Jenkins: Beginner to Expert

      Ankush More

      From Beginner to Expert

      Table of Contents

      1. Introduction to Jenkins
      2. Getting Started (Beginner Level)
      3. Intermediate Jenkins (Intermediate Level)
      4. Advanced Jenkins (Expert Level)
      5. Jenkins in Production
      6. Troubleshooting and Best Practices
      7. Future of Jenkins

      Introduction to Jenkins

      Jenkins is an open-source automation server that enables developers to build, test, and deploy their applications efficiently. As a cornerstone of DevOps practices, Jenkins facilitates Continuous Integration (CI) and Continuous Deployment (CD) pipelines.

      What is Jenkins?

      Jenkins is a self-contained, open-source automation server written in Java. It provides hundreds of plugins to support building, deploying, and automating any project.

      graph LR
    A[Developer] --> B[Code Repository]
    B --> C[Jenkins Server]
    C --> D[Build]
    C --> E[Test]
    C --> F[Deploy]
    D --> G[Staging Environment]
    E --> G
    F --> H[Production Environment]

      Key Features

      • Extensible: Over 1,500 plugins available
      • Distributed: Master-slave architecture
      • Easy Configuration: Web-based GUI
      • Open Source: Free to use and modify
      • Platform Independent: Runs on various operating systems

      Jenkins Architecture

      graph TB
    subgraph "Jenkins Master"
        A[Jenkins Controller]
        B[Job Scheduler]
        C[Web UI]
        D[Plugin Manager]
    end

    subgraph "Jenkins Agents"
        E[Agent 1Windows]
        F[Agent 2Linux]
        G[Agent 3macOS]
    end

    A --> E
    A --> F
    A --> G

    H[SCMGit/SVN] --> A
    A --> I[Build Artifacts]
    A --> J[Test Reports]
    A --> K[Deployment]

      Getting Started (Beginner Level)

      Chapter 1: Installation and Setup

      System Requirements

      • Java 8 or 11
      • Minimum 256MB RAM (1GB+ recommended)
      • 1GB+ disk space

      Installation Methods

      Windows Installation:

      1. Download Jenkins WAR file
      2. Install Java JDK
      3. Run: java -jar jenkins.war

      Docker Installation:

      docker run -p 8080:8080 -p 50000:50000 -v jenkins_home:/var/jenkins_home jenkins/jenkins:lts
      Bash

      Linux (Ubuntu) Installation:

      sudo apt update
sudo apt install openjdk-11-jdk
wget -q -O - https://pkg.jenkins.io/debian/jenkins.io.key | sudo apt-key add -
sudo sh -c 'echo deb http://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list'
sudo apt update
sudo apt install jenkins
      Bash

      Chapter 2: First Steps with Jenkins

      Initial Setup Wizard

      flowchart TD
    A[Start Jenkins] --> B[Unlock Jenkins]
    B --> C[Install Plugins]
    C --> D[Create Admin User]
    D --> E[Instance Configuration]
    E --> F[Jenkins Ready]

      Creating Your First Job

      1. Freestyle Project: Basic job type for simple automation
      2. Pipeline: Advanced job type using code-as-configuration

      Simple Freestyle Job Example:

      // Build Steps
echo "Hello, Jenkins!"
echo "Building project..."
      Bash

      Chapter 3: Understanding Jenkins Jobs

      Job Types

      graph LR
    A[Jenkins Jobs] --> B[Freestyle Project]
    A --> C[Pipeline]
    A --> D[Multi-configuration Project]
    A --> E[Folder]
    A --> F[Multibranch Pipeline]
    A --> G[Organization Folder]

      Build Triggers

      • Manual: Triggered by user
      • SCM Polling: Check for changes periodically
      • Webhook: Triggered by external events
      • Scheduled: Cron-like scheduling
      graph TD
    A[Build Triggers] --> B[Manual Trigger]
    A --> C[SCM PollingH/15 * * * *]
    A --> D[WebhookGitHub/GitLab]
    A --> E[ScheduledCron Expression]

    B --> F[Jenkins Job]
    C --> F
    D --> F
    E --> F

      Chapter 4: Basic Pipeline Creation

      Declarative Pipeline Syntax

      pipeline {
    agent any

    stages {
        stage('Build') {
            steps {
                echo 'Building...'
                // Build commands here
            }
        }

        stage('Test') {
            steps {
                echo 'Testing...'
                // Test commands here
            }
        }

        stage('Deploy') {
            steps {
                echo 'Deploying...'
                // Deploy commands here
            }
        }
    }

    post {
        always {
            echo 'Pipeline completed'
        }
        success {
            echo 'Pipeline succeeded'
        }
        failure {
            echo 'Pipeline failed'
        }
    }
}
      Groovy

      Intermediate Jenkins (Intermediate Level)

      Chapter 5: Advanced Pipeline Concepts

      Scripted vs Declarative Pipelines

      graph LR
    A[Jenkins Pipelines] --> B[Declarative Pipeline]
    A --> C[Scripted Pipeline]

    B --> D[Structured Syntax]
    B --> E[Built-in Directives]
    B --> F[Easier to Read]

    C --> G[Groovy-based]
    C --> H[More Flexible]
    C --> I[Programmatic Control]

