# Calculator Web Application on Azure Kubernetes Service (AKS)

---

## 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

---

## Public Cloud Environment
- Provider: Microsoft Azure
- Service Used: Azure Kubernetes Service (AKS)
- Certificate Issuer: cert-manager with Let's Encrypt
- Domain: https://aliscloudwork.tech

---

## 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

---

## Azure CLI Setup Steps

### 1. Create a Resource Group
```bash
az group create --name aks-calculator-rg --location westeurope```
---
2. Create AKS Cluster (basic version, no AGIC yet)
az aks create \
  --resource-group aks-calculator-rg \
  --name calculatorAKS \
  --node-count 1 \
  --enable-managed-identity \
  --generate-ssh-keys
---

3. Connect kubectl to Your AKS Cluster

az aks get-credentials --resource-group aks-calculator-rg --name calculatorAKS
kubectl get nodes
---

Example output:

shane@Ali-DESKTOP:~/assinments/cal$ kubectl get nodes
NAME                                STATUS   ROLES    AGE     VERSION
aks-nodepool1-21170036-vmss000000   Ready    <none>   5m42s   v1.31.7
---
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

---

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.

---

Running Scripts
To deploy the application:
- bash prepare-app.sh

To delete the application:
- bash remove-app.sh

---

xternal 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


---


Final Notes
HTTPS is fully functional.

Kubernetes ensures all components are modular and recover automatically.

Database uses persistent storage for calculation history.