# Visitor Counter Application

This project demonstrates a simple web application using Apache (web server), Flask (backend) and Redis(database), deployed with Docker Compose.

## Prerequisites

- Docker Engine v20.10 or newer.
- Docker Compose v2.33.1 or newer.

## Application Description

The application consists of two services:
1. Web server (Apache) serving an HTML page.
2. Backend (flask): Handles requests to '/counter'.
2. Database (Redis) storing visitor counts persistently.

## Instructions

1. Prepare the application:
./prepare-app.sh

2. Start the application:
./start-app.sh

3. Access the application at:
http://localhost:5000
or
run "hostname -I " and copy the ip address and Access the application at :
http://[ip address you copied]:5000

4. Stop the application:
./stop-app.sh

5. Remove all resources:
./remove-app.sh

## Virtual netwok and volumes

- A default network is created by docker compose for communication between these services
- A named volum ('redis_data') ensures Redis data persists across restarts.

## Cross-Origin Resource Sharing (CORS)

Since the frontend (Apache) and backend (Flask) run on different ports, Cross-Origin Resource Sharing (CORS) has been enabled in the Flask backend using [`Flask-CORS`](https://flask-cors.readthedocs.io/en/latest/).

Specifically, the following configuration was added to the Flask backend (`app.py`):

from flask_cors import CORS
app = Flask(name)
CORS(app) # Enables CORS for all routes and origins

This allows the frontend JavaScript code to successfully communicate with the backend API without browser security restrictions.