Documentation for FastAPI/Starlette ASGI not correct

Environment

How do you use Sentry? Sentry SaaS (sentry.io)

Which SDK and version? python sentry-sdk==1.4.3 via pipenv

Steps to Reproduce

• Followed the installation instructions in an FastAPI app
• Run a HTTP request against the API

Expected Result

Sentry logging errors

Actual Result

AttributeError: 'SentryAsgiMiddleware' object has no attribute 'add_middleware'

Analysis

I think the issue can be fixed by changing the way the middleware is added:

app = FastAPI()
app.add_middleware(SentryAsgiMiddleware)

That being said, I am not getting errors logged when I call a route that runs raise HTTPException(status_code=500, detail="Test"). So I think the middleware is still not working.

[AbhiPrasad]

Thank you for raising an issue. You’ll need to use the ASGI middleware in conjugation with app.exception_handler. We have to improve our documentation here - and in general have a better story around FastAPI.

app = FastAPI()

# Uncaught exceptions (like `raise Exception`) should propagate correctly
# to Sentry's error handler
# Middleware will also enable Sentry performance monitoring to work as expected
app.add_middleware(SentryAsgiMiddleware)

# To catch raised `HTTPException` exceptions as per:
# https://fastapi.tiangolo.com/tutorial/handling-errors/
#
# You might have to add something similar for `RequestValidationError`
@app.exception_handler(HTTPException)
async def custom_http_exception_handler(request, e):
    with sentry_sdk.configure_scope() as scope:
        scope.set_context("request", request)
        sentry_sdk.capture_exception(e)

    return await http_exception_handler(request, e)

For the future, we probably should just monkey patch the exception_handler so we take care of this out of the box.

[lsmith77]

so if create an exception that isn’t caught by FastAPI (f.e. raise ValueError("nope")) it seems to log it properly. So am I wrong to assume that HTTPException should be converted or does this indeed just show that the middleware isn’t properly installed?