# Web Form Application with PostgreSQL on Kubernetes

## 📌 Application Description

This project is a simple web application built with Flask that provides a form for user input. The form collects the following data:
- Name
- Middle name
- Surname
- Age

Upon submission, the data is stored in a PostgreSQL database. A confirmation message is displayed once the data is successfully inserted.

---

## 🐳 Containers Used

1. **web-app**
   - A Python Flask-based container serving the HTML form and handling form submission.
   - Connects to the PostgreSQL container using environment variables.

2. **postgres**
   - Official PostgreSQL container used as the backend database.
   - Uses a named volume to persist data.
   - Initializes the database and the `users` table using a custom `init.sql` script.

---

## 🕸 Kubernetes Objects

| Object             | Description                                                                 |
|--------------------|-----------------------------------------------------------------------------|
| `Namespace`        | Isolates the application under `webform-app`.                               |
| `Deployment`       | Manages the Flask web app, ensuring high availability.                      |
| `StatefulSet`      | Manages the PostgreSQL database pod with persistent identity and storage.   |
| `Service`          | Exposes both the web app and PostgreSQL internally via DNS.                 |
| `PersistentVolume` | Provides physical storage for PostgreSQL data.                              |
| `PersistentVolumeClaim` | Requests storage for the StatefulSet.                                 |

---

## 🌐 Virtual Networks & Volumes

- **Virtual Networking**: Kubernetes Services provide internal DNS-based networking. The Flask app communicates with PostgreSQL using the service name `postgres` within the same namespace.
  
- **Named Volumes**:
  - A named volume is mounted at `/var/lib/postgresql/data` in the PostgreSQL container to persist database data across pod restarts.

---
## ⚙️ Container Configuration

- Flask container:
  - Dockerized using `python:3.11-slim` as the base image.
  - `flask` and `psycopg2-binary` installed.
  - `app.py` and `index.html` are copied into the container.
  - Uses port `5000`.
  
- PostgreSQL container:
  - Uses `docker-entrypoint-initdb.d/init.sql` to initialize the database (`userdb`) and create the `users` table on first run.
  - Uses environment variables for default credentials and database name.

---


## 🛠️ Instructions

### ✅ Prepare the Application

```bash
# Create namespace
kubectl apply -f kubi/namespace.yaml

# Create persistent volume and claim
kubectl apply -f kubi/pv.yaml
kubectl apply -f kubi/pvc.yaml

# Deploy PostgreSQL StatefulSet and Service
kubectl apply -f kubi/postgres-statefulset.yaml
kubectl apply -f kubi/postgres-service.yaml

# Deploy Flask web app and Service
kubectl apply -f kubi/webapp-deployment.yaml
kubectl apply -f kubi/webapp-service.yaml
```


# Run the Application
kubectl get pods -n webform-app

# You can pause the app using:
kubectl scale deployment web-app --replicas=0 -n webform-app

# Delete the app 
kubectl delete -f kubi/ --recursive

# to view the app in browser 
# find the NodePort exposed by the web app
kubectl get svc -n webform-app

# Then open broswerr and go to 
http://<your-node-ip>:<node-port>

# Since its minikube use
minikube service web-app-service -n webform-app