Getting the authorizer name from a AWS HTTP API request

[OzyOzk]

In my lambda function, I'm using a custom router to handle the endpoints from API gateway. If I were to switch to FastAPI and Mangum, how would I access the authorizer name so that I can determine who is making the API call?

At the moment I do username = event["requestContext"]["authorizer"]["jwt"]["claims"]["username"].

Does Mangum provide this info. Looking through the code it does not seem to.

[jordaneremieff]

Hi @OzyOzk,

This information is accessible in a couple of places throughout the request cycle. The first place might be from the aws.event key in the ASGI scope if you need to access this from the application, so something like:

@app.get("/")
def home(request: Request):
    event = request.scope["aws.event"]
    username = event["requestContext"]["authorizer"]["jwt"]["claims"]["username"]
    ...

The other might be if you need to do something with it prior to application being run:

def handler(event, context):
    username = event["requestContext"]["authorizer"]["jwt"]["claims"]["username"]
    
    # Maybe you need to do something based on this information before running the application.
    if username == "my-condition":
        ...
    
    # Return the response from the application via the handler.
    asgi_handler = Mangum(app)
    response = asgi_handler(event, context) # Call the instance with the event arguments

    return response

More info in https://mangum.io/adapter/.