Assignment 1 – Docker Notes App

Overview

This project is a simple Notes Application built using Docker.
It demonstrates how to run a multi-container application composed of:

• Frontend (Nginx)
• Backend (Flask REST API)
• Database (PostgreSQL)

The application allows users to:

• Add notes
• View saved notes
• Delete notes

All data is stored persistently using a Docker volume.

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Architecture

The application consists of three services:

1. Frontend

• Technology: Nginx
• Serves static HTML page
• Proxies API requests to backend
• Accessible via browser

2. Backend

• Technology: Python (Flask)
• Provides REST API:
  • GET /api/notes
  • POST /api/notes
  • DELETE /api/notes/{id}
• Connects to PostgreSQL database

3. Database

• Technology: PostgreSQL 16
• Stores notes data
• Uses persistent Docker volume

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Networking

All containers are connected via a Docker virtual network:

• Network name: zkt_net

This allows communication between:

• frontend → backend
• backend → database

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Persistent Storage

• Volume name: zkt_db_data
• Purpose: store PostgreSQL data
• Ensures data is not lost after stopping containers

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Containers Used

Container Name	Description
zkt_frontend	Nginx web server
zkt_backend	Flask API
zkt_db	PostgreSQL database

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Requirements

• Docker
• Docker Compose (plugin)
• Linux / WSL / Docker Desktop
• Web browser

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How to Run the Application

1. Prepare the application

./prepare-app.sh

### 2. Start the application 

./start-app.sh

### Then open your browser:

 http://localhost:8080 
 
 
### 3. Stop the application
./stop-app.sh

### 4. Remove the application
./remove-app.sh

## Testing the Application

-Open the web interface
-Add a note
-Verify it appears in the list
-Stop and restart the app:
./stop-app.sh
./start-app.sh
-Refresh the page

## If the note is still there → persistence works correctly

## Key Concepts Demonstrated

-Multi-container Docker application
-Docker Compose usage
-Container networking
-Persistent storage with volumes
-REST API communication
-Reverse proxy with Nginx

## Use of Artificial Intelligence

Artificial intelligence was used to:

-Design application architecture
-Generate initial code (frontend, backend, Docker config)
-Explain Docker concepts
-Assist with debugging and troubleshooting
-Prepare documentation

## Tool used:

-ChatGPT
-Gemini

## Pablo Pérez Arcas