# Visitor Counter Application

## Description of the Application
This application is designed to count the number of visits to a webpage. It utilizes Flask for the backend, Apache for serving static web content, and Redis for storing visitor counts.

## List of Containers Used

- **Backend Container**: Built using Flask, this container handles API requests and updates visitor counts in Redis.
- **Web Container**: Built using Apache, this container serves static HTML content.
- **Redis Container**: Uses the official Redis image to store visitor counts persistently.

## List of Kubernetes Objects

- **Deployments**:
  - **Backend Deployment**: Manages the backend Flask application.
  - **Web Deployment**: Manages the web Apache server.
- **Services**:
  - **Backend Service**: Exposes the backend application on a specific port.
  - **Web Service**: Exposes the web server on a specific port.
  - **Redis Service**: Provides access to the Redis database.
- **StatefulSet**:
  - **Redis StatefulSet**: Ensures persistent storage for Redis data.
- **PersistentVolumeClaim (PVC)** and **PersistentVolume (PV)**:
  - Used for providing persistent storage to Redis.

## Virtual Networks and Named Volumes

- **Virtual Networks**: Kubernetes automatically manages pod-to-pod communication within a cluster.
- **Named Volumes**: Used for persistent storage in Redis, ensuring data is retained across pod restarts.

## Container Configuration

- **Backend Container**: Configured to listen on port 5000 and connect to Redis for storing visitor counts.
- **Web Container**: Configured to serve static HTML content on port 80.
- **Redis Container**: Configured to store data persistently using a PersistentVolumeClaim.

## Instructions to Prepare, Run, Pause, and Delete the Application

1. **Prepare the Application**:
   Run the `prepare-app.sh` script to build Docker images and load them into Minikube.

./prepare-app.sh


2. **Run the Application**:
Run the `start-app.sh` script to create all necessary Kubernetes objects and start the application.
./start-app.sh


3. **Pause the Application**:
You can pause the application by scaling down deployments to zero replicas:

kubectl scale deployment backend-deployment --replicas=0
kubectl scale deployment web-deployment --replicas=0


4. **Delete the Application**:
Run the `stop-app.sh` script to delete all Kubernetes objects and stop the application.
./stop-app.sh


## Instructions to View the Application on the Web

1. **Access the Web Service**:
Use Minikube to access the web service:

minikube service web-service --url

This will output a URL that you can use to view the application in your web browser by ctrl+clicking on the link.