FastAPI
The FastAPI package is supported in Python Workers.
FastAPI applications use a protocol called the Asynchronous Server Gateway Interface (ASGI) ↗. This means that FastAPI never reads from or writes to a socket itself. An ASGI application expects to be hooked up to an ASGI server, typically uvicorn ↗. The ASGI server handles all of the raw sockets on the application’s behalf.
The Workers runtime provides an ASGI server ↗ directly to your Python Worker, which lets you use FastAPI in Python Workers.
Clone the cloudflare/python-workers-examples
repository and run the FastAPI example:
git clone https://github.com/cloudflare/python-workers-examplescd python-workers-examples/03-fastapinpx wrangler@latest dev
from fastapi import FastAPI, Requestfrom pydantic import BaseModel
async def on_fetch(request, env): import asgi
return await asgi.fetch(app, request, env)
app = FastAPI()
@app.get("/")async def root(): return {"message": "Hello, World!"}
@app.get("/env")async def root(req: Request): env = req.scope["env"] return {"message": "Here is an example of getting an environment variable: " + env.MESSAGE}
class Item(BaseModel): name: str description: str | None = None price: float tax: float | None = None
@app.post("/items/")async def create_item(item: Item): return item
@app.put("/items/{item_id}")async def create_item(item_id: int, item: Item, q: str | None = None): result = {"item_id": item_id, **item.dict()} if q: result.update({"q": q}) return result
@app.get("/items/{item_id}")async def read_item(item_id: int): return {"item_id": item_id}