zkt25/Z2

To-Do List Application on Kubernetes

Application Description

This is a simple To-Do List web application that allows users to:

• Add new tasks
• Mark tasks as completed
• Delete tasks
• Filter tasks by their status (All, Active, Completed)
• Reorder tasks using drag-and-drop functionality

The application uses local storage to persist tasks and allows users to manage their daily tasks efficiently.

Container Images Used

1. todo-web-app:latest:

   • Custom image based on nginx:alpine
   • Contains the static web files (HTML, CSS, JavaScript) for the To-Do List application
   • Serves the web interface on port 80

2. redis:alpine:

   • Official Redis image based on Alpine Linux
   • Used in the StatefulSet for data persistence
   • Stores task data on a persistent volume
   • Runs on port 6379

Kubernetes Objects

1. Namespace (todo-app-ns):

   • Isolates all the application resources in a dedicated namespace

2. Deployment (todo-web-app):

   • Manages the web application containers
   • Maintains 2 replicas for high availability
   • Defines resource limits and requests

3. StatefulSet (todo-data-manager):

   • Manages Redis instances for data persistence
   • Uses persistent storage to maintain task data
   • Ensures data consistency during pod restarts

4. PersistentVolume (todo-app-pv):

   • Provides storage resources for the application
   • Uses local storage on the host at /mnt/data/todo-app
   • 1GB capacity for storing task data

5. PersistentVolumeClaim (todo-app-pvc):

   • Claims storage from the PersistentVolume
   • Used by the StatefulSet for data persistence

6. Services:

   • todo-web-service: NodePort service exposing the web application
   • todo-data-service: Headless service for the StatefulSet

Network and Volume Configuration

Networks

• The application components communicate within the Kubernetes cluster using services
• todo-web-service exposes the web interface externally using NodePort
• todo-data-service provides internal DNS-based service discovery for the StatefulSet

Volumes

• The application uses a persistent volume mounted at /mnt/data/todo-app on the host
• This volume is mounted into the Redis container at /data to persist task data
• The volume uses the manual storage class with ReadWriteOnce access mode

Container Configuration

Web Application Container

• Based on nginx:alpine
• Configured to serve static content from /usr/share/nginx/html
• Resource limits: 500m CPU, 256Mi memory
• Resource requests: 100m CPU, 128Mi memory

Redis Container

• Based on redis:alpine
• Data directory mounted to persistent storage
• Resource limits: 300m CPU, 256Mi memory
• Resource requests: 100m CPU, 128Mi memory

How to Use the Application

Prerequisites

• Kubernetes cluster (Minikube or similar)
• kubectl configured to communicate with your cluster
• Docker for building the application image

Prepare the Application

1. Clone this repository
2. Run the preparation script:

   chmod +x prepare-app.sh
   ./prepare-app.sh
   

Start the Application

1. Run the start script:

   chmod +x start-app.sh
   ./start-app.sh
   

2. The script will display the URL to access the application

Stop the Application

1. Run the stop script:

   chmod +x stop-app.sh
   ./stop-app.sh
   

Accessing the Web Interface

1. After starting the application, note the NodePort displayed in the terminal
2. Open your web browser and navigate to http://localhost:<NodePort>
3. You should see the To-Do List application interface
4. Start adding tasks, marking them as completed, or deleting them as needed

Troubleshooting

• If pods aren't starting, check the pod status: kubectl get pods -n todo-app-ns
• For detailed pod issues: kubectl describe pod <pod-name> -n todo-app-ns
• To view logs: kubectl logs <pod-name> -n todo-app-ns