CI/CD Pipeline with Jenkins, Maven, and Nexus on Ubuntu

This project demonstrates how to set up a complete CI/CD pipeline using Jenkins, Maven, and Nexus on an Ubuntu server. The pipeline automates code build, artifact deployment to Nexus, and deployment to an Nginx web server.

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🚀 Prerequisites

• AWS EC2 Instance: Ubuntu Server (T2 Medium, 30 GB storage)
• Basic knowledge of Linux commands, Jenkins, Maven, and Docker

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⚙️ Setup Steps

1. Create Ubuntu Server

• Instance type: t2.medium
• Storage: 30 GB

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2. Install Jenkins

Follow the official Jenkins installation guide: 👉 Jenkins Installation on Linux

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3. Install Maven

sudo apt install maven -y

• Installed version: Maven 3.8.7

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4. Nexus Installation on Docker

sudo apt install docker.io -y
sudo docker pull sonatype/nexus3
sudo docker volume create nexus-data
sudo docker run -d -p 8081:8081 --name nexus -v nexus-data:/nexus-data sonatype/nexus3

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5. Fetch Nexus Admin Password

docker ps
docker exec -it nexus /bin/bash
cat /nexus-data/admin.password

Example output:

da2a59b0-3c0d-4b8e-b309-fc5d3e0e7c0c

set nexus username = admin
set nexus password = admin123

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6. Install Jenkins Plugins

• Pipeline Maven Integration

• Nexus Artifact Uploader

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7. Configure Maven in Jenkins

Navigate to: Manage Jenkins -> Tools -> Configure Maven installation

• Name: M3
• MAVEN_HOME: /usr/share/maven

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8. Add Global Maven Settings

Navigate to: Manage Jenkins -> Managed Files -> Add new config (Global Maven settings.xml)

Add content:

<servers>
    <server>
      <id>maven-releases</id>
      <username>admin</username>
      <password>admin123</password>
    </server>
    <server>
      <id>maven-snapshots</id>
      <username>admin</username>
      <password>admin123</password>
    </server>
</servers>

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9. Configure Settings.xml on Jenkins Server

ls -l /var/lib/jenkins/.m2/
mkdir -p /var/lib/jenkins/.m2
mkdir -p /var/lib/jenkins/.m2/repository
chown -R jenkins:jenkins /var/lib/jenkins/.m2
sudo chmod -R 755 /var/lib/jenkins/.m2
vim /var/lib/jenkins/.m2/settings.xml

Add:

<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0
                              https://maven.apache.org/xsd/settings-1.0.0.xsd">

  <servers>
    <server>
      <id>maven-releases</id>
      <username>admin</username>
      <password>admin123</password>
    </server>
    <server>
      <id>maven-snapshots</id>
      <username>admin</username>
      <password>admin123</password>
    </server>
  </servers>
</settings>

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10. Update POM.xml

Edit POM.xml with server IP (example: 192.168.18.141).

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11. Jenkinsfile (Pipeline Script)

pipeline {
    agent any

    environment {
        APP_NAME = "myapp"
        MAVEN_REPO = "/tmp/maven-repo"
    }

    stages {
        stage('Checkout Code') {
            steps {
                git branch: 'main', url: 'https://github.com/rohitrawat891997/register-app.git'
            }
        }

        stage('Build with Maven') {
            steps {
                sh "mvn -Dmaven.repo.local=${MAVEN_REPO} clean package"
            }
        }

        stage('Upload to Nexus') {
            steps {
                withMaven(maven: 'M3') {
                    sh "mvn -Dmaven.repo.local=${MAVEN_REPO} clean deploy -s /var/lib/jenkins/.m2/settings.xml -DskipTests"
                }
            }
        }

        stage('Download from Nexus') {
            steps {
                sh """
                curl -u admin:admin123 -O \
                http://192.168.18.141:8081/repository/maven-releases/com/github/jitpack/maven-simple/0.2-SNAPSHOT/maven-simple-0.2-SNAPSHOT.jar
                """
            }
        }

        stage("Deploy using Dockerfile") {
            steps {
                sh """
                docker run -itd --name=tomcat -e  ALLOW_EMPTY_PASSWORD=yes -p 8082:8080 bitnami/tomcat
                docker cp webapp/target/*.war tomcat:/opt/bitnami/tomcat/webapps
                docker restart tomcat
                """
            }
        }
    }
}

### Run these commands for permission

usermod -aG docker  $USER
usermod -aG docker jenkins
newgrp
systemctl restart docker

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12. Configure Sudo Permissions for Jenkins

Edit sudoers file:

sudo vim /etc/sudoers

Add:

jenkins ALL=(ALL) NOPASSWD: /bin/systemctl restart nginx, /bin/rm, /bin/cp

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✅ Final Workflow

1. Jenkins pulls code from GitHub

2. Builds with Maven

3. Uploads artifacts to Nexus

4. Downloads artifact from Nexus

5. Deploys artifact to Tomcat

   URL:- http://localhost:8082/webapp

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