Make Django request span attributes available

[rafa-munoz]

Description

I would like to be able not to instrument certain requests within Django. E.g. when HTTP http.method=OPTIONS.

To be able to do this, I'd need to be able to access request data through attributes, which at the moment is unused:

class DjangoSampler(Sampler):
    # ...
    def should_sample(
        self,
        parent_context,
        trace_id,
        name,
        kind=None,  # noqa
        attributes=None,
        links=None,  # noqa
        trace_state=None,
    ):
        decision = Decision.RECORD_AND_SAMPLE
        if attributes and attributes.get("http.method") == "OPTIONS":
            # Do not instrument OPTIONS requests
            decision = Decision.DROP
            attributes = None
        return SamplingResult(
            decision,
            attributes,
            self._get_parent_trace_state(parent_context),
        )

    resource = Resource(
        attributes={
            "service.name": "myapp",
        }
    )
    trace.set_tracer_provider(
        TracerProvider(
            sampler=DjangoSampler(),
            resource=resource,
        )
    )

Fixes partially #936

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Using the code in the description.

Does This PR Require a Core Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

See contributing.md for styleguide, changelog guidelines, and more.

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: rafa-munoz / name: Rafael Muñoz (8c45979)

[rafa-munoz]

@srikanthccv @lzchen for any reason the build is failing in Contrib Repo Tests / build (pypy3, instrumentation, ubuntu-20.04) (pull_request) but I think it's unrelated and the error may be gone by triggering the build again. I can't restart the build. Do you have permission for that?

[rafa-munoz]

Still the same thing unfortunately:

pypy3-test-instrumentation-botocore run-test: commands[0] | pytest --benchmark-json=pypy3-instrumentation-ubuntu-20.04-benchmark.json
[863](https://github.com/open-telemetry/opentelemetry-python-contrib/actions/runs/4547788307/jobs/8018104485?pr=1730#step:6:864)
============================= test session starts ==============================
[864](https://github.com/open-telemetry/opentelemetry-python-contrib/actions/runs/4547788307/jobs/8018104485?pr=1730#step:6:865)
platform linux -- Python 3.7.13[pypy-7.3.9-final], pytest-7.2.2, pluggy-1.0.0 -- /home/runner/work/opentelemetry-python-contrib/opentelemetry-python-contrib/.tox/pypy3-test-instrumentation-botocore/bin/python
[865](https://github.com/open-telemetry/opentelemetry-python-contrib/actions/runs/4547788307/jobs/8018104485?pr=1730#step:6:866)
cachedir: .tox/pypy3-test-instrumentation-botocore/.pytest_cache
[866](https://github.com/open-telemetry/opentelemetry-python-contrib/actions/runs/4547788307/jobs/8018104485?pr=1730#step:6:867)
benchmark: 4.0.0 (defaults: timer=pytest_benchmark.timers.monotonic disable_gc=False min_rounds=5 min_time=0.000005 max_time=1.0 calibration_precision=10 warmup=True warmup_iterations=100000)
[867](https://github.com/open-telemetry/opentelemetry-python-contrib/actions/runs/4547788307/jobs/8018104485?pr=1730#step:6:868)
rootdir: /home/runner/work/opentelemetry-python-contrib/opentelemetry-python-contrib, configfile: pytest.ini
[868](https://github.com/open-telemetry/opentelemetry-python-contrib/actions/runs/4547788307/jobs/8018104485?pr=1730#step:6:869)
plugins: benchmark-4.0.0
[869](https://github.com/open-telemetry/opentelemetry-python-contrib/actions/runs/4547788307/jobs/8018104485?pr=1730#step:6:870)
collecting ... Fatal Python error: Aborted
[870](https://github.com/open-telemetry/opentelemetry-python-contrib/actions/runs/4547788307/jobs/8018104485?pr=1730#step:6:871)

[871](https://github.com/open-telemetry/opentelemetry-python-contrib/actions/runs/4547788307/jobs/8018104485?pr=1730#step:6:872)
Stack (most recent call first, approximate line numbers):
[872](https://github.com/open-telemetry/opentelemetry-python-contrib/actions/runs/4547788307/jobs/8018104485?pr=1730#step:6:873)
  File "<frozen importlib._bootstrap>", line 220 in _call_with_frames_removed
[873](https://github.com/open-telemetry/opentelemetry-python-contrib/actions/runs/4547788307/jobs/8018104485?pr=1730#step:6:874)
ERROR: InvocationError for command /home/runner/work/opentelemetry-python-contrib/opentelemetry-python-contrib/.tox/pypy3-test-instrumentation-botocore/bin/pytest --benchmark-json=pypy3-instrumentation-ubuntu-20.04-benchmark.json (exited with code -6 (SIGABRT)) (exited with code -6)

[srikanthccv]

Please rebase. It should be fixed now.