Quickstart

This page shows a server which answers from both frameworks, and then the command line server.

Install the package

pip install aiohttp-asgi

FastAPI and Starlette are not dependencies of this package. Install the framework of the ASGI application separately:

pip install fastapi

Serve an ASGI application beside aiohttp handlers

Create example.py:

from aiohttp import web
from fastapi import FastAPI

from aiohttp_asgi import ASGIResource

asgi_app = FastAPI()


@asgi_app.get("/users/{user_id}")
async def get_user(user_id: int):
    return {"user_id": user_id}


async def aiohttp_handler(request: web.Request) -> web.Response:
    return web.Response(text="This handler is an aiohttp handler")


aiohttp_app = web.Application()

# The ASGI application answers under the /api prefix.
asgi_resource = ASGIResource(asgi_app, root_path="/api")
aiohttp_app.router.register_resource(asgi_resource)

# The aiohttp routes stay outside of that prefix.
aiohttp_app.router.add_get("/ping", aiohttp_handler)

# The ASGI application gets the startup and shutdown events.
asgi_resource.lifespan_mount(aiohttp_app)


if __name__ == "__main__":
    web.run_app(aiohttp_app)

Start it:

python example.py

Both frameworks now answer on the same port:

curl http://127.0.0.1:8080/api/users/42
# {"user_id":42}

curl http://127.0.0.1:8080/ping
# This handler is an aiohttp handler

Important

The resource takes every request which starts with root_path, therefore the aiohttp routes must stay outside of that prefix. The default root_path is /, which takes every request; in that case add the aiohttp routes before the resource. The hybrid application page uses this order.

Serve an ASGI application without aiohttp code

The package installs the aiohttp-asgi command. It takes the application in the module_name:attribute format:

# test_app.py
from starlette.applications import Starlette
from starlette.responses import JSONResponse
from starlette.routing import Route


async def homepage(request):
    return JSONResponse({"hello": "world"})


application = Starlette(debug=True, routes=[Route("/", endpoint=homepage)])

aiohttp-asgi --address 127.0.0.1 --port 8080 test_app:application

The same server starts through the module:

python -m aiohttp_asgi --address 127.0.0.1 --port 8080 test_app:application

The command line server page describes the worker processes and the event loop options.

Next steps