[BUG] auto-rewrite doesn't take openapi_prefix into account

Describe the bug

The problem is basically the one described here: https://github.com/tiangolo/fastapi/issues/51#issuecomment-522035784 My fastapi app is behind a reverse proxy that forwards all requests for /api/v1/* and rewrites them to /*. The application itself doesn’t know that but the FastAPI object which has openapi_prefix=“/api/v1”.

If I have an endpoint

@app.get("/hello")
def foo():
    return "hello"

and I query /api/v1/hello, it works fine. If I add an extra slash at the end, a redirect occurs but tries to send the user to /hello instead of /api/v1/hello. I’m not sure if it’s a bug or if I don’t use the app correctly. Maybe it would be simpler for me to make the fastapi app aware of the /api/v1 prefix and remove the rewrite rule? What do you think?

To Reproduce

Behind a reverse proxy forwarding the requests for /api/v1/* and rewriting those to /*

1. Create a file with:

from fastapi import FastAPI

app = FastAPI(openapi_prefix="/api/v1")


@app.get("/hello")
def read_root():
    return {"Hello": "World"}

1. Open the browser and call the endpoint /api/v1/hello/.
2. It returns a 404 because there is a redirect to /hello.
3. But I expected the redirect to be to /api/v1/hello.

Expected behavior

The redirection shouldn’t remove the openapi_prefix.

Environment

• OS: Linux / Windows
• FastAPI Version 0.52.0 from pip
• python 3.7.4.

[Gaasmann]

@tiangolo Hello. I just tested my app by replacing the openapi_prefix parameter by root_path on the FastAPI object: it works like a charm. I’ll close this issue. Thanks a lot!

[rkbeatss]

@tiangolo will start investigating this today