Add Jenkins to EKS deployment README.

README.md

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+# Microservices Deployment to Amazon EKS using Jenkins
+
+This project deploys Kubernetes resources to an **Amazon EKS** cluster through a **Jenkins Pipeline**.
+
+---
+
+## Deployment Flow
+
+```text
+Git Branch -> Jenkins Pipeline -> kubectl apply -> Amazon EKS (namespace: webapps)
+```
+
+---
+
+## What This Repository Contains
+
+- `Jenkinsfile` - Jenkins pipeline for deployment and verification.
+- `deployment-service.yml` - Kubernetes Deployment/Service manifest applied to EKS.
+
+---
+
+## Prerequisites
+
+Before running deployment, make sure the following are ready:
+
+1. **AWS / EKS**
+   - EKS cluster is created and accessible.
+   - API server endpoint is reachable from Jenkins.
+2. **Jenkins**
+   - Jenkins server is running.
+   - Kubernetes CLI (`kubectl`) is installed on Jenkins agent.
+   - Required Jenkins plugin is installed for `withKubeCredentials`.
+3. **Kubernetes Access**
+   - Jenkins credential exists with ID: `k8-token`.
+   - Target namespace exists: `webapps`.
+4. **Repository**
+   - `deployment-service.yml` is present and valid.
+   - `Jenkinsfile` is in repository root.
+
+---
+
+## Jenkins Pipeline Stages in This Project
+
+The current pipeline has two deployment stages:
+
+### 1) Deploy to Kubernetes
+
+- Uses `withKubeCredentials` to authenticate to EKS.
+- Runs:
+
+```bash
+kubectl apply -f deployment-service.yml
+```
+
+### 2) Verify Deployment
+
+- Validates service visibility in namespace `webapps`.
+- Runs:
+
+```bash
+kubectl get svc -n webapps
+```
+
+---
+
+## Jenkins Job Setup (Recommended)
+
+### Option A: Pipeline Job
+
+1. Create a **Pipeline** job in Jenkins.
+2. Connect your Git repository.
+3. Set pipeline source to **Pipeline script from SCM**.
+4. Keep script path as `Jenkinsfile`.
+5. Save and run **Build Now**.
+
+### Option B: Multibranch Pipeline (Best for Multiple Branches)
+
+If you work with multiple branches, use a **Multibranch Pipeline**:
+
+1. Create **Multibranch Pipeline** job.
+2. Configure Git repository URL and credentials.
+3. Add branch discovery behavior.
+4. Set build triggers (webhook or periodic scan).
+5. Jenkins automatically builds branches that contain a `Jenkinsfile`.
+
+---
+
+## How to Deploy (Step-by-Step)
+
+1. Push latest code to your target branch.
+2. Open Jenkins job for that branch.
+3. Run pipeline build.
+4. Wait for:
+   - `Deploy To Kubernetes` stage success
+   - `verify Deployment` stage success
+5. Confirm resources in cluster:
+
+```bash
+kubectl get pods -n webapps
+kubectl get svc -n webapps
+```
+
+---
+
+## Troubleshooting
+
+- **Credential error (`k8-token`)**
+  - Recheck Jenkins credential ID and token validity.
+- **Namespace not found**
+  - Create namespace:
+    ```bash
+    kubectl create namespace webapps
+    ```
+- **Cannot connect to EKS API server**
+  - Verify EKS endpoint/network access from Jenkins.
+- **Manifest apply failed**
+  - Validate YAML syntax:
+    ```bash
+    kubectl apply --dry-run=client -f deployment-service.yml
+    ```
+
+---
+
+## Good Practices for Multi-Branch Deployments
+
+- Use separate environments per branch (`dev`, `qa`, `prod`).
+- Keep branch naming consistent (`feature/*`, `release/*`, `main`).
+- Add approvals for production branch deployments.
+- Version container images with branch + commit SHA.
+
+---
+
+## Next Improvements (Optional)
+
+- Add build and test stages before deployment.
+- Add Docker image build/push stage (ECR).
+- Add Helm/Kustomize for environment-specific configuration.
+- Add Slack/Email notifications for pipeline status.
+