs
  Each branch gets own pipeline (from Jenkinsfile)
  PR pipelines can validate before merge

Study Resources

•Jenkins Docs (jenkins.io/doc) — free official documentation

•CloudBees University (university.cloudbees.com) — free tier available

•"Jenkins: The Definitive Guide" — free PDF available

•Practice: Run Jenkins locally with Docker: docker run -p 8080:8080 jenkins/jenkins:lts

Revision Notes

CJE: 60 MCQ, 90 min, 70% pass, CloudBees proctored

MUST KNOW:
  Declarative Pipeline: agent/environment/options/triggers/parameters/stages/post
  Parallel stages: parallel { stage('A'){} stage('B'){} }
  When conditions: branch, expression, environment
  Post conditions: always/success/failure/unstable/changed

CREDENTIALS: never hardcode! Use credentials() or withCredentials()
SHARED LIBRARIES: @Library annotation, vars/ for global functions
MULTIBRANCH: auto-discovers branches, each gets own Jenkinsfile

COMMON EXAM TOPICS:
  Difference: Freestyle vs Pipeline jobs
  Agent: any / label / docker / kubernetes
  Artifact archiving: archiveArtifacts, stash/unstash
  Test results: junit 'results/*.xml'

Jenkins — Certification