# Calculator Web Application on Azure Kubernetes Service (AKS)

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##Application Description
This project is a simple web-based calculator that performs basic mathematical operations.
It allows users to calculate expressions and save the results. A "Show History" button displays previously saved calculations.

Built with:

- Frontend: HTML/CSS/JavaScript served via Nginx

- Backend: Flask (Python) application connected to a PostgreSQL database

- Database: PostgreSQL 15

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##Public Cloud Environment
- Provider: Microsoft Azure

- Service Used: Azure Kubernetes Service (AKS)

- Certificate Issuer: cert-manager with Let's Encrypt

- Domain: https://aliscloudwork.tech

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##Kubernetes and Cloud Components
- Deployments:
	- Frontend Deployment (Nginx server)
	- Backend Deployment (Flask server)
	- PostgreSQL Deployment (Database server)

- Services: 
	- Frontend Service (ClusterIP)
	- Backend Service (ClusterIP)
	- PostgreSQL Service (ClusterIP)
	- Ingress Controller Service (LoadBalancer)

- Ingress:
	- Ingress resource used to route traffic and enable HTTPS

- Persistent Volume:
	- PostgreSQL database uses a Persistent Volume Claim (PVC) for data persistence

- Certificate Management:
	- cert-manager with Let's Encrypt to generate HTTPS certificates automatically

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##Files Included

- prepare-app.sh: Script to deploy all Kubernetes objects and services automatically

- remove-app.sh: Script to delete all Kubernetes objects and services

- kubi/*.yaml: Kubernetes deployment, service, ingress, PVC configuration files

- backend/Dockerfile: Dockerfile for the Flask backend application

- frontend/Dockerfile: Dockerfile for the Nginx frontend application

- frontend/default.conf: Nginx configuration file for routing

- README.md: This documentation file

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##How to View and Use the Application
Open a web browser and visit: https://aliscloudwork.tech

Use the calculator to perform operations.

Click the "Show History" button to view saved calculations.

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##Running Scripts

- To deploy the application:
	- ```bash prepare-app.sh```
- To delete the application:
	- ```bash remove-app.sh```

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##External Sources and Tools Used
- DockerHub for container images

- Let's Encrypt for SSL certificates

- cert-manager for Kubernetes certificate automation

- Azure CLI for AKS management

- Official documentation for Nginx, Flask, Kubernetes YAML syntax

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##Final Notes
- HTTPS is fully functional.

- Kubernetes ensures all components are modular and recover automatically.

- Database uses persistent storage for calculation history.