Deploy FastAPI on AWS Lambda: A Step-by-Step Guide

In the world of serverless computing, AWS Lambda stands out as a powerful platform for deploying applications quickly and efficiently. FastAPI, with its high-performance capabilities and easy-to-use framework, is a perfect match for building robust APIs. In this article, we'll walk through the process of deploying a FastAPI application on AWS Lambda, step by step.

Setting Up the Environment

First, ensure you have Visual Studio Code open. Begin by installing the necessary dependencies: FastAPI, uvicorn, and Mangum, which serves as the handler for AWS Lambda. In your terminal, execute:

pip install fastapi uvicorn mangum

Next, generate a requirements.txt file to manage dependencies:

pip freeze > requirements.txt

Now, create the main application file, main.py, where we'll define our FastAPI application along with the necessary handlers:

from fastapi import FastAPI
from mangum import Mangum

app = FastAPI()

handler = Mangum(app)

@app.get("/")
async def hello():
    return {"message": "Hello!"}

Preparing for Deployment

To bundle our application for AWS Lambda, we need to package the dependencies correctly. Execute the following commands in your terminal:

pip3 install -t dependencies -r requirements.txt
cd dependencies
zip -r ../artifact.zip .
cd ..
zip -u artifact.zip main.py

Deploying to AWS Lambda

Now, let's deploy our FastAPI application to AWS Lambda:

1. Navigate to the AWS Management Console and search for Lambda.
2. Create a new function named "FastAPI".
3. Set the runtime environment to Python.
4. Enable function URLs for easy access.
5. Set authentication type to none for simplicity.
6. Create the function.

Once the function is created, upload the artifact.zip file containing your FastAPI application code and dependencies.

Configuring the Lambda Handler

To ensure proper execution, update the Lambda handler to main.handler. This points Lambda to the correct entry point of our FastAPI application.

Verifying Deployment

After saving the changes, refresh the Lambda page. You should now see a successful deployment message. Access the provided URL to test your FastAPI application deployed on AWS Lambda.

Conclusion

Congratulations! You've successfully deployed a FastAPI application on AWS Lambda. With this knowledge, you can harness the power of serverless computing for your projects. For the complete code and further details, check out the GitHub repository. Stay tuned for more insightful tutorials, and happy coding!