      Pipeline Stages and Steps

      pipeline {
    agent any

    environment {
        DOCKER_REGISTRY = 'your-registry.com'
        APP_NAME = 'myapp'
    }

    parameters {
        choice(name: 'ENVIRONMENT', choices: ['dev', 'staging', 'prod'], description: 'Deployment environment')
        booleanParam(name: 'SKIP_TESTS', defaultValue: false, description: 'Skip test execution')
    }

    stages {
        stage('Checkout') {
            steps {
                git branch: 'main', url: 'https://github.com/user/repo.git'
            }
        }

        stage('Build') {
            steps {
                sh 'mvn clean compile'
            }
        }

        stage('Test') {
            when {
                not { params.SKIP_TESTS }
            }
            parallel {
                stage('Unit Tests') {
                    steps {
                        sh 'mvn test'
                    }
                }
                stage('Integration Tests') {
                    steps {
                        sh 'mvn integration-test'
                    }
                }
            }
        }

        stage('Package') {
            steps {
                sh 'mvn package'
                archiveArtifacts artifacts: 'target/*.jar', fingerprint: true
            }
        }

        stage('Deploy') {
            steps {
                script {
                    if (params.ENVIRONMENT == 'prod') {
                        input message: 'Deploy to production?', ok: 'Deploy'
                    }
                }
                sh "kubectl apply -f k8s/${params.ENVIRONMENT}/"
            }
        }
    }

    post {
        always {
            publishTestResults testResultsPattern: 'target/surefire-reports/*.xml'
            publishHTML([
                allowMissing: false,
                alwaysLinkToLastBuild: true,
                keepAll: true,
                reportDir: 'target/site/jacoco',
                reportFiles: 'index.html',
                reportName: 'Code Coverage Report'
            ])
        }
        failure {
            emailext (
                subject: "Build Failed: ${env.JOB_NAME} - ${env.BUILD_NUMBER}",
                body: "Build failed. Check console output at ${env.BUILD_URL}",
                to: "${env.CHANGE_AUTHOR_EMAIL}"
            )
        }
    }
}
      Groovy

      Chapter 6: Jenkins Plugins and Integrations

      Essential Plugins

      graph TB
    A[Jenkins Plugins] --> B[SCM Plugins]
    A --> C[Build Tools]
    A --> D[Testing Plugins]
    A --> E[Deployment Plugins]
    A --> F[Notification Plugins]

    B --> B1[Git Plugin]
    B --> B2[GitHub Plugin]
    B --> B3[Bitbucket Plugin]

    C --> C1[Maven Plugin]
    C --> C2[Gradle Plugin]
    C --> C3[Docker Plugin]

    D --> D1[JUnit Plugin]
    D --> D2[TestNG Plugin]
    D --> D3[Selenium Plugin]

    E --> E1[Deploy to Container]
    E --> E2[SSH Plugin]
    E --> E3[Kubernetes Plugin]

    F --> F1[Email Extension]
    F --> F2[Slack Plugin]
    F --> F3[Teams Plugin]

      Plugin Management

      // Installing plugins programmatically
def plugins = [
    'git',
    'workflow-aggregator',
    'blueocean',
    'docker-workflow',
    'kubernetes'
]

plugins.each { plugin ->
    if (!Jenkins.instance.pluginManager.getPlugin(plugin)) {
        println "Installing ${plugin}"
        // Installation logic
    }
}
      Groovy

      Chapter 7: Distributed Builds and Agents

      Master-Agent Architecture

      graph TB
    subgraph "Jenkins Master"
        A[Jenkins Controller]
        B[Job Scheduler]
        C[Web Interface]
    end

    subgraph "Build Agents"
        D[Linux Agent 1]
        E[Windows Agent 1]
        F[Docker Agent]
        G[Cloud Agent]
    end

    A --> D
    A --> E
    A --> F
    A --> G

    H[Developer] --> C
    C --> A

    I[Git Repository] --> A
    A --> J[Build Results]

      Agent Configuration

      // Pipeline with specific agent
pipeline {
    agent {
        label 'linux && docker'
    }

    stages {
        stage('Build on Linux') {
            agent {
                dockerfile {
                    filename 'Dockerfile.build'
                    args '-v /var/run/docker.sock:/var/run/docker.sock'
                }
            }
            steps {
                sh 'docker build -t myapp .'
            }
        }

        stage('Test on Windows') {
            agent {
                label 'windows'
            }
            steps {
                bat 'dotnet test'
            }
        }
    }
}
      Groovy

      Chapter 8: Security and Access Control

      Security Realms and Authorization

      graph LR
    A[Jenkins Security] --> B[Authentication]
    A --> C[Authorization]

    B --> D[Jenkins Database]
    B --> E[LDAP]
    B --> F[Active Directory]
    B --> G[OAuth]

    C --> H[Matrix-based]
    C --> I[Role-based]
    C --> J[Project-based]

      Security Best Practices

      1. Enable Security: Always enable Jenkins security
      2. Use HTTPS: Encrypt communication
      3. Regular Updates: Keep Jenkins and plugins updated
      4. Principle of Least Privilege: Grant minimum required permissions
      5. Audit Logs: Monitor and log activities
      // Security configuration example
import jenkins.model.*
import hudson.security.*

def instance = Jenkins.getInstance()
def hudsonRealm = new HudsonPrivateSecurityRealm(false)
hudsonRealm.createAccount("admin", "admin123")
instance.setSecurityRealm(hudsonRealm)

def strategy = new FullControlOnceLoggedInAuthorizationStrategy()
instance.setAuthorizationStrategy(strategy)
instance.save()
      Groovy

      Advanced Jenkins (Expert Level)

      Chapter 9: Jenkins as Code (JCasC)

      Configuration as Code

      # jenkins.yaml
jenkins:
  systemMessage: "Jenkins configured automatically by Jenkins Configuration as Code plugin"

  securityRealm:
    local:
      allowsSignup: false
      users:
        - id: "admin"
          password: "${JENKINS_ADMIN_PASSWORD}"

  authorizationStrategy:
    globalMatrix:
      permissions:
        - "Overall/Administer:admin"
        - "Overall/Read:authenticated"

  nodes:
    - permanent:
        name: "linux-agent"
        remoteFS: "/home/jenkins"
        launcher:
          ssh:
            host: "linux-agent.example.com"
            credentialsId: "ssh-key"

jobs:
  - script: >
      multibranchPipelineJob('my-org/my-repo') {
        branchSources {
          github {
            id('github-source')
            repoOwner('my-org')
            repository('my-repo')
          }
        }
      }
      Groovy

