# Notes Application - Docker & Kubernetes Deployment

## Overview

This project is a Notes Application deployed using Docker and Kubernetes (MicroK8s).
The application allows users to:

- Create notes
- Delete notes
- Upload files
- Download files

It follows a 3-tier architecture:

- Frontend (Nginx)
- Backend (Node.js)
- Database (MongoDB)

## Architecture

```
User -> Frontend (Nginx) -> Backend (Node.js) -> MongoDB
```

## Containers

### Frontend

- Image: `nginx:alpine`
- Role: Serves static UI
- Port: `80`

### Backend

- Image: `node:18`
- Role: API server (handles notes & files)
- Port: `3000`

### Database

- Image: `mongo:6.0`
- Role: Stores notes and file data
- Port: `27017`

## Kubernetes Resources

- Namespace: `z2`
- Deployments:
  - `frontend`
  - `backend`
- StatefulSet:
  - `mongo`
- Services:
  - `frontend` (NodePort -> 30007)
  - `backend` (ClusterIP)
  - `mongo` (Headless Service)

## Storage

- Persistent Volume Claim: `mongo-storage`
- Size: `1Gi`
- Mount path: `/data/db`
- Purpose: Store MongoDB data persistently

## Setup Instructions

### 1. Prepare Application

```bash
./prepare-app.sh
```

- Builds Docker images
- Loads them into MicroK8s

### 2. Start Application

```bash
./start-app.sh
```

- Deploys Kubernetes resources
- Starts all services

### 3. Stop Application

```bash
./stop-app.sh
```

- Stops running pods
- Keeps configuration

### 4. Delete Application

```bash
microk8s kubectl delete all --all -n z2
microk8s kubectl delete pvc --all -n z2
```

- Removes everything including database

## Access Application

Open in browser:

```
http://<server-ip>:30007
```

Example:

```
http://147.232.204.210:30007
```

## Useful Commands

Check pods:

```bash
microk8s kubectl get pods -n z2
```

Check services:

```bash
microk8s kubectl get svc -n z2
```

View logs:

```bash
microk8s kubectl logs <pod-name> -n z2
```

## Common Issues

### Mongo Crash (version error)

Fix:

```bash
microk8s kubectl delete pvc --all -n z2
```

### Frontend shows "Welcome to nginx"

Fix:

- Ensure `index.html` is copied in Dockerfile
- Rebuild using:

```bash
./prepare-app.sh
```

## Honesty Statement

This project was developed with the assistance of AI tools (such as ChatGPT) for:

- Debugging errors
- Understanding Kubernetes concepts
- Identifying fixes for deployment issues

All configurations, testing, and final implementation were completed independently, and the AI was used strictly as a learning aid.