feature(tracing): add support for inferred proxy spans to support AWS API Gateway tracing

[wconti27]

Motivation

Adds support for inferred proxy spans created from distributed headers for web server integrations.

Checklist

• PR author has checked that all the criteria below are met
• The PR description includes an overview of the change
• The PR description articulates the motivation for the change
• The change includes tests OR the PR description describes a testing strategy
• The PR description notes risks associated with the change, if any
• Newly-added code is easy to change
• The change follows the library release note guidelines
• The change includes or references documentation updates if necessary
• Backport labels are set (if applicable)

Reviewer Checklist

• Reviewer has checked that all the criteria below are met
• Title is accurate
• All changes are related to the pull request's stated goal
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Newly-added code is easy to change
• Release note makes sense to a user of the library
• If necessary, author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[github-actions]

CODEOWNERS have been resolved as:

ddtrace/_trace/_inferred_proxy.py                                       @DataDog/apm-sdk-api-python
tests/tracer/utils_inferred_spans/__init__.py                           @DataDog/apm-sdk-api-python
tests/tracer/utils_inferred_spans/test_helpers.py                       @DataDog/apm-sdk-api-python
ddtrace/_trace/trace_handlers.py                                        @DataDog/apm-sdk-api-python
ddtrace/ext/__init__.py                                                 @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/settings/config.py                                              @DataDog/python-guild @DataDog/apm-sdk-api-python
tests/contrib/aiohttp/test_middleware.py                                @DataDog/apm-core-python @DataDog/apm-idm-python
tests/contrib/django/test_django.py                                     @DataDog/apm-core-python @DataDog/apm-idm-python
tests/contrib/flask/test_request.py                                     @DataDog/apm-core-python @DataDog/apm-idm-python
tests/utils.py                                                          @DataDog/python-guild

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: conti/support-aws-api-gateway
Commit report: d3eea29
Test service: dd-trace-py

✅ 0 Failed, 130 Passed, 1468 Skipped, 4m 34.05s Total duration (36m 10.42s time saved)

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-01-25 00:35:26

Comparing candidate commit 85bcab2 in PR branch conti/support-aws-api-gateway with baseline commit ee226aa in branch conti/standardize-web-frameworks-to-use-core.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 394 metrics, 2 unstable metrics.

[wantsui]

Just adding a note to fix/investigate this: Even if the above line was fixed: span_kwargs = ctx.get_item("span_kwargs"), when it hits this line, it throws an error about tracer.trace not accepting a child of argument:

TypeError: Tracer.trace() got an unexpected keyword argument 'child_of'

In https://github.com/DataDog/dd-trace-py/pull/11938/files, it used start_span which supports it.

[wconti27]

this should be fixed, there has to be a check to ensure trace() is not being called since it auto-handles context.