This example shows how to use Lambda Web Adapter to run a FastAPI application on managed python runtime.

We add Lambda Web Adapter layer to the function and configure wrapper script.

1. attach Lambda Adapter layer to your function. This layer containers Lambda Adapter binary and a wrapper script.
   1. x86_64: arn:aws:lambda:${AWS::Region}:753240598075:layer:LambdaAdapterLayerX86:20
   2. arm64: arn:aws:lambda:${AWS::Region}:753240598075:layer:LambdaAdapterLayerArm64:20
2. configure Lambda environment variable AWS_LAMBDA_EXEC_WRAPPER to /opt/bootstrap. This is a wrapper script included in the layer.
3. set function handler to a startup command: run.sh. The wrapper script will execute this command to boot up your application.

To get more information of Wrapper script, please read Lambda documentation here.

Run the following commands to build and deploy the application to lambda.

sam build --use-container
sam deploy --guided

When the deployment completes, take note of FastAPI's Value. It is the API Gateway endpoint URL.

Open FastAPI's URL in a browser, you should see "hello world" on the page.