Get origin URL in FastAPI

Question

Is it possible to get the URL that a request came from in FastAPI?

For example, if I have an endpoint that is requested at api.mysite.com/endpoint and a request is made to this endpoint from www.othersite.com , is there a way that I can retrieve the string "www.othersite.com" in my endpoint function?

Answer 1

The premise of the question, which could be formulated as

a server can identify the URL from where a request came

is misguided. True, some HTTP requests (especially some of the requests issued by browsers) carry an Origin header and/or a Referer [sic] header . Also, the Forwarded header , if present, contains information about where the request was issued. However, nothing in the HTTP specification requires that requests in general advertise where they came from.

Therefore, whether with FastAPI or some other server technology, there's no definite way of knowing where a request came from.

Answer 2

As per FastAPI documentation , and hence Starlette's :

Let's imagine you want to get the client's IP address/host inside of your path operation function.

@app.get("/items/{item_id}")
def read_root(item_id: str, request: Request):
    client_host = request.client.host
    return {"client_host": client_host, "item_id": item_id}

Please note, as pointed out by others, if you use nginx, you need to add headers to the nginx request to handle that data.