In this project, we'll be creating an application using FastAPI. APIs are the backbone of internet services, and I think that the FastAPI framework (released in 2018) is one of the best ways for Python users to easily make custom APIs with high performance. After that you'll learn how to deploy your FastAPI on AWS Lambda so you can host it serverlessly and not have to stress about server maintenance. This is a simple example FastAPI application that pretends to be a bookstore. Server based hosting with AWS EC2 is hard to scale out with traffic increases, difficult to do rolling updates for an app, hard to do security patching, and it's quiet expensive. AWS Lambda is a serverless compute for hosting APIs. Lambda takes care of all of the scaling, security, hosting and load balancing problems. Serverless hosting is scalable, cheap and requires low maintenance.

An Application Programming Interface (API) is an interface between your service and the rest of the world (users). Requesting a ride from Uber, booking an Airbnb, or tweeting on X are all examples of APIs in action.

Install FastAPI by running:

pip install fastapi

Use the Create It example to start a main.py file

Run the server with:

fastapi dev main.py

Create a fake database with a global variable (i.e. BOOK_DATABASE = [])

import BaseModel from pydantic library which is already installed as it is a part of fastapi

Play around with different API interfaces and check http://127.0.0.1:8000/docs#/ to see a summary of each API method

Examples:

1. "/" - Create a home index method that runs a simple health check
2. "/list-books" - returns a list of all the books existing in our database
3. "/book-by-index/{index}" - find a book by index #. Out of range will return an error message
4. "/get-random-book" - return a random book in database
5. "/get-book" - search a book by id

6. "/add-book" - input into FastAPI will add a book to your database

Magnum is an adapter for running ASGI applications in AWS Lambda to handle function URL, API Gateway, and more.

Install Magnum:

pip install magnum

Wrap your entire app with a Mangum handler:

from mangum import Mangum

app = FastAPI()
handler = Mangum(app)

We'll also need to install the dependencies into a local directory so we can zip it up.

pip install -t lib -r requirements.txt

Change directory to the library folder:

cd lib

We now need to zip it up:

Compress-Archive -Path * -DestinationPath ../lambda_function.zip

Change directory back to the project folder:

cd ..

Now add our FastAPI file and the JSON file.

Compress-Archive -Path main.py -Update -DestinationPath lambda_function.zip
Compress-Archive -Path books.json -Update -DestinationPath lambda_function.zip

Tutorial videos:

1. FastAPI Python Tutorial - Learn How to Build a REST API
2. Deploy FastAPI on AWS Lambda ⚡ Serverless hosting!