"Behind a Proxy" changed behaviour in the new version 0.109.0 (in Uvicorn)

[tiangolo]

Discussed in #10948

This is related to a change in Starlette and Uvicorn, making them more formally follow the ASGI spec, Starlette already does since version 0.35.0 (recently), Uvicorn needs an equivalent change, in process on: encode/uvicorn#2213

More details in the Starlette PR: encode/starlette#2400

^{Originally posted by neugeeug January 12, 2024}

First Check

• I added a very descriptive title here.
• I used the GitHub search to find a similar question and didn't find it.
• I searched the FastAPI documentation, with the integrated search.
• I already searched in Google "How to X in FastAPI" and didn't find any information.
• I already read and followed all the tutorial in the docs and didn't find an answer.
• I already checked if it is not related to FastAPI but to Pydantic.
• I already checked if it is not related to FastAPI but to Swagger UI.
• I already checked if it is not related to FastAPI but to ReDoc.

Commit to Help

• I commit to help with one of those options 👆

Example Code

uvicorn rest.main:server --host 0.0.0.0 --port 8080 --reload --root-path /proxy

server = FastAPI()

# separate spec at /v1/docs
server.mount("/v1", app_v1)
# separate spec at /v2/docs
server.mount("/v2", app_v2)

#where app_v1, app_v2 is like below
app_v1 = FastAPI(openapi_tags=tags_metadata, title="Pet store")

Description

When I run the uvicorn with the --root-path option for the above setup, the server is expecting that I include the defined root path in every request e.g:
http://localhost:8080/v2/docs is not working (404)
http://localhost:8080/proxy/v2/docs is working

IN version 0.108.0 It works as described here https://fastapi.tiangolo.com/advanced/behind-a-proxy/

Operating System

Linux

Operating System Details

No response

FastAPI Version

0.109.0

Pydantic Version

2.5.3

Python Version

3.11.5

Additional Context

No response

[RRRajput]

Just to clear it up, in 0.110.0, the behavior would be the same as 0.108.0?

[Kludex]

This was solved in the latest uvicorn: https://github.com/encode/uvicorn/releases/tag/0.26.0

[insistence]

Now using uvicorn works well, but the root_path parameter of the FastAPI object still doesn't work

[tiangolo]

Thanks @insistence, please create a new discussion question with your use case and an example that I can copy-paste to see what is not working, thanks! ☕

[insistence]

Thanks @insistence, please create a new discussion question with your use case and an example that I can copy-paste to see what is not working, thanks! ☕

Thanks for your quick reply! The new discussion question is #11033

[insistence]

import uvicorn
from fastapi import FastAPI
from fastapi.staticfiles import StaticFiles


app = FastAPI(
    root_path='/proxy'
)


@app.get("/app")
def read_main():
    return {"message": "Hello World from main app"}


app.mount("/profile", StaticFiles(directory="static"))


if __name__ == '__main__':
    uvicorn.run(app='app:app')

I already have a directory called static, which contains a file such as test.txt. When I run the code, I can only access it by http://127.0.0.1:8000/proxy/profile/test.txt in a browser. I can't access it by http://127.0.0.1:8000/profile/test.txt in a browser.
But when I run the following code, I can access it by http://127.0.0.1:8000/profile/test.txt in a browser.

import uvicorn
from fastapi import FastAPI
from fastapi.staticfiles import StaticFiles


app = FastAPI()


@app.get("/app")
def read_main():
    return {"message": "Hello World from main app"}


app.mount("/profile", StaticFiles(directory="static"))


if __name__ == '__main__':
    uvicorn.run(app='app:app', root_path='/proxy')

I would like to confirm if this is a bug in FastAPI. Can you help me? The discussion question is #11033

[RRRajput]

@insistence this looks like expected behavior because when you add a root_path it will be added before ALL the paths (including the statically mounted directories).

[insistence]

What confuses me is that the running results of these two pieces of code are inconsistent. This seems to be inconsistent with the description in the official document (https://fastapi.tiangolo.com/advanced/behind-a-proxy/#setting-the-root_path-in-the-fastapi-app). According to the official documentation, the results obtained by setting the root_path parameter to uvicorn or to FastAPI should be consistent.

[RRRajput]

Ah Indeed!

I'm sorry I missed that part. So the problem is that uvicorn's root path is not propagated to fastapi.

[insistence]

@tiangolo @Kludex Excuse me, is this a bug?

[msmitherdc]

I'm also having an issue with 026 post, see encode/uvicorn#2244 (comment)

[Mattiam2]

Issue correlated with yours.

When I pass the root_path until 0.108 the request url visible in fastapi included the root_path, from 0.109 onwards it doesn't.

Example fastapi 0.108:

Example fastapi 0.109.2:

Also the redirect from trailing slash to without trailing slash doesn't include the root_path anymore, I could fix that by passing through the proxy also the root_path but this shouldn't be correct I think.
I just have to know if this is the correct behaviour for now on or not.

[RRRajput]

@Mattiam2 can you please log an issue for this? Because I think writing here we would not get attention easily since this issue shows up as Closed.