The root_path is missing from the redirects from an url with trailing slash to the same url without it

[Mattiam2]

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Example Code

from fastapi import FastAPI

app = FastAPI(root_path="/wms")


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

Description

The program runs in gunicorn (using the uvicorn worker class) behind a nginx proxy which strips away the root_path (as described in Behind a proxy).

Before fastapi 0.109 an URL with a trailing slash (ex. https://127.0.0.1/wms/hello/) would be redirected to the corresponding URL without the trailing slash (ex. https://127.0.0.1/wms/hello) as expected.

From fastapi 0.109 the redirect no more includes the root_path, so from https://127.0.0.1/wms/hello/ the application redirects to https://127.0.0.1/hello which results in a 404 Not Found error.

Here the headers of the redirect request:

I think the issue is correlated to this one but it's not really the same.

Operating System

Linux

Operating System Details

The server runs on Redhat 8.7

FastAPI Version

0.109.2

Pydantic Version

2.6.1

Python Version

3.9.13

Additional Context

No response

[Kludex]

What's the uvicorn version? If it's not the latest one, try it.

[Mattiam2]

I'm using uvicorn 0.27.1 which is the latest one

[Mattiam2]

I think I've found where the issue came from.
In starlette 0.35.0 it was changed the constructor of the URL data structure removing the root_path from the path variable (you can see the change here).
Is this the right behaviour? It doesn't seem right to me, by the way I'll open an issue on Starlette.