Java Web Calculator – Manual CI/CD (Multi-Version Deployment)

This project demonstrates a manual build–stage–deploy pipeline for a Java-based Web Calculator App, progressively enhanced across three versions:

Version	Features Included	WAR File Name	Description
v0.0.1	Addition only	webapp-add-0.0.1.war	Basic calculator with addition feature
v0.0.2	Addition + Subtraction	webapp-add-sub-0.0.2.war	Enhanced version with subtraction functionality
v0.0.3	Addition + Subtraction + Multiplication	webapp-add-sub-mul-0.0.3.war	Final version with multiplication added

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⚙️ Infrastructure Overview

Server	Purpose	Key Ports	Tools Installed
Build Server	Compiles and packages the code using Maven	22	OpenJDK 17, Maven, Git
Nexus Server (Staging)	Stores the .war artifacts	22, 8081	OpenJDK 17, Nexus Repository 3
Deploy Server	Hosts the final app via Tomcat	22, 8080	OpenJDK 17, Apache Tomcat 9

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🧱 1. Build Server Setup & Packaging

Steps

# 1️⃣ Hostname setup
sudo hostnamectl set-hostname build
sudo init 6

# 2️⃣ System update & Java installation
sudo apt -y update
sudo apt install openjdk-17-jre-headless -y

# 3️⃣ Install Maven
sudo apt install maven -y
java -version
mvn -version

# 4️⃣ Clone the repository
git clone https://github.com/mrtechreddy/Java-Web-Calculator-App.git
cd Java-Web-Calculator-App/

# 5️⃣ Validate & package source
mvn validate
mvn clean package

# 6️⃣ Verify WAR files in target/
cd target/
ls

Multi-Version Packaging Process

Each time a feature is added, the app is rebuilt with a version tag:

Step	Feature Added	Command	Output Artifact
1	Addition	mvn clean package	webapp-add-0.0.1.war
2	Addition + Subtraction	Update code → mvn clean package	webapp-add-sub-0.0.2.war
3	Addition + Sub + Mul	Update code → mvn clean package	webapp-add-sub-mul-0.0.3.war

Deploy to Nexus

Update your pom.xml or /etc/maven/settings.xml:

<distributionManagement>
  <repository>
    <id>Java-Cal-App</id>
    <url>http://51.21.200.175:8081/repository/Java-Cal-App/</url>
  </repository>
</distributionManagement>

Then push build artifacts:

mvn deploy

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🧩 2. Nexus Repository Server (Staging)

Setup Steps

sudo hostnamectl set-hostname nexus
sudo init 6
sudo apt -y update
sudo apt install openjdk-17-jre-headless -y

# Download and extract Nexus
wget https://download.sonatype.com/nexus/3/nexus-3.85.0-03-linux-x86_64.tar.gz
tar -xvzf nexus-3.85.0-03-linux-x86_64.tar.gz
cd nexus-3.85.0-03/bin/

# Start Nexus service
./nexus start
sudo apt install net-tools -y
sudo netstat -ntpl

Access Nexus

• URL: http://51.21.200.175:8081

• Login:

  • Username: admin
  • Password: /home/ubuntu/sonatype-work/nexus3/admin.password

Create a hosted Maven repository named Java-Cal-App.

After each deployment:

Version	Artifact Path
0.0.1	/repository/Java-Cal-App/com/web/cal/webapp-add/0.0.1/webapp-add-0.0.1.war
0.0.2	/repository/Java-Cal-App/com/web/cal/webapp-add-sub/0.0.2/webapp-add-sub-0.0.2.war
0.0.3	/repository/Java-Cal-App/com/web/cal/webapp-add-sub-mul/0.0.3/webapp-add-sub-mul-0.0.3.war

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🧾 3. Deploy Server (Tomcat Deployment)

Setup

sudo hostnamectl set-hostname deploy
sudo init 6
sudo apt -y update
sudo apt install openjdk-17-jre-headless -y

# Download Apache Tomcat 9
wget https://dlcdn.apache.org/tomcat/tomcat-9/v9.0.111/bin/apache-tomcat-9.0.111.tar.gz
tar -xvzf apache-tomcat-9.0.111.tar.gz
cd apache-tomcat-9.0.111/

# Configure admin access
vi conf/tomcat-users.xml
# Add:
# <user username="admin" password="admin123" roles="manager-gui,admin-gui"/>

# Remove access restrictions
sudo vi ./webapps/manager/META-INF/context.xml
sudo vi ./webapps/host-manager/META-INF/context.xml
# Comment out or remove <Valve ...> line

# Start Tomcat
./bin/startup.sh

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Deploy WAR Files (Progressive Versions)

Deploy v0.0.1 (Addition Only)

cd apache-tomcat-9.0.111/webapps/
wget http://<NEXUS-IP>:8081/repository/Java-Cal-App/com/web/cal/webapp-add/0.0.1/webapp-add-0.0.1.war

Access → http://<DEPLOY-IP>:8080/webapp-add

Deploy v0.0.2 (Add + Sub)

wget http://<NEXUS-IP>:8081/repository/Java-Cal-App/com/web/cal/webapp-add-sub/0.0.2/webapp-add-sub-0.0.2.war

Access → http://<DEPLOY-IP>:8080/webapp-add-sub

Deploy v0.0.3 (Add + Sub + Mul)

wget http://<NEXUS-IP>:8081/repository/Java-Cal-App/com/web/cal/webapp-add-sub-mul/0.0.3/webapp-add-sub-mul-0.0.3.war

Access → http://<DEPLOY-IP>:8080/webapp-add-sub-mul

Restart Tomcat after each deployment:

./bin/shutdown.sh
./bin/startup.sh

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🧮 Validation Summary

Stage	Output	Verification
Build	.war in /target	ls target/
Stage	Artifact in Nexus	Nexus GUI → browse Java-Cal-App
Deploy	App running in browser	Access via Tomcat on port 8080

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🧰 Troubleshooting

Issue	Cause	Fix
Nexus not reachable	Service not started	cd nexus-3.85.0-03/bin && ./nexus start
Maven deploy fails	Wrong repo credentials	Check <servers> in settings.xml
Tomcat 403 error	Context.xml restricted	Comment out <Valve> line
WAR not visible	Cached deployment	Clear /webapps and redeploy

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🧠 Tech Stack

• Java 17
• Apache Maven 3
• Sonatype Nexus 3
• Apache Tomcat 9
• Ubuntu 22.04 LTS (AWS EC2)

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👨‍💻 Author

Sivaiah Jagadapi Power BI Developer | DevOps Learner | Cloud Automation Explorer 📍 Hyderabad, India 🗂 Glintsoft Infotech Pvt Ltd 📧 [email protected]

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🏁 End-to-End Flow (All Versions)

Source Code v1 → Build (Maven) → WAR v0.0.1 → Nexus Repo → Tomcat Deploy (Addition)
        ↓
Source Code v2 → Build (Maven) → WAR v0.0.2 → Nexus Repo → Tomcat Deploy (Add + Sub)
        ↓
Source Code v3 → Build (Maven) → WAR v0.0.3 → Nexus Repo → Tomcat Deploy (Add + Sub + Mul)

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✅ Final Outcome: A fully working 3-tier manual CI/CD pipeline demonstrating Java web app build, artifact staging in Nexus, and deployment to Tomcat — versioned incrementally as new calculator features are added.

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