Fastapi traces not captured for sub applications

[graham-atom]

We recently upgraded to version 2.14.4 for our fastapi application (fastapi = "0.111.0"). We were using the asgi integration with trace middleware https://ddtrace.readthedocs.io/en/stable/integrations.html#asgi but it seems to be deprecated in newer versions (even though the docs say nothing of this).

we mount a sub application like so:

from fastapi import Depends, FastAPI
app = FastAPI(
    title="API",
    version="1.0,0,
    docs_url=None,
    redoc_url=None,
    openapi_url=None,
    lifespan=lifespan,
)

from application.partner import partner_api

# "Mount" the Partner Endpoint API as a subapp at a subpath
SUB_APP_PREFIX = "/partner"
app.mount(SUB_APP_PREFIX, partner_api)

we run the application using ddtrace-run and the top level application traces appear, but none of the sub application

[wantsui]

@graham-atom - Thanks for reporting this!

Are you still encountering this error? I spent some time trying to reproduce this but was unable to. I'd like to be able to get some more details to see if this bug can be isolated. I have three questions so far:

Question 1. How do you trigger automatic instrumentation in your application?

From your statement, it seems like you were relying on the asgi middleware, but this has two approaches: in code (via app = TraceMiddleware(app)) or via ddtrace-run. Which one does this app use (code snippets would be welcome)?

Question 2. What were the components on the spans before and after the upgrade?

Our integrations should have a component tag, so if you tell us which ones the spans came from, we can use that to isolate which integration was responsible for the tracing that you previously saw.

Question 3. Which tracer version did you upgrade from?

I'm also asking this so I can see what affected changes we may have had in our release notes: https://github.com/DataDog/dd-trace-py/releases?q=fastapi&expanded=true .

Just in case these questions cannot be publicly answered due to the underlying application code, feel free to open a support ticket and link to this thread and we can keep troubleshooting from there.

Thanks in advance!