Building an APP with NOSQL Database

Introduction

DynamoDB

DynamoDB is a fully managed NoSQL database service provided by Amazon Web Services (AWS). It is designed to handle large amounts of data and provides fast and predictable performance with seamless scalability.

Managed Service: DynamoDB is fully managed, meaning that AWS handles operational tasks such as hardware provisioning, setup, configuration, and backups.
NoSQL Database: It is a NoSQL database, allowing for flexible data models and horizontal scaling, making it suitable for applications with varying data structures.
Performance: DynamoDB offers single-digit millisecond response times, ideal for applications that require high-speed data access.
Scalability: The service can automatically scale up and down to accommodate varying workloads, allowing applications to handle large volumes of data and traffic without manual intervention.
Global Tables: DynamoDB supports global tables, enabling multi-region, fully replicated tables that provide low-latency access to data across different geographical locations.
Integration with AWS Services: DynamoDB integrates seamlessly with other AWS services such as Lambda, API Gateway, and S3, allowing for the development of complex applications in the cloud.
Security and Compliance: It provides built-in security features, including encryption at rest and in transit, and supports AWS Identity and Access Management (IAM) for fine-grained access control.

Running Local DynamoDB

We have to go to this URL and download the zip
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DynamoDBLocal.DownloadingAndRunning.html

After you download the archive, extract the contents and copy the extracted directory to a location of your choice.

To start DynamoDB on your computer, open a command prompt window, navigate to the directory where you extracted DynamoDBLocal.jar, and enter the following command.

java -Djava.library.path=./DynamoDBLocal_lib -jar DynamoDBLocal.jar -sharedDb

Code Example

Now we are going to test a simple web application, using python and boto3 libraries with flask.

Requirements

Python
Boto3, Flask
Docker
DynamoDBLocal files ### Python Code
Project structure

EjemploDynamoDB/
└── app/
│    ├── templates/
│    │   ├── index.html
│    │   └── add_item.html
│    ├── app.py
└── docker-compose.yml
└── Dockerfile

from flask import Flask, render_template, request, redirect, url_for
import boto3
from botocore.exceptions import ClientError

app = Flask(__name__)


dynamodb = boto3.resource(
    'dynamodb',
    endpoint_url="http://dynamodb-local:8000",
    region_name="us-west-2",
    aws_access_key_id="DUMMYIDEXAMPLE",
    aws_secret_access_key="DUMMYEXAMPLEKEY"
)

table_name = "TestTable"


@app.route('/')
def index():
    table = dynamodb.Table(table_name)
    try:
        response = table.scan()
        items = response.get('Items', [])
        return render_template('index.html', items=items)
    except ClientError as e:
        return f"Error: {e}"


@app.route('/add', methods=['GET', 'POST'])
def add_item():
    if request.method == 'POST':
        id = request.form['id']
        nombre = request.form['nombre']
        valor = request.form['valor']
        table = dynamodb.Table(table_name)
        item = {'id': id, 'nombre': nombre, 'valor': valor}
        try:
            table.put_item(Item=item)
            return redirect(url_for('index'))
        except ClientError as e:
            return f"Error: {e}"
    return render_template('add_item.html')

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=8080)

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Lista de Elementos</title>
</head>
<body>
    <h1>Elementos en DynamoDB</h1>
    <a href="{{ url_for('add_item') }}">Agregar nuevo elemento</a>
    <ul>
        {% for item in items %}
            <li>{{ item['id'] }} - {{ item['nombre'] }}: {{ item['valor'] }}</li>
        {% endfor %}
    </ul>
</body>
</html>

add_item.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Lista de Elementos</title>
</head>
<body>
    <h1>Elementos en DynamoDB</h1>
    <a href="{{ url_for('add_item') }}">Agregar nuevo elemento</a>
    <ul>
        {% for item in items %}
            <li>{{ item['id'] }} - {{ item['nombre'] }}: {{ item['valor'] }}</li>
        {% endfor %}
    </ul>
</body>
</html>

dockerfile


FROM python:3.9-slim


WORKDIR /app


COPY app/app.py /app/app.py
COPY app/templates /app/templates


RUN pip install boto3 flask


CMD ["python", "app.py"]

dockerfile


version: '3.8'
services:
  dynamodb-local:
    image: "amazon/dynamodb-local:latest"
    container_name: dynamodb-local
    command: "-jar DynamoDBLocal.jar -sharedDb -dbPath ./data"
    ports:
      - "8000:8000"
    volumes:
      - "./docker/dynamodb:/home/dynamodblocal/data"
    working_dir: /home/dynamodblocal

  app-python:
    build:
      context: .
      dockerfile: Dockerfile  # Dockerfile en la raíz del proyecto
    container_name: app-python
    depends_on:
      - dynamodb-local
    environment:
      AWS_ACCESS_KEY_ID: 'DUMMYIDEXAMPLE'
      AWS_SECRET_ACCESS_KEY: 'DUMMYEXAMPLEKEY'
    ports:
      - "8080:8080"
    command: >
      sh -c "pip install boto3 flask && python app.py"