      Shared Libraries

      // vars/buildAndDeploy.groovy
def call(Map config) {
    pipeline {
        agent any

        stages {
            stage('Build') {
                steps {
                    script {
                        buildApp(config.buildTool)
                    }
                }
            }

            stage('Test') {
                steps {
                    script {
                        runTests(config.testFramework)
                    }
                }
            }

            stage('Deploy') {
                steps {
                    script {
                        deployApp(config.environment)
                    }
                }
            }
        }
    }
}

def buildApp(buildTool) {
    switch(buildTool) {
        case 'maven':
            sh 'mvn clean package'
            break
        case 'gradle':
            sh './gradlew build'
            break
        case 'npm':
            sh 'npm ci && npm run build'
            break
        default:
            error "Unsupported build tool: ${buildTool}"
    }
}
      Groovy

      Chapter 10: Advanced Pipeline Patterns

      Complex Pipeline Workflows

      graph TD
    A[Start] --> B[Checkout]
    B --> C[Build]
    C --> D[Unit Tests]
    D --> E[Integration Tests]
    E --> F[Security Scan]
    F --> G[Package]
    G --> H[Deploy to Staging]
    H --> I[Smoke Tests]
    I --> J{Manual Approval}
    J -->|Approved| K[Deploy to Production]
    J -->|Rejected| L[End]
    K --> M[Health Check]
    M --> N{Health OK?}
    N -->|Yes| O[Success]
    N -->|No| P[Rollback]
    P --> Q[Alert Team]
    Q --> L
    O --> L

      Blue-Green Deployment Pipeline

      pipeline {
    agent any

    parameters {
        choice(name: 'DEPLOYMENT_STRATEGY', choices: ['blue-green', 'rolling', 'canary'], description: 'Deployment strategy')
    }

    environment {
        KUBECONFIG = credentials('k8s-config')
        DOCKER_REGISTRY = 'registry.example.com'
        APP_NAME = 'myapp'
        VERSION = "${BUILD_NUMBER}"
    }

    stages {
        stage('Parallel Build and Test') {
            parallel {
                stage('Build Docker Image') {
                    steps {
                        script {
                            docker.build("${DOCKER_REGISTRY}/${APP_NAME}:${VERSION}")
                        }
                    }
                }

                stage('Run Tests') {
                    steps {
                        sh 'npm test'
                        sh 'npm run test:integration'
                    }
                }

                stage('Security Scan') {
                    steps {
                        sh 'npm audit'
                        sh 'docker run --rm -v $(pwd):/app clair-scanner'
                    }
                }
            }
        }

        stage('Deploy to Staging') {
            steps {
                script {
                    deployToEnvironment('staging', VERSION)
                }
            }
        }

        stage('Staging Tests') {
            steps {
                script {
                    runSmokeTests('staging')
                }
            }
        }

        stage('Production Deployment') {
            when {
                branch 'main'
            }
            steps {
                script {
                    switch(params.DEPLOYMENT_STRATEGY) {
                        case 'blue-green':
                            blueGreenDeployment()
                            break
                        case 'rolling':
                            rollingDeployment()
                            break
                        case 'canary':
                            canaryDeployment()
                            break
                    }
                }
            }
        }
    }

    post {
        always {
            publishTestResults testResultsPattern: 'test-results.xml'
            publishHTML([
                allowMissing: false,
                alwaysLinkToLastBuild: true,
                keepAll: true,
                reportDir: 'coverage',
                reportFiles: 'index.html',
                reportName: 'Coverage Report'
            ])
        }
        success {
            slackSend(
                channel: '#deployments',
                color: 'good',
                message: "✅ ${env.JOB_NAME} ${env.BUILD_NUMBER} deployed successfully"
            )
        }
        failure {
            script {
                if (env.BRANCH_NAME == 'main') {
                    // Trigger rollback pipeline
                    build job: 'rollback-pipeline', parameters: [
                        string(name: 'APP_NAME', value: env.APP_NAME),
                        string(name: 'ENVIRONMENT', value: 'production')
                    ]
                }
            }
        }
    }
}

def blueGreenDeployment() {
    // Blue-Green deployment logic
    def currentColor = getCurrentColor()
    def newColor = (currentColor == 'blue') ? 'green' : 'blue'

    echo "Current color: ${currentColor}, deploying to: ${newColor}"

    // Deploy to new color
    sh "kubectl set image deployment/${APP_NAME}-${newColor} ${APP_NAME}=${DOCKER_REGISTRY}/${APP_NAME}:${VERSION}"
    sh "kubectl rollout status deployment/${APP_NAME}-${newColor}"

    // Health check
    def healthCheck = sh(script: "kubectl exec deployment/${APP_NAME}-${newColor} -- curl -f http://localhost:8080/health", returnStatus: true)

    if (healthCheck == 0) {
        // Switch traffic
        sh "kubectl patch service ${APP_NAME} -p '{\"spec\":{\"selector\":{\"color\":\"${newColor}\"}}}'"
        echo "Traffic switched to ${newColor}"

        // Optional: Keep old version for quick rollback
        sleep 60

        // Scale down old version
        sh "kubectl scale deployment ${APP_NAME}-${currentColor} --replicas=0"
    } else {
        error "Health check failed for ${newColor} deployment"
    }
}
      Groovy

