Adapter

The heart of Vellex is the adapter class. It is a configurable wrapper that allows any ASGI application (or framework) to run in GCP Cloud Functions deployment. The adapter accepts a number of keyword arguments to configure settings related to HTTP responses, ASGI lifespan, and Base path configuration.

handler = Vellox(
    app,
    lifespan="auto",
    base_path="/",
    custom_handlers=None,
    text_mime_types=None,
    exclude_headers=None
)

All arguments are optional.

Configuring an adapter instance

class vellox.adapter.Vellox(app, lifespan='auto', base_path='/', custom_handlers=None, text_mime_types=None, exclude_headers=None)

Creating an Cloud Functions handler

The adapter can be used to wrap any application without referencing the underlying methods. It defines a __call__ method that allows the class instance to be used as an Cloud Functions handler function.

from fastapi import FastAPI
from vellox import Vellox

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}

vellox = Vellox(app=app, lifespan="off")

def handler(request):
    return vellox(request)

However, this is just one convention, you may also intercept events and construct the adapter instance separately. This may be useful if you need to implement custom event handling. The handler in the example above could be replaced with a function.

def handler(request : flask.Request):
    if request.method not in ["GET", "POST"]:
        # Do something or return, etc.
        return

    asgi_handler = Vellox(app)
    response = vellox(request) # Call the instance with the event arguments

    return response

Retrieving the AWS event and context

The GCP Cloud Functions handler request arguments are made available to an ASGI application in the ASGI connection scope.

scope['flask.request']

For example, if you're using FastAPI it can be retrieved from the scope attribute of the request object.

from fastapi import FastAPI
from vellox import Vellox
from starlette.requests import Request

app = FastAPI()


@app.get("/")
def hello(request: Request):
    return {"aws_event": request.scope['flask.request']}

vellox = Vellox(app=app)

def handler(request):
    return vellox(request)