# Contact List Web Application on Kubernetes

## Description

A simple web-based contact list app with name and number fields, using Node.js/Express and MongoDB. Data is persisted in MongoDB.

## Containers

- **contact-app**: Node.js/Express web server serving the frontend and API.
- **mongo**: Official MongoDB container for data storage.

## Kubernetes Objects

- **Namespace**: `contact-app` — all resources are grouped here.
- **Deployment**: Runs the Node.js web app.
- **StatefulSet**: Runs MongoDB with persistent storage.
- **PersistentVolume/PersistentVolumeClaim**: Stores MongoDB data.
- **Service**: 
  - `contact-app`: Exposes the web app on a NodePort.
  - `mongo`: Headless service for MongoDB.

## Virtual Networks and Volumes

- **Headless Service**: For MongoDB pod DNS discovery.
- **Named Volume**: `/data/mongo` on the host, mounted to MongoDB for persistence.

## Container Configuration

- The Node.js app uses the `MONGODB_URI` environment variable to connect to MongoDB.
- MongoDB uses a persistent volume for `/data/db`.

## Instructions

### Prepare

```bash
chmod +x prepare-app.sh start-app.sh stop-app.sh
./prepare-app.sh
```

### Run

```bash
./start-app.sh
```

### Access the App

1. Get the NodePort:
   ```bash
   kubectl -n contact-app get service contact-app
   ```
2. Open in browser:  
   `http://<minikube_ip>:<node_port>`
   - Get Minikube IP: `minikube ip`

### Pause/Stop

```bash
./stop-app.sh
```

### Delete Volumes (optional)

```bash
rm -rf /data/mongo
```

---

## View the Application

- Open the NodePort URL in your browser.
- Add and view contacts via the web UI.

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## Notes

- Make sure Docker is running and Minikube is started.
- All kubectl commands assume your context is set to Minikube.