      Chapter 11: Monitoring and Observability

      Jenkins Monitoring Stack

      graph TB
    subgraph "Jenkins Monitoring"
        A[Jenkins Metrics]
        B[Application Logs]
        C[Build Metrics]
        D[Performance Data]
    end

    subgraph "Monitoring Tools"
        E[Prometheus]
        F[Grafana]
        G[ELK Stack]
        H[Jaeger]
    end

    A --> E
    B --> G
    C --> E
    D --> H

    E --> F
    G --> F

    F --> I[Alerts]
    I --> J[PagerDuty]
    I --> K[Slack]
    I --> L[Email]

      Monitoring Pipeline

      pipeline {
    agent any

    tools {
        nodejs 'nodejs-16'
    }

    stages {
        stage('Build with Monitoring') {
            steps {
                script {
                    // Start monitoring
                    def startTime = System.currentTimeMillis()

                    try {
                        sh 'npm ci'
                        sh 'npm run build'

                        // Collect metrics
                        def buildTime = System.currentTimeMillis() - startTime
                        publishMetrics([
                            name: 'build_duration_ms',
                            value: buildTime,
                            tags: [
                                job: env.JOB_NAME,
                                branch: env.BRANCH_NAME
                            ]
                        ])

                    } catch (Exception e) {
                        publishMetrics([
                            name: 'build_failure_count',
                            value: 1,
                            tags: [job: env.JOB_NAME]
                        ])
                        throw e
                    }
                }
            }
        }

        stage('Performance Tests') {
            steps {
                script {
                    // Run performance tests
                    sh 'npm run test:performance'

                    // Collect performance metrics
                    def performanceData = readJSON file: 'performance-results.json'
                    publishPerformanceMetrics(performanceData)
                }
            }
        }
    }

    post {
        always {
            // Publish custom metrics
            script {
                publishMetrics([
                    name: 'pipeline_duration_ms',
                    value: currentBuild.duration,
                    tags: [
                        job: env.JOB_NAME,
                        result: currentBuild.result
                    ]
                ])
            }
        }
    }
}

def publishMetrics(Map metrics) {
    // Send metrics to monitoring system
    httpRequest(
        httpMode: 'POST',
        url: 'http://prometheus-gateway:9091/metrics/job/jenkins',
        requestBody: formatPrometheusMetrics(metrics)
    )
}
      Groovy

      Chapter 12: Jenkins at Scale

      Multi-Master Setup

      graph TB
    subgraph "Load Balancer"
        A[HAProxy/Nginx]
    end

    subgraph "Jenkins Masters"
        B[Master 1]
        C[Master 2]
        D[Master 3]
    end

    subgraph "Shared Storage"
        E[NFS/EFS]
        F[Database]
    end

    subgraph "Agent Pool"
        G[Agent 1]
        H[Agent 2]
        I[Agent 3]
        J[Cloud Agents]
    end

    A --> B
    A --> C
    A --> D

    B --> E
    C --> E
    D --> E

    B --> F
    C --> F
    D --> F

    B --> G
    C --> H
    D --> I
    B --> J
    C --> J
    D --> J

      Scaling Strategies

      // Dynamic agent provisioning
pipeline {
    agent none

    stages {
        stage('Provision Agents') {
            steps {
                script {
                    // Calculate required agents based on workload
                    def requiredAgents = calculateRequiredAgents()

                    // Provision cloud agents
                    provisionCloudAgents(requiredAgents)
                }
            }
        }

        stage('Parallel Execution') {
            parallel {
                stage('Build Module 1') {
                    agent {
                        kubernetes {
                            yaml """
                                apiVersion: v1
                                kind: Pod
                                spec:
                                  containers:
                                  - name: maven
                                    image: maven:3.8-jdk-11
                                    command:
                                    - cat
                                    tty: true
                            """
                        }
                    }
                    steps {
                        container('maven') {
                            sh 'mvn clean package'
                        }
                    }
                }

                stage('Build Module 2') {
                    agent {
                        docker {
                            image 'node:16'
                        }
                    }
                    steps {
                        sh 'npm ci && npm run build'
                    }
                }
            }
        }
    }
}

def calculateRequiredAgents() {
    // Logic to calculate required agents based on:
    // - Queue length
    // - Historical data
    // - Resource requirements
    def queueLength = Jenkins.instance.queue.items.length
    def runningBuilds = Jenkins.instance.computers.sum { it.executors.sum { it.isBusy() ? 1 : 0 } }

    return Math.max(queueLength - runningBuilds, 0)
}
      Groovy

      Jenkins in Production

      Chapter 13: Production Deployment Strategies

      Infrastructure as Code

      # docker-compose.yml for Jenkins
version: '3.8'
services:
  jenkins:
    image: jenkins/jenkins:lts
    container_name: jenkins
    restart: unless-stopped
    ports:
      - "8080:8080"
      - "50000:50000"
    volumes:
      - jenkins_home:/var/jenkins_home
      - /var/run/docker.sock:/var/run/docker.sock
    environment:
      - JENKINS_OPTS=--httpPort=8080
      - JAVA_OPTS=-Xmx2g -Xms1g
    depends_on:
      - jenkins-db

  jenkins-db:
    image: postgres:13
    container_name: jenkins-db
    restart: unless-stopped
    environment:
      - POSTGRES_DB=jenkins
      - POSTGRES_USER=jenkins
      - POSTGRES_PASSWORD=jenkins123
    volumes:
      - jenkins_db:/var/lib/postgresql/data

