zkt25/z2-failed/README.md

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.