How to Deploy FastAPI Applications on AWS

FastAPI is a modern, fast (high-performance), web framework for building APIs with Python based on standard Python type hints. Amazon Web Services (AWS) is a comprehensive, evolving cloud computing platform that provides a wide range of services. Deploying a FastAPI application on AWS allows you to take advantage of AWS’s scalability, reliability, and security features. This blog will guide you through the process of deploying a FastAPI application on AWS, covering fundamental concepts, usage methods, common practices, and best practices.

Table of Contents

  1. Prerequisites
  2. Fundamental Concepts
  3. Creating a FastAPI Application
  4. Packaging the Application
  5. AWS Services for Deployment
    • Elastic Beanstalk
    • AWS Lambda and API Gateway
  6. Deployment Steps
    • Elastic Beanstalk Deployment
    • Lambda and API Gateway Deployment
  7. Common Practices
  8. Best Practices
  9. Conclusion
  10. References

Prerequisites

  • Basic knowledge of Python and FastAPI.
  • An AWS account.
  • AWS CLI installed and configured on your local machine.
  • Python 3.6 or higher installed.

Fundamental Concepts

FastAPI

FastAPI is built on top of Starlette for the web parts and Pydantic for the data parts. It uses Python type hints to validate, serialize, and deserialize data, and it generates OpenAPI schemas automatically.

AWS

AWS offers multiple services that can be used to deploy FastAPI applications:

  • Elastic Beanstalk: A fully managed service that makes it easy to deploy, manage, and scale your web applications. It automatically handles the underlying infrastructure, such as EC2 instances, load balancers, and auto - scaling.
  • AWS Lambda: A serverless compute service that lets you run code without provisioning or managing servers. You can write your FastAPI application as a Lambda function and use API Gateway to expose it as an API.

Creating a FastAPI Application

Let’s create a simple FastAPI application. Create a new directory and a Python file named main.py:

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: str = None):
    return {"item_id": item_id, "q": q}

To run this application locally, install FastAPI and Uvicorn (a fast ASGI server for Python):

pip install fastapi uvicorn

Then start the server:

uvicorn main:app --reload

You can access the application at http://127.0.0.1:8000.

Packaging the Application

Create a requirements.txt file in the same directory as main.py to list all the dependencies:

fastapi
uvicorn

You can create a zip file containing main.py and requirements.txt for deployment. On Linux or macOS, you can use the following command:

zip -r fastapi_app.zip main.py requirements.txt

AWS Services for Deployment

Elastic Beanstalk

Elastic Beanstalk is a great choice if you want a fully managed platform to deploy your application without having to worry about the underlying infrastructure details. It supports multiple programming languages, including Python.

AWS Lambda and API Gateway

AWS Lambda allows you to run your code without managing servers. API Gateway is used to create, publish, maintain, monitor, and secure APIs at any scale. Combining Lambda and API Gateway is suitable for serverless deployments.

Deployment Steps

Elastic Beanstalk Deployment

  1. Create an Elastic Beanstalk environment:
    • Open the Elastic Beanstalk console in the AWS Management Console.
    • Click “Create a new environment” and select “Web server environment”.
    • Choose “Python” as the platform.
    • Upload the fastapi_app.zip file you created earlier.
    • Provide a name for your environment and click “Create environment”.
  2. Configure the environment:
    • Elastic Beanstalk will automatically detect your application and start the deployment process.
    • You can configure additional settings such as environment variables, scaling options, and security groups.

Lambda and API Gateway Deployment

  1. Create a Lambda function:
    • Open the AWS Lambda console.
    • Click “Create function”.
    • Select “Author from scratch”.
    • Provide a name for your function, choose a runtime (Python 3.x), and create a new execution role.
    • Upload the fastapi_app.zip file to the Lambda function.
    • Configure the handler to point to the FastAPI application entry point (e.g., main.handler). You may need to adjust your code to work as a Lambda function. Here is an example of a Lambda - compatible FastAPI application:
import json
from fastapi import FastAPI
from mangum import Mangum

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


handler = Mangum(app)
  1. Create an API in API Gateway:
    • Open the API Gateway console.
    • Click “Create API”.
    • Select “REST API” and choose “New API”.
    • Provide a name for your API and click “Create API”.
  2. Integrate the API with the Lambda function:
    • Create a resource and a method (e.g., GET) in the API Gateway.
    • Set the integration type to “Lambda Function” and select the Lambda function you created earlier.
    • Deploy the API to a stage.

Common Practices

  • Environment Variables: Use environment variables to store sensitive information such as database connection strings, API keys, etc. In Elastic Beanstalk, you can set environment variables in the console. In Lambda, you can set them in the function configuration.
  • Logging and Monitoring: Enable logging and monitoring for your application. Elastic Beanstalk provides built - in logging and monitoring through CloudWatch. For Lambda, CloudWatch also provides detailed logs and metrics.

Best Practices

  • Security: Follow AWS security best practices, such as using IAM roles with the least privilege, encrypting data at rest and in transit, and enabling security groups.
  • Scalability: Design your application to be scalable. Elastic Beanstalk and Lambda both support auto - scaling. Configure the scaling options based on your application’s traffic patterns.
  • Testing: Test your application thoroughly before deployment. You can use unit tests, integration tests, and end - to - end tests to ensure the quality of your application.

Conclusion

Deploying a FastAPI application on AWS can provide you with a scalable, reliable, and secure platform for your web API. Whether you choose Elastic Beanstalk for a fully managed solution or Lambda and API Gateway for a serverless approach, AWS offers the tools and services to meet your needs. By following the steps and best practices outlined in this blog, you can successfully deploy your FastAPI application on AWS.

References