volumes:
  jenkins_home:
  jenkins_db:
      YAML

      Kubernetes Deployment

      # jenkins-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: jenkins
  namespace: jenkins
spec:
  replicas: 1
  selector:
    matchLabels:
      app: jenkins
  template:
    metadata:
      labels:
        app: jenkins
    spec:
      containers:
      - name: jenkins
        image: jenkins/jenkins:lts
        ports:
        - containerPort: 8080
        - containerPort: 50000
        env:
        - name: JAVA_OPTS
          value: "-Xmx2g -Xms1g"
        volumeMounts:
        - name: jenkins-home
          mountPath: /var/jenkins_home
        resources:
          requests:
            memory: "1Gi"
            cpu: "500m"
          limits:
            memory: "4Gi"
            cpu: "2000m"
        livenessProbe:
          httpGet:
            path: /login
            port: 8080
          initialDelaySeconds: 60
          periodSeconds: 10
        readinessProbe:
          httpGet:
            path: /login
            port: 8080
          initialDelaySeconds: 30
          periodSeconds: 5
      volumes:
      - name: jenkins-home
        persistentVolumeClaim:
          claimName: jenkins-pvc
---
apiVersion: v1
kind: Service
metadata:
  name: jenkins
  namespace: jenkins
spec:
  selector:
    app: jenkins
  ports:
  - name: http
    port: 80
    targetPort: 8080
  - name: jnlp
    port: 50000
    targetPort: 50000
  type: LoadBalancer
      YAML

      Chapter 14: Backup and Disaster Recovery

      Backup Strategy

      graph TD
    A[Jenkins Backup Strategy] --> B[Configuration Backup]
    A --> C[Job Backup]
    A --> D[Plugin Backup]
    A --> E[Build History]
    A --> F[Artifacts Backup]

    B --> G[jenkins.yaml]
    B --> H[Security Config]
    B --> I[System Config]

    C --> J[Job Definitions]
    C --> K[Pipeline Scripts]

    D --> L[Installed Plugins]
    D --> M[Plugin Config]

    E --> N[Build Logs]
    E --> O[Test Results]

    F --> P[Binary Artifacts]
    F --> Q[Docker Images]

      Backup Script

      #!/bin/bash
# jenkins-backup.sh

JENKINS_HOME="/var/lib/jenkins"
BACKUP_DIR="/backup/jenkins"
DATE=$(date +%Y%m%d_%H%M%S)
BACKUP_FILE="jenkins_backup_${DATE}.tar.gz"

# Create backup directory
mkdir -p $BACKUP_DIR

# Stop Jenkins service
systemctl stop jenkins

# Create backup
tar -czf $BACKUP_DIR/$BACKUP_FILE \
    --exclude='workspace' \
    --exclude='builds/*/archive' \
    --exclude='logs' \
    --exclude='cache' \
    $JENKINS_HOME

# Restart Jenkins service
systemctl start jenkins

# Upload to cloud storage
aws s3 cp $BACKUP_DIR/$BACKUP_FILE s3://jenkins-backups/

# Clean old backups (keep last 30 days)
find $BACKUP_DIR -name "jenkins_backup_*.tar.gz" -mtime +30 -delete

echo "Backup completed: $BACKUP_FILE"
      Bash

      Disaster Recovery Pipeline

      pipeline {
    agent any

    parameters {
        choice(name: 'RECOVERY_TYPE', choices: ['config-only', 'full-restore'], description: 'Recovery type')
        string(name: 'BACKUP_FILE', description: 'Backup file to restore')
    }

    stages {
        stage('Validate Backup') {
            steps {
                script {
                    // Validate backup file exists and is valid
                    def backupExists = sh(script: "aws s3 ls s3://jenkins-backups/${params.BACKUP_FILE}", returnStatus: true)
                    if (backupExists != 0) {
                        error "Backup file not found: ${params.BACKUP_FILE}"
                    }
                }
            }
        }

        stage('Prepare Recovery') {
            steps {
                script {
                    // Stop Jenkins service
                    sh "sudo systemctl stop jenkins"

                    // Backup current state
                    sh "sudo tar -czf /tmp/jenkins_pre_recovery.tar.gz /var/lib/jenkins"
                }
            }
        }

        stage('Restore') {
            steps {
                script {
                    // Download backup
                    sh "aws s3 cp s3://jenkins-backups/${params.BACKUP_FILE} /tmp/"

                    if (params.RECOVERY_TYPE == 'full-restore') {
                        // Full restore
                        sh "sudo rm -rf /var/lib/jenkins/*"
                        sh "sudo tar -xzf /tmp/${params.BACKUP_FILE} -C /"
                    } else {
                        // Config-only restore
                        sh "sudo tar -xzf /tmp/${params.BACKUP_FILE} -C /tmp/restore"
                        sh "sudo cp -r /tmp/restore/var/lib/jenkins/config.xml /var/lib/jenkins/"
                        sh "sudo cp -r /tmp/restore/var/lib/jenkins/jobs /var/lib/jenkins/"
                    }

                    // Fix permissions
                    sh "sudo chown -R jenkins:jenkins /var/lib/jenkins"
                }
            }
        }

        stage('Verify Recovery') {
            steps {
                script {
                    // Start Jenkins
                    sh "sudo systemctl start jenkins"

                    // Wait for Jenkins to be ready
                    timeout(time: 5, unit: 'MINUTES') {
                        waitUntil {
                            script {
                                def status = sh(script: "curl -s -o /dev/null -w '%{http_code}' http://localhost:8080/login", returnStdout: true)
                                return status == '200'
                            }
                        }
                    }

