zkt25/z1/README.md

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'.
3. 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.

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.