zkt25/z2

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.

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🐳 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.

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🕸 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.

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🌐 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.

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⚙️ 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.

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🛠️ 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