                    // Verify jobs are accessible
                    sh "curl -f http://localhost:8080/api/json"
                }
            }
        }
    }

    post {
        success {
            slackSend(
                channel: '#ops',
                color: 'good',
                message: "✅ Jenkins disaster recovery completed successfully"
            )
        }
        failure {
            script {
                // Restore from pre-recovery backup
                sh "sudo systemctl stop jenkins"
                sh "sudo rm -rf /var/lib/jenkins/*"
                sh "sudo tar -xzf /tmp/jenkins_pre_recovery.tar.gz -C /"
                sh "sudo chown -R jenkins:jenkins /var/lib/jenkins"
                sh "sudo systemctl start jenkins"
            }

            slackSend(
                channel: '#ops',
                color: 'danger',
                message: "❌ Jenkins disaster recovery failed. Restored to previous state."
            )
        }
    }
}
      Groovy

      Chapter 15: Performance Optimization

      Performance Tuning

      graph TB
    A[Jenkins Performance] --> B[JVM Tuning]
    A --> C[Plugin Optimization]
    A --> D[Build Optimization]
    A --> E[Agent Management]

    B --> B1[Heap Size]
    B --> B2[Garbage Collection]
    B --> B3[JVM Args]

    C --> C1[Remove Unused Plugins]
    C --> C2[Update Plugins]
    C --> C3[Plugin Profiling]

    D --> D1[Parallel Builds]
    D --> D2[Build Caching]
    D --> D3[Workspace Cleanup]

    E --> E1[Agent Provisioning]
    E --> E2[Resource Allocation]
    E --> E3[Load Balancing]

      JVM Optimization

      # Jenkins JVM options
JAVA_OPTS="-Xmx4g -Xms2g \
-XX:+UseG1GC \
-XX:G1HeapRegionSize=16m \
-XX:G1ReservePercent=25 \
-XX:G1NewSizePercent=30 \
-XX:G1MaxNewSizePercent=40 \
-XX:+UnlockExperimentalVMOptions \
-XX:+DisableExplicitGC \
-XX:+AlwaysPreTouch \
-XX:MaxGCPauseMillis=200 \
-XX:+UseLargePages \
-XX:+UseCompressedOops \
-Djava.awt.headless=true \
-Djenkins.install.runSetupWizard=false"
      Groovy

      Build Optimization Pipeline

      pipeline {
    agent any

    options {
        // Optimize build options
        buildDiscarder(logRotator(numToKeepStr: '10'))
        timeout(time: 30, unit: 'MINUTES')
        skipStagesAfterUnstable()
        parallelsAlwaysFailFast()
    }

    stages {
        stage('Optimized Build') {
            parallel {
                stage('Build with Cache') {
                    steps {
                        script {
                            // Use build cache
                            def cacheKey = "${env.JOB_NAME}-${env.BRANCH_NAME}-${hashFiles('package.json')}"

                            if (cacheExists(cacheKey)) {
                                echo "Using cached build"
                                restoreCache(cacheKey)
                            } else {
                                echo "Building and caching"
                                sh 'npm ci'
                                sh 'npm run build'
                                saveCache(cacheKey, 'node_modules')
                            }
                        }
                    }
                }

                stage('Parallel Tests') {
                    steps {
                        script {
                            // Run tests in parallel
                            def testSuites = ['unit', 'integration', 'e2e']
                            def parallelTests = [:]

                            testSuites.each { suite ->
                                parallelTests[suite] = {
                                    sh "npm run test:${suite}"
                                }
                            }

                            parallel parallelTests
                        }
                    }
                }
            }
        }
    }

    post {
        always {
            // Clean workspace to save disk space
            cleanWs()
        }
    }
}

def cacheExists(String key) {
    return sh(script: "test -d /cache/${key}", returnStatus: true) == 0
}

def restoreCache(String key) {
    sh "cp -r /cache/${key}/* ."
}

def saveCache(String key, String path) {
    sh "mkdir -p /cache/${key}"
    sh "cp -r ${path} /cache/${key}/"
}

def hashFiles(String pattern) {
    return sh(script: "find . -name '${pattern}' -exec md5sum {} + | sort | md5sum | cut -d' ' -f1", returnStdout: true).trim()
}
      Groovy

      Troubleshooting and Best Practices

      Chapter 16: Common Issues and Solutions

      Troubleshooting Guide

      graph TD
    A[Jenkins Issues] --> B[Build Failures]
    A --> C[Performance Issues]
    A --> D[Plugin Issues]
    A --> E[Security Issues]

    B --> B1[Check Logs]
    B --> B2[Verify Dependencies]
    B --> B3[Check Agent Status]

    C --> C1[Monitor Resources]
    C --> C2[Optimize Builds]
    C --> C3[Scale Agents]

    D --> D1[Update Plugins]
    D --> D2[Check Compatibility]
    D --> D3[Remove Conflicts]

    E --> E1[Review Permissions]
    E --> E2[Check Credentials]
    E --> E3[Audit Logs]

      Diagnostic Pipeline

      pipeline {
    agent any

    stages {
        stage('System Diagnostics') {
            steps {
                script {
                    // Check system health
                    sh 'df -h'
                    sh 'free -h'
                    sh 'uptime'

                    // Check Jenkins health
                    def jenkinsHealth = Jenkins.instance.getComputer('').getChannel().call(new SystemHealthCheck())
                    echo "Jenkins Health: ${jenkinsHealth}"

                    // Check agent status
                    Jenkins.instance.nodes.each { node ->
                        def computer = node.toComputer()
                        echo "Agent ${node.name}: ${computer.isOnline() ? 'Online' : 'Offline'}"
                    }

                    // Check plugin status
                    def failedPlugins = Jenkins.instance.pluginManager.plugins.findAll { !it.isActive() }
                    if (failedPlugins) {
                        echo "Failed plugins: ${failedPlugins.collect { it.shortName }}"
                    }
                }
            }
        }

        stage('Performance Metrics') {
            steps {
                script {
                    // Collect performance metrics
                    def metrics = [
                        'queue_length': Jenkins.instance.queue.items.length,
                        'running_builds': Jenkins.instance.computers.sum { it.executors.sum { it.isBusy() ? 1 : 0 } },
                        'total_executors': Jenkins.instance.computers.sum { it.numExecutors },
                        'memory_usage': getMemoryUsage()
                    ]

                    echo "Performance Metrics: ${metrics}"

