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

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

# 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://:

Since its minikube use

minikube service web-app-service -n webform-app

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