Introduction:

In today’s fast-paced software development world, DevOps plays a critical role in automating the build, test, and deployment process. In this blog, I’ll walk you through a complete end-to-end CI/CD pipeline I built using Jenkins on AWS EC2, integrating popular DevOps tools like Git, Maven, SonarQube, Nexus, and Tomcat. This hands-on project not only helped me understand how each tool fits into the software development lifecycle but also gave me real-world experience in deploying a robust and scalable automation pipeline. Whether you're a DevOps beginner or someone brushing up on core concepts, this post will give you a practical view of setting up your own pipeline from scratch.

Tech Stack:

• Git: Source code management

• Maven: Build tool

• SonarQube: Code quality check

• Nexus: Artifact storage

• Tomcat: Webserver for deployment

• Jenkins: CI/CD pipeline

• AWS EC2: Hosting all services

  Step-by-Step Process to Deploy the Application:

  STEP-1: LAUNCH 4 INSTANCES WITH SAME PEM FILE

• JENKINS: T2.MICRO

• TOMCAT: T2.MICRO

• SONAR: T2.MEDIUM (25 GB OF EBS VOLUME)

• NEXUS: T2.MEDIUM (25 GB OF EBS VOLUME)

• SETUP SERVICES IN THEIR RESPECTIVE SERVERS

  

  STEP-2: refer the below scripts to install Jenkins, Tomcat ,Sonar and Nexus on respective servers.

  Jenkins Script

      #STEP-1: INSTALLING GIT
      yum install git -y
  
      #STEP-2: GETTING THE REPO (jenkins.io --> download --> redhat)
      sudo wget -O /etc/yum.repos.d/jenkins.repo \
          https://pkg.jenkins.io/redhat-stable/jenkins.repo
      sudo rpm --import https://pkg.jenkins.io/redhat-stable/jenkins.io-2023.key
      sudo yum upgrade
      # Add required dependencies for the jenkins package
      sudo yum install fontconfig java-21-openjdk
      sudo yum install jenkins
      sudo systemctl daemon-reload
  
      #STEP-3: DOWNLOAD JAVA17 AND JENKINS
      yum install java-17-amazon-corretto -y
      yum install jenkins -y
  
      #STEP-4: RESTARTING JENKINS
      systemctl start jenkins.service
      systemctl status jenkins.service
  

  

  

  Tomcat Script:

      #STEP-1: INSTALL JAVA 17
      yum install java-17-amazon-corretto -y
  
      #STEP-2: DOWNLOAD & EXTRACT TOMCAT
      wget https://downloads.apache.org/tomcat/tomcat-9/v9.0.104/bin/apache-tomcat-9.0.104.tar.gz
      tar -zxvf apache-tomcat-9.0.104.tar.gz
  
      #STEP-3: CONFIGURE TOMCAT USERS (GUI & SCRIPT ACCESS)
      sed -i '56  a\<role rolename="manager-gui"/>' conf/tomcat-users.xml
      sed -i '57  a\<role rolename="manager-script"/>' conf/tomcat-users.xml
      sed -i '58  a\<user username="tomcat" password="admin@123" roles="manager-gui, manager-script"/>' conf/tomcat-users.xml
      sed -i '59  a\</tomcat-users>' conf/tomcat-users.xml
      sed -i '56d' conf/tomcat-users.xml
      #STEP-4: REMOVE IP RESTRICTIONS FOR MANAGER ACCESS
      sed -i '21d' webapps/manager/META-INF/context.xml
      sed -i '22d' webapps/manager/META-INF/context.xml
  
      #STEP-5: START TOMCAT SERVER
      sh bin/startup.sh
  

  

  

  Nexus Script:

      #STEP-1: INSTALL JAVA 17
      yum install java-17-amazon-corretto -y
  
      #STEP-2: DOWNLOAD NEXUS AND EXTRACT
      cd /opt
      wget https://download.sonatype.com/nexus/3/nexus-unix-x86-64-3.79.0-09.tar.gz
      tar -zxvf nexus-unix-x86-64-3.79.0-09.tar.gz
  
      #STEP-3: CREATE NEXUS USER & SET PERMISSIONS
      useradd nexus
      vim /opt/nexus-3.79.0-09/bin/nexus
      # (Edit the file and set) run_as_user="nexus"
  
      #STEP-4: SWITCH TO NEXUS USER AND START SERVICE
      su - nexus
      /opt/nexus-3.79.0-09/bin/nexus start
      /opt/nexus-3.79.0-09/bin/nexus status
  
      #STEP-5: VERIFY NEXUS IS RUNNING
      ps -ef | grep nexus
      ss -tuln | grep 8081
  
      #STEP-6: GET DEFAULT ADMIN PASSWORD
      cat /opt/sonatype-work/nexus3/admin.password
  

  

  

  Sonar Setup:

      #STEP-1: INSTALL JAVA OPENJDK 11
      amazon-linux-extras install java-openjdk11 -y
  
      #STEP-2: DOWNLOAD SONARQUBE
      cd /opt/
      wget https://binaries.sonarsource.com/Distribution/sonarqube/sonarqube-8.9.6.50800.zip
  
      #STEP-3: UNZIP AND CONFIGURE PERMISSIONS
      unzip sonarqube-8.9.6.50800.zip
      useradd sonar
      chown sonar:sonar sonarqube-8.9.6.50800 -R
  
      #STEP-4: SWITCH TO SONAR USER AND START SONARQUBE
      su - sonar
      cd /opt/sonarqube-8.9.6.50800/bin/linux-x86-64/
      sh sonar.sh start
      sh sonar.sh status
  

  STEP-3: Login to Jenkins & Install Plugins

  1. Go to http://<your-ip>:8080 and log in to Jenkins.

  2. Go to Manage Jenkins → Plugin Manager → Available

  3. Install these plugins:

     SonarQube Scanner – for code scanning

     Nexus Artifact Uploader – to upload files to Nexus

     SSH Agent – to send files to another server.