                    // Send metrics to monitoring system
                    sendMetrics(metrics)
                }
            }
        }
    }
}

@NonCPS
def getMemoryUsage() {
    def runtime = Runtime.getRuntime()
    def totalMemory = runtime.totalMemory()
    def freeMemory = runtime.freeMemory()
    def usedMemory = totalMemory - freeMemory

    return [
        'used': usedMemory,
        'total': totalMemory,
        'percentage': (usedMemory / totalMemory) * 100
    ]
}
      Groovy

      Chapter 17: Best Practices

      Pipeline Best Practices

      1. Use Declarative Pipelines: More readable and maintainable
      2. Fail Fast: Stop early on critical failures
      3. Use Shared Libraries: Promote code reuse
      4. Implement Proper Error Handling: Graceful failure handling
      5. Resource Management: Clean up resources properly
      // Best practices example
pipeline {
    agent none

    options {
        timeout(time: 1, unit: 'HOURS')
        buildDiscarder(logRotator(numToKeepStr: '10'))
        skipStagesAfterUnstable()
    }

    environment {
        // Use credentials properly
        DOCKER_REGISTRY = credentials('docker-registry')
        API_KEY = credentials('api-key')
    }

    stages {
        stage('Validate') {
            agent {
                dockerfile {
                    filename 'Dockerfile.ci'
                    reuseNode true
                }
            }
            steps {
                script {
                    // Validate early
                    validatePipeline()
                }
            }
        }

        stage('Build') {
            agent {
                label 'docker'
            }
            steps {
                script {
                    try {
                        // Build with proper error handling
                        buildApplication()
                    } catch (Exception e) {
                        currentBuild.result = 'FAILURE'
                        error("Build failed: ${e.message}")
                    }
                }
            }
            post {
                always {
                    // Clean up build artifacts
                    cleanWs()
                }
            }
        }
    }

    post {
        success {
            // Notify on success
            notifySuccess()
        }
        failure {
            // Notify and handle failure
            notifyFailure()
            archiveArtifacts artifacts: 'logs/**', allowEmptyArchive: true
        }
    }
}

def validatePipeline() {
    // Validate environment
    if (!env.DOCKER_REGISTRY) {
        error "Docker registry not configured"
    }

    // Validate required files
    def requiredFiles = ['Dockerfile', 'package.json', 'tests/']
    requiredFiles.each { file ->
        if (!fileExists(file)) {
            error "Required file not found: ${file}"
        }
    }
}
      Groovy

      Security Best Practices

      // Security-focused pipeline
pipeline {
    agent any

    stages {
        stage('Security Scan') {
            parallel {
                stage('Dependency Scan') {
                    steps {
                        script {
                            // Scan for vulnerable dependencies
                            sh 'npm audit --audit-level high'
                            sh 'docker run --rm -v $(pwd):/app safety check'
                        }
                    }
                }

                stage('SAST Scan') {
                    steps {
                        script {
                            // Static application security testing
                            sh 'sonar-scanner'
                            sh 'bandit -r .'
                        }
                    }
                }

                stage('Container Scan') {
                    steps {
                        script {
                            // Container security scanning
                            sh 'trivy image myapp:latest'
                        }
                    }
                }
            }
        }

        stage('Compliance Check') {
            steps {
                script {
                    // Policy compliance
                    sh 'conftest test --policy policy/ kubernetes/'
                }
            }
        }
    }

    post {
        always {
            // Publish security reports
            publishHTML([
                allowMissing: false,
                alwaysLinkToLastBuild: true,
                keepAll: true,
                reportDir: 'security-reports',
                reportFiles: 'index.html',
                reportName: 'Security Report'
            ])
        }
    }
}
      Groovy

      Future of Jenkins

      Chapter 18: Jenkins Evolution

      Modern Jenkins Architecture

      graph TB
    subgraph "Cloud Native Jenkins"
        A[Jenkins Operator]
        B[Kubernetes Native]
        C[Configuration as Code]
        D[GitOps Integration]
    end

    subgraph "New Features"
        E[Pipeline as Code]
        F[Serverless Builds]
        G[AI/ML Integration]
        H[Enhanced Security]
    end

    subgraph "Ecosystem"
        I[Jenkins X]
        J[Tekton Integration]
        K[Argo Workflows]
        L[GitHub Actions]
    end

    A --> E
    B --> F
    C --> G
    D --> H

    E --> I
    F --> J
    G --> K
    H --> L

      Jenkins X Pipeline

      # jenkins-x.yml
buildPack: none
pipelineConfig:
  pipelines:
    release:
      pipeline:
        agent:
          image: gcr.io/jenkinsxio/builder-go
        stages:
          - name: ci
            steps:
              - name: build
                command: make
                args: ['build']
              - name: test
                command: make
                args: ['test']
              - name: security-scan
                image: aquasec/trivy
                command: trivy
                args: ['fs', '.']
          - name: build-and-push
            steps:
              - name: build-image
                image: gcr.io/kaniko-project/executor:debug
                command: /kaniko/executor
                args:
                  - --dockerfile=Dockerfile
                  - --destination=gcr.io/myproject/myapp:${VERSION}
          - name: deploy
            steps:
              - name: deploy-staging
                image: gcr.io/jenkinsxio/builder-kubectl
                command: kubectl
                args: ['apply', '-f', 'k8s/staging/']
      YAML

      Chapter 19: Integration with Modern DevOps Tools

      GitOps with Jenkins

      // GitOps pipeline
pipeline {
    agent any

    environment {
        GITOPS_REPO = 'https://github.com/myorg/gitops-config.git'
        GITOPS_BRANCH = 'main'
    }

    stages {
        stage('Build and Test') {
            steps {
                sh 'docker build -t myapp:${BUILD_NUMBER} .'
                sh 'docker run --rm myapp:${BUILD_NUMBER} npm test'
            }
        }

        stage('Update GitOps Repository') {
            steps {
                script {
                    // Clone GitOps repository
                    git branch: env.GITOPS_BRANCH, url: env.GITOPS_REPO, credentialsId: 'git-credentials'

                    // Update image tag in Kubernetes manifests
                    sh """
                        sed -i 's|image: myapp:.*|image: myapp:${BUILD_NUMBER}|' k8s/production/deployment.yaml
                        git add k8s/production/deployment.yaml
                        git commit -m "Update myapp to version ${BUILD_NUMBER}"
                        git push origin ${GITOPS_BRANCH}
                    """
                }
            }
        }
    }
}
      Groovy

      Serverless Jenkins

      # serverless-jenkins.yml
apiVersion: tekton.dev/v1beta1
kind: Pipeline
metadata:
  name: serverless-build
spec:
  params:
    - name: git-url
      type: string
    - name: git-revision
      type: string
  workspaces:
    - name: shared-data
  tasks:
    - name: fetch-source
      taskRef:
        name: git-clone
      workspaces:
        - name: output
          workspace: shared-data
      params:
        - name: url
          value: $(params.git-url)
        - name: revision
          value: $(params.git-revision)

    - name: build-and-test
      taskRef:
        name: buildah
      runAfter:
        - fetch-source
      workspaces:
        - name: source
          workspace: shared-data
      params:
        - name: IMAGE
          value: myapp:latest
      YAML

      Chapter 20: Conclusion and Next Steps

      Key Takeaways

      1. Jenkins Evolution: From simple CI tool to comprehensive DevOps platform
      2. Cloud Native: Kubernetes integration and cloud-native architectures
      3. Automation: Infrastructure as Code and GitOps practices
      4. Security: Integrated security scanning and compliance
      5. Scalability: Distributed builds and cloud provisioning

      Learning Path

      graph TD
    A[Start Here] --> B[Basic Jenkins]
    B --> C[Pipeline Basics]
    C --> D[Plugin Ecosystem]
    D --> E[Distributed Builds]
    E --> F[Advanced Pipelines]
    F --> G[Security & Compliance]
    G --> H[Production Deployment]
    H --> I[Monitoring & Observability]
    I --> J[Cloud Native Jenkins]
    J --> K[Jenkins Expert]

      Next Steps for Different Levels

      Beginner:

      • Set up local Jenkins instance
      • Create first pipeline
      • Learn basic plugins
      • Practice with sample projects

      Intermediate:

      • Implement CI/CD for real projects
      • Configure distributed builds
      • Learn shared libraries
      • Implement security practices

      Advanced:

      • Design enterprise Jenkins architecture
      • Implement GitOps workflows
      • Contribute to Jenkins ecosystem
      • Mentor other developers

      Resources for Continued Learning

      Appendices

      Appendix A: Jenkinsfile Templates

      Basic Web Application Pipeline

      pipeline {
    agent any

    tools {
        nodejs '16'
    }

    stages {
        stage('Checkout') {
            steps {
                checkout scm
            }
        }

        stage('Install Dependencies') {
            steps {
                sh 'npm ci'
            }
        }

        stage('Lint') {
            steps {
                sh 'npm run lint'
            }
        }

        stage('Test') {
            steps {
                sh 'npm test'
            }
        }

        stage('Build') {
            steps {
                sh 'npm run build'
            }
        }

        stage('Deploy') {
            when {
                branch 'main'
            }
            steps {
                sh 'npm run deploy'
            }
        }
    }

    post {
        always {
            publishTestResults testResultsPattern: 'test-results.xml'
        }
    }
}
      Groovy

      Appendix B: Useful Scripts

      Jenkins Backup Script

      #!/bin/bash
# Complete Jenkins backup script
set -e

JENKINS_HOME="/var/lib/jenkins"
BACKUP_DIR="/backups/jenkins"
RETENTION_DAYS=30

# Create backup directory
mkdir -p "$BACKUP_DIR"

# Generate backup filename
BACKUP_FILE="jenkins-backup-$(date +%Y%m%d-%H%M%S).tar.gz"

# Create backup
tar -czf "$BACKUP_DIR/$BACKUP_FILE" \
    --exclude='workspace' \
    --exclude='builds/*/archive' \
    --exclude='logs' \
    --exclude='cache' \
    --exclude='war' \
    "$JENKINS_HOME"

# Upload to S3 (optional)
if command -v aws &> /dev/null; then
    aws s3 cp "$BACKUP_DIR/$BACKUP_FILE" "s3://jenkins-backups/"
fi

# Cleanup old backups
find "$BACKUP_DIR" -name "jenkins-backup-*.tar.gz" -mtime +$RETENTION_DAYS -delete

echo "Backup completed: $BACKUP_FILE"
      Groovy

      Appendix C: Troubleshooting Commands

      # Check Jenkins logs
sudo journalctl -u jenkins -f

# Check disk space
df -h

# Check memory usage
free -h

# Check Jenkins process
ps aux | grep jenkins

# Check port usage
netstat -tlnp | grep 8080

# Restart Jenkins
sudo systemctl restart jenkins

# Check Jenkins configuration
sudo -u jenkins java -jar /usr/share/jenkins/jenkins.war --help
      Groovy

      This comprehensive Jenkins guide covers everything from basic setup to advanced enterprise deployments, with practical examples and real-world

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