flask python app using sqlalchemy

To run your Flask Python app using SQLAlchemy on AWS Lambda, you have two main options for handling the database:

1. Use an AWS-managed Database: This involves migrating your database to an AWS-managed service like Amazon RDS, Amazon Aurora, or Amazon DynamoDB. 2. Use Your Own SQLAlchemy Database on an AWS Instance: This involves connecting your Lambda function to a database running on an EC2 instance or any other externally hosted database that you manage.

Option 1: Using an AWS-managed Database

If you decide to use an AWS-managed database, you'll need to update your DATABASE_URL to point to the new database endpoint. Here's how you can set it up:

1. Set Up an AWS RDS Instance:

• Create an Amazon RDS instance and configure it with your desired database engine (e.g., PostgreSQL, MySQL).
• Note the endpoint, username, password, and database name.

2. Update Environment Variables:

• Update your .env file or AWS Lambda environment variables to include the new DATABASE_URL for the RDS instance.

Option 2: Using Your Own SQLAlchemy Database on an AWS Instance

If you prefer to use your own database running on an AWS instance (e.g., an EC2 instance), follow these steps:

1. Ensure Network Accessibility:

• Ensure that your EC2 instance's security groups allow inbound traffic on the database port (e.g., port 5432 for PostgreSQL).
• Configure your VPC and subnet settings to allow Lambda to communicate with the EC2 instance.

2. Update Environment Variables:

• Update your .env file or AWS Lambda environment variables to include the DATABASE_URL that points to your EC2 instance's database endpoint.

AWS Lambda Configuration

Regardless of the database choice, you'll need to package your Flask app for deployment on AWS Lambda. Here's a basic example of how you can set it up:

1. Create a Deployment Package:

• Package your Flask app with its dependencies using a tool like Zappa, Serverless Framework, or AWS SAM (Serverless Application Model).

2. Configure AWS Lambda Function:

• Create an AWS Lambda function and upload your deployment package.
• Set up the necessary environment variables (including DATABASE_URL and SECRET_KEY).

Example using Zappa

Here's a simplified example using Zappa to deploy your Flask app to AWS Lambda:

1. Install Zappa:

pip install zappa

2. Initialize Zappa:

zappa init

3. Configure Zappa:

• Update zappa_settings.json to include the environment variables and AWS RDS endpoint if using an AWS-managed database.

4. Deploy with Zappa:

zappa deploy

Example Flask App Configuration

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_bcrypt import Bcrypt
from flask_login import LoginManager
import os
from dotenv import load_dotenv

load_dotenv()

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = os.getenv('DATABASE_URL')
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
app.config['SECRET_KEY'] = os.getenv('SECRET_KEY')

db = SQLAlchemy(app)
bcrypt = Bcrypt(app)
login_manager = LoginManager(app)

with app.app_context():
    db.create_all()

# Your routes and views here

if __name__ == '__main__':
    app.run(debug=True)

By following these steps, you can run your Flask app with SQLAlchemy on AWS Lambda, whether you choose to use an AWS-managed database or your own database on an AWS instance.