fix(fastapi): apply tracing to user middlewares in fastapi [backport 1.8] #5084
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mabdinur
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Feb 9, 2023
mabdinur
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tests/snapshots/tests.contrib.fastapi.test_fastapi.test_tracing_in_middleware.json
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mabdinur
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Feb 9, 2023
## Description Resolve: #4397 In Starlette and FastAPI applications the last middleware configured is the first one called ([here](https://github.com/encode/starlette/blob/0.21.0/starlette/applications.py#L168)). The fastapi trace middleware is applied when a fastapi application is created ([fastapi.FastAPI()](https://github.com/DataDog/dd-trace-py/blob/a21c8dbc433577245f5c145fd46f2a3dc4540402/ddtrace/contrib/fastapi/patch.py#L38)). If another middleware is configured after an application is initialized it will not be traced. Here's an example of a fastapi middleware being configured after `fastapi.FastApi()` is called: https://fastapi.tiangolo.com/tutorial/middleware/#create-a-middleware. Note - This PR only ensures Fastapi middlewares are traced. Supporting all starlette middlewares is out of scope. ## Reviewer Checklist - [ ] Title is accurate. - [ ] Description motivates each change. - [ ] No unnecessary changes were introduced in this PR. - [ ] Avoid breaking [API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces) changes unless absolutely necessary. - [ ] Tests provided or description of manual testing performed is included in the code or PR. - [ ] Release note has been added for fixes and features, or else `changelog/no-changelog` label added. - [ ] All relevant GitHub issues are correctly linked. - [ ] Backports are identified and tagged with Mergifyio. Co-authored-by: Brett Langdon <[email protected]> (cherry picked from commit b5a4511)
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emmettbutler
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Feb 14, 2023
Yun-Kim
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Codecov Report
@@ Coverage Diff @@
## 1.8 #5084 +/- ##
==========================================
+ Coverage 74.88% 74.89% +0.01%
==========================================
Files 816 816
Lines 63501 63513 +12
==========================================
+ Hits 47552 47569 +17
+ Misses 15949 15944 -5
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For anyone who also finds their way here, this was released in ddtrace 1.9 |
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Backport b5a4511 from #4478 to 1.8.
Description
Resolve: #4397
In Starlette and FastAPI applications the last middleware configured is the first one called (here). The fastapi trace middleware is applied when a fastapi application is created (fastapi.FastAPI()). If another middleware is configured after an application is initialized it will not be traced.
Here's an example of a fastapi middleware being configured after
fastapi.FastApi()is called: https://fastapi.tiangolo.com/tutorial/middleware/#create-a-middleware.Note - This PR only ensures Fastapi middlewares are traced. Supporting all starlette middlewares is out of scope.
Reviewer Checklist
changelog/no-changeloglabel added.