STEP-4:Create a Jenkins pipeline job and write a Jenkins file for deploy a web application, usually we have 2 types of pipelines,

scripted ,declarative

Here i am using scripted pipeline for the Jenkins file

STAGE-1 : GET THE CODE FROM GITHUB TO CI-SERVER
node { stage("Code") { git clone(“repo-link” } }
STAGE-2 : BUILD THE SOURCE CODE: GO TO MANAGE JENKINS >> GLOBAL TOOL CONFIGURATION >> MAVEN ADD INSTALLER WITH THE NAME OF maven WITH VERISON (3.9.9)
stage("Build") { def mavenHome = tool name: "maven3", type: "maven" def mavenCMD = "${mavenHome}/bin/mvn" sh "${mavenCMD} clean package" }
CHECK THE WAR FILE IN JENKINS FOR CONFIRMATION AFTER SUCCESSFULL BUILD

STAGE-3 : SCAN THE SOURCE CODE: LOGIN INTO SONAR GO TO MY ACCOUNT >> SECURITY >> ENTER A TOKEN NAME AND GENERATE A TOKEN

NOW INTEGRATE THE SONAR TO JENKINS MANAGE JENKINS >> CONFIGURE SYSTEM >> SONAR SERVER

stage("CQA") { withSonarQubeEnv('mysonar') { def mavenHome = tool name: "maven3", type: "maven" def mavenCMD = "${mavenHome}/bin/mvn" sh "${mavenCMD} sonar:sonar" } }
AFTER SUCCESSFULL BUILD CHECK FOR ANY BUGS IN THE SONARQUBE DASHBOARD>PROJECTS

STAGE-4: Upload WAR File to Nexus Artifactory

Create a new repository in Nexus:
• Name: new-repo
• Format: maven2 (hosted)
• Version Policy: Releases
• Deployment Policy: Allow Redeploy

Install the Nexus Artifact Uploader plugin in Jenkins.

Go to Jenkins → Pipeline Syntax, choose Nexus Artifact Uploader from the dropdown.

Fill in the required fields:
• Nexus URL
• Repository name (new-repo)
• Group ID, Artifact ID, Version(You can find in the pom.xml file)
• Path to WAR file

Click Generate Pipeline Script and add it to your Jenkinsfile

    stage("Nexus") {
        nexusArtifactUploader artifacts: [[
            artifactId: 'myweb', 
            classifier: '', 
            file: 'target/myweb-8.6.9.war', 
            type: 'war'
        ]],
        credentialsId: 'nexus',
        groupId: 'in.javahome',
        nexusUrl: '34.229.123.124:8081',
        nexusVersion: 'nexus3',
        protocol: 'http',
        repository: 'bhavya-repo',
        version: '8.6.9'
    }

AFTER SUCESSFULL BIULD YOU CAN SEE THE WAR FILES UPLOADED IN NEXUS

STAGE-5 : DEPLOY THE APPLICATION INTO TOMCAT WEB SERVER:

(Put your pem file privte key)

    #!/bin/bash

    # Move Tomcat folder to ec2-user home
    mv apache-tomcat-9.0.104 /home/ec2-user/

    # Change ownership to ec2-user
    chown ec2-user:ec2-user /home/ec2-user/apache-tomcat-9.0.104 -R

    # Switch to tomcat directory
    cd /home/ec2-user/apache-tomcat-9.0.104/bin

    # Stop Tomcat if running
    ./shutdown.sh

    # Start Tomcat
    ./startup.sh

    # Navigate to webapps folder
    cd ../webapps
    pwd

    stage("Deployment") {
        sshagent(['8bce0b0e-c5db-4aac-bf07-4831ca13a760']) {
            sh 'scp -o StrictHostKeyChecking=no target/*.war ec2-user@52.23.240.218:/home/ec2-user/apache-tomcat-9.0.104/webapps/'
        }
    }

AFTER SUCCESSFULL BUILD YOU CAN SEE YOUR WAR FILED DEPLOYED INTO TOMCAT SERVER

CLICK ON YOUR WAR FILE TO VIEW YOUR APPLICATION

Final Pipeline Flow Summary

From Code to Deployment:

1. Developer pushes code to Git

2. Jenkins job triggers → SonarQube analysis

3. Maven builds code → Nexus stores WAR file

4. Jenkins deploys to Tomcat → Application is live

---

✅ What I Learned

• How each DevOps tool works in real-world projects.

• Jenkins integration with multiple tools for continuous integration and delivery.

• Managing AWS instances and implementing security best practices.

• Debugging and automating deployment steps to enhance workflow efficiency.

CONNECT WITH ME ON LINKEDIN TO LEARN AND GROW TOGETHER