CI/CD Pipeline with Kubernetes

A Spring Boot web application with a fully automated CI/CD pipeline that builds, tests, containerizes, and deploys to an Amazon EKS cluster using Jenkins.

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Overview

This project demonstrates a production-style CI/CD workflow for a Java Maven application. Jenkins orchestrates every phase of the pipeline — from running tests and bumping the Maven version, to publishing a Docker image and applying the updated Kubernetes manifest on EKS.

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Architecture

 Developer Push
      |
      v
 ┌─────────────┐
 │   Jenkins   │  (pipeline defined in Jenkinsfile)
 └──────┬──────┘
        │
        ├─── 1. mvn test
        │
        ├─── 2. Increment Maven version (pom.xml)
        │
        ├─── 3. mvn package  →  java-maven-app-<version>.jar
        │
        ├─── 4. docker build  →  whispernet/java-app-k8s-cicd:<version>
        │         docker push  →  Docker Hub
        │
        ├─── 5. envsubst java-depl.yaml
        │         kubectl apply   →  Amazon EKS
        │
        └─── 6. git commit & push  (updated pom.xml version)

                        Amazon EKS
                   ┌─────────────────────────────┐
                   │  Deployment (2 replicas)     │
                   │  ┌──────────┐ ┌──────────┐  │
                   │  │ java-app │ │ java-app │  │
                   │  │ :8080    │ │ :8080    │  │
                   │  └──────────┘ └──────────┘  │
                   │         LoadBalancer         │
                   │          Service :8080       │
                   └─────────────────────────────┘

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Tech Stack

Layer	Technology
Application	Java 8, Spring Boot 2.3
Build	Apache Maven 3.9
Unit Testing	JUnit 4
Logging	Logstash Logback Encoder
Containerization	Docker (Amazon Corretto 8 / Alpine)
Container Registry	Docker Hub
CI/CD	Jenkins + Shared Library
Orchestration	Kubernetes (Amazon EKS)
Cloud	AWS (EKS, IAM credentials)
Local Dev	Docker Compose + PostgreSQL

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Repository Structure

.
├── src/
│   ├── main/
│   │   ├── java/com/example/
│   │   │   └── Application.java        # Spring Boot entry point
│   │   └── resources/static/
│   │       └── index.html              # Static welcome page
│   └── test/
│       └── java/
│           └── AppTest.java            # JUnit test for Application
├── Dockerfile                          # Container image definition
├── docker-compose.yaml                 # Local run (app + PostgreSQL)
├── java-depl.yaml                      # Kubernetes Deployment & Service
├── Jenkinsfile                         # Active CI/CD pipeline
├── Old.Jenkinsfile.Archive             # Previous EC2-based pipeline (archived)
├── server-script.sh                    # Helper script for EC2 deployment (legacy)
└── pom.xml                             # Maven project descriptor

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CI/CD Pipeline Stages

The active pipeline is defined in Jenkinsfile and uses reusable steps from the jenkins-shared-library-master.

Stage	What Happens
test	Runs mvn test to execute all JUnit tests
Increment version	Bumps the patch version in pom.xml via incrementVersionMvn()
build jar	Packages the application with mvn package via buildJar()
build and push docker image	Builds the Docker image tagged with the new version and pushes to Docker Hub
deploy to k8s	Substitutes ${IMAGE_NAME} in java-depl.yaml and runs kubectl apply against EKS using AWS credentials
Commit incremented version	Commits and pushes the updated pom.xml back to the repository

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Kubernetes Manifest

java-depl.yaml defines two Kubernetes resources applied to EKS on every successful build:

• Deployment — runs 2 replicas of the application container, pulling the versioned image from Docker Hub using the dockerhub-key image pull secret.
• Service — a LoadBalancer-type service that exposes port 8080 publicly.

The ${IMAGE_NAME} placeholder is resolved at deploy time using envsubst.

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Docker Image

Base image : amazoncorretto:8-alpine3.17-jre
Exposed port: 8080
Entrypoint  : java -jar java-maven-app-*.jar

The image is published to Docker Hub as whispernet/java-app-k8s-cicd:<version>.

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Local Development

Run the application alongside a PostgreSQL instance using Docker Compose:

export IMAGE=whispernet/java-app-k8s-cicd:<version>
docker compose -f docker-compose.yaml up -d

The application will be available at http://localhost:8080.

Alternatively, use the helper script:

bash server-script.sh whispernet/java-app-k8s-cicd:<version>

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Prerequisites

• Jenkins with Maven (maven-3.9.11) and kubectl configured
• Jenkins credentials:
  • docker-hub — Docker Hub username/password
  • aws_access_key_id / aws_secret_accesss_key — AWS IAM credentials with EKS access (note: the credential ID contains a deliberate triple-s; it must match the name used in the Jenkinsfile exactly)
  • github-repo-access — SSH key for pushing the version commit
• EKS cluster with dockerhub-key image pull secret pre-created
• envsubst available on the Jenkins agent

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Application Endpoints

Path	Description
GET /	Serves the static index.html welcome page