feat(tracing): export OTLP trace metrics

[mabdinur]

Description

Wires ddtrace-py configuration into the libdatadog v41 OTLP trace-metrics exporter:

• Passes supported DD_TAGS entries to the metrics resource as datadog.tracer_tags, excluding reserved service, environment, version, and runtime ID keys.
• Adds DD_TRACE_STATS_ADDITIONAL_TAGS and forwards the selected span-tag keys to native stats aggregation.
• Exposes both settings through the PyO3 builder and Python type stubs.
• Adds writer and OTLP payload coverage plus a customer-facing feature release note.

This follows the contract introduced in system-tests#7363 and refined in system-tests#7466.

Testing

• cargo check --locked --manifest-path src/native/Cargo.toml
• scripts/lint checks
• Coverage in tests/tracer/test_writer.py and tests/opentelemetry/test_otlp_trace.py

Risks

The new export path is disabled unless OTEL_TRACES_SPAN_METRICS_ENABLED=true.

Additional Notes

Stacked on #19580, which updates libdatadog to v41.0.0 and must merge first.

[cit-pr-commenter-54b7da]

Circular import analysis

⚠️ Existing circular imports

There are 5 circular imports that already exist on the base branch and have not been changed by this PR.

ddtrace.contrib.internal.pytorch._distributed -> ddtrace.contrib.internal.pytorch._rank_root -> ddtrace.contrib.internal.pytorch._distributed
ddtrace.contrib.internal.django.patch -> ddtrace.contrib.internal.django.response -> ddtrace.contrib.internal.django.patch
ddtrace.errortracking._handled_exceptions.bytecode_injector -> ddtrace.errortracking._handled_exceptions.callbacks -> ddtrace.errortracking._handled_exceptions.collector -> ddtrace.errortracking._handled_exceptions.bytecode_reporting -> ddtrace.errortracking._handled_exceptions.bytecode_injector
ddtrace.llmobs -> ddtrace.llmobs._evaluators -> ddtrace.llmobs._evaluators