CI/CD Pipeline – Spring Boot Application 🚀

This repository demonstrates an end-to-end CI/CD pipeline using Jenkins, Docker, GitHub, Kubernetes and Argo CD (Operator-based).

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🔖 Key Concepts

CI/CD · GitOps · Release Management · Docker Image Versioning . Kubernetes Deployments · Argo CD Sync · Jenkins Pipelines

🛠️ Tech Stack & Tools

• Source Control: GitHub
• CI Tool: Jenkins (Declarative Pipeline)
• Build Tool: Maven
• Containerization: Docker
• CD Tool: Argo CD (Installed via Operator & Controllers)
• Deployment: Kubernetes

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📁 Repositories Used

Repository	Purpose	URL
myFirstProject	Spring Boot application source code	https://github.com/3034saurabhkumar/myFirstProject
CI-CD_implementation	Kubernetes manifests (deployment.yml, service.yml)	https://github.com/3034saurabhkumar/CI-CD_implementation

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🔁 CI/CD Workflow Overview

Developer Commit
      ↓
GitHub (Release Branch)
      ↓
Jenkins Pipeline
      ↓
Maven Build
      ↓
Docker Image Build & Push
      ↓
Update Deployment Repo
      ↓
Argo CD Sync
      ↓
Kubernetes Deployment

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🧩 Jenkins Pipeline Stages

1️⃣ Prepare Workspace

• Cleans old workspace
• Fresh Git checkout

2️⃣ Create Release Branch

• Creates release-<version> branch
• Pushes to GitHub using credentials

3️⃣ Build & Test (Dockerized Maven)

• Runs mvn clean package
• Generates JAR
• Stashes build artifact

4️⃣ Docker Build & Push

• Builds Docker image using JAR
• Pushes image to Docker Hub
• Image tag = release version

5️⃣ Update Deployment Repo

• Clones CI-CD_implementation
• Updates Docker image tag in deployment.yml
• Commits & pushes changes to main

6️⃣ Argo CD Deployment

• Argo CD detects Git change
• Automatically syncs to Kubernetes cluster

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🔐 Jenkins Credentials

Credential ID	Type	Usage
github-release-creds	Username + Token	GitHub push & branch creation
docker-cred	Docker Registry	Docker image push

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🐳 Docker Image Naming Convention

saurabh3034/spring-voldemort:<release-version>

Example saurabh3034/spring-voldemort:1.0.1

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🚀 Argo CD Setup

• Installed using Argo CD Operator
• CRDs and Controllers installed first
• Application configuration:
  • Repository: CI-CD_implementation
  • Branch: main
  • Path: /
• Sync Policy: Automated

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🏗️ Architecture Overview

High-Level CI/CD + GitOps Architecture

┌────────────┐
│ Developer  │
│ Git Push   │
└─────┬──────┘
      │
      ▼
┌────────────────────────┐
│ GitHub – App Repo      │
│ myFirstProject         │
│ (release-x.y.z branch) │
└─────┬──────────────────┘
      │
      ▼
┌────────────────────────┐
│ Jenkins CI             │
│------------------------│
│ • Maven Build          │
│ • Docker Image Build   │
│ • Push to Docker Hub   │
│ • Update Deploy Repo   │
└─────┬──────────────────┘
      │
      ▼
┌────────────────────────┐
│ GitHub – Deploy Repo   │
│ CI-CD_implementation   │
│ (deployment.yml)       │
└─────┬──────────────────┘
      │
      ▼
┌────────────────────────┐
│ Argo CD (Operator)     │
│ GitOps Sync Controller │
└─────┬──────────────────┘
      │
      ▼
┌────────────────────────┐
│ Kubernetes Cluster │
│ Spring Boot App │
└────────────────────────┘

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🧪 Jenkins Pipeline Explanation

❓ How does your CI/CD pipeline work?

The pipeline follows a release-based CI model with GitOps-driven CD, ensuring traceability, versioning, and automated Kubernetes deployments.

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🔹 Stage 1: Prepare Workspace

• Cleans Jenkins workspace
• Performs fresh SCM checkout

Why?

• Prevents stale artifacts
• Ensures reproducible builds

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🔹 Stage 2: Create Release Branch

• Jenkins creates release-<version> branch
• Pushes branch to GitHub using stored credentials

Why?

• Each release is immutable and traceable
• Enables safe rollback

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🔹 Stage 3: Build & Test (Dockerized Maven)

• Uses official maven Docker image
• Builds Spring Boot JAR
• Stashes artifact for later stages

Why?

• Tool isolation
• No dependency on Jenkins host setup

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🔹 Stage 4: Docker Image Build & Push

• Unstashes JAR
• Builds Docker image
• Tags image with release version
• Pushes image to Docker Hub

Why?

• Immutable versioned images
• Environment consistency

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🔹 Stage 5: Update Deployment Repository

• Jenkins updates deployment.yml
• Replaces image tag with release version
• Commits changes to deployment repository

Why?

• Git becomes the single source of truth
• Enables GitOps

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🔹 Stage 6: Continuous Deployment with Argo CD

• Argo CD watches deployment repo
• Detects Git changes
• Syncs Kubernetes automatically

Why?

• No direct kubectl apply
• Safe, auditable deployments

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🔁 Release Flow Documentation

Example Release Version: 1.0.1

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1️⃣ Trigger Jenkins Pipeline

• Manual trigger or Git push
• Provide parameter: RELEASE_VERSION=1.0.1

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2️⃣ Jenkins CI Actions

• Creates branch: release-1.0.1
• Builds JAR
• Builds Docker image: saurabh3034/spring-voldemort:1.0.1
• Pushes image to Docker Hub

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3️⃣ Deployment Repository Update

Before: image: saurabh3034/spring-voldemort:replaceImageTag After: image: saurabh3034/spring-voldemort:1.0.1 Committed to: CI-CD_implementation/main

4️⃣ Argo CD Sync

• Detects Git commit
• Syncs Kubernetes manifests
• Performs rolling update

5️⃣ Kubernetes Deployment

• Old pods terminated
• New pods created
• Zero or minimal downtime

🔙 Rollback Strategy

✅ Git Revert (Recommended): git revert <commit-id>

• Argo CD automatically rolls back the deployment.

✅ Image Rollback:

• Change image tag to previous version and commit.

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🔐 Security & Best Practices

• Jenkins credentials store for secrets
• No hardcoded tokens
• Dockerized build environments
• GitOps-based deployment control
• Immutable artifacts

🧠 One-Line Summary

“I implemented a Jenkins-based CI pipeline with GitOps-driven CD using Argo CD, enabling secure, versioned, and fully automated Kubernetes deployments.”

✅ Outcome

• Every release triggers:
  • Create Release branch
  • New Docker image build
  • Push Docker image on DockerHub
  • Updated Kubernetes manifests
  • Automatic deployment via Argo CD

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🧠 Key Concepts Covered

• Branch Strategy
• Artifact sharing in Jenkins (stash / unstash)
• Secure GitHub authentication
• Multi-repository CI/CD
• GitOps using Argo CD
• Operator-based Argo CD installation

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📌 Future Improvements

• Helm charts
• Image scanning (Trivy)
• Manual approval gates
• Slack notifications
• Ingress with TLS

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