Jenkins Pipeline to deploy Java application | Git, Maven, Nexus & Tomcat

Hey techies, in Prev blog we learned how to deploy applications using Jenkins free style job. In this blog i am going to write a pipeline to deploy the java-based application.
But i request you to complete my previous blogs to understand this concept better.

https://devops-cicd.hashnode.dev/deploy-a-java-application-using-jenkins
https://devops-cicd.hashnode.dev/jenkins-integrated-with-nexus

my pipeline contains 4 stages [code, build & Unit Test, Artifact, deploy]

Tools we used for each stage:

• code: GIT

• Build: Maven

• Unit Test: Maven

• Artifact: Nexus

• Deploy: Tomcat

STEP BY STEP PROCESS TO DEPLOY THE APPLICATION:

STEP-1: Launch 3 Instances

• Jenkins

• Nexus

• Tomcat

STEP-2: refer the below scripts to install Jenkins, Tomcat 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

#STEP-3: DOWNLOAD JAVA17 AND JENKINS
yum install java-17-amazon-corretto -y
yum install jenkins -y

#STEP-4: RESTARTING JENKINS (when we download service it will on stopped state)
systemctl start jenkins.service
systemctl status jenkins.service

Tomcat Script:

yum install java-17-amazon-corretto -y
wget https://dlcdn.apache.org/tomcat/tomcat-9/v9.0.98/bin/apache-tomcat-9.0.98.tar.gz
tar -zxvf apache-tomcat-9.0.98.tar.gz
sed -i '56  a\<role rolename="manager-gui"/>' apache-tomcat-9.0.98/conf/tomcat-users.xml
sed -i '57  a\<role rolename="manager-script"/>' apache-tomcat-9.0.98/conf/tomcat-users.xml
sed -i '58  a\<user username="tomcat" password="admin@123" roles="manager-gui, manager-script"/>' apache-tomcat-9.0.98/conf/tomcat-users.xml
sed -i '59  a\</tomcat-users>' apache-tomcat-9.0.98/conf/tomcat-users.xml
sed -i '56d' apache-tomcat-9.0.98/conf/tomcat-users.xml
sed -i '21d' apache-tomcat-9.0.98/webapps/manager/META-INF/context.xml
sed -i '22d'  apache-tomcat-9.0.98/webapps/manager/META-INF/context.xml
sh apache-tomcat-9.0.98/bin/startup.sh

Nexus Script:

yum install java-17-amazon-corretto -y
mkdir /app
cd /app
wget -O nexus.tar.gz https://download.sonatype.com/nexus/3/latest-unix.tar.gz
tar -zxvf nexus.tar.gz
mv nexus-* nexus
useradd nexus
chown -R nexus:nexus *
vim /app/nexus/bin/nexus.rc
sed -i '1s/.*/run_as_user="nexus"/' /app/nexus/bin/nexus.rc
./nexus/bin/nexus start
./nexus/bin/nexus status

STEP-3: Install the following plugins on Jenkins dashborad

• Nexus Artifact Uploader

• Deploy to Container

STEP-4: Create a Pipeline job and write the below Jenkinsfile

pipeline {
    agent any
    tools {
        maven "mymaven"
    }

    stages {
        stage('Code') {
            steps {
                git 'https://github.com/devops0014/one.git'
            }
        }
        stage ("Build") {
            steps {
                sh 'mvn clean package'
            }
        }
        stage ("Artifact") {
            steps {
                nexusArtifactUploader artifacts: [[artifactId: 'myweb', classifier: '', file: 'target/myweb-8.6.9.war', type: 'war']], credentialsId: 'nexus', groupId: 'in.javahome', nexusUrl: '54.227.157.176:8081', nexusVersion: 'nexus3', protocol: 'http', repository: 'myrepo', version: '8.6.9'
            }
        }
        stage ("Deploy") {
            steps {
                deploy adapters: [tomcat9(credentialsId: 'tomcat', path: '', url: 'http://54.156.87.218:8080')], contextPath: 'myapp', war: 'target/*.war'
            }
        }
    }
}

NOTE: use pipeline syntax for getting the scrips for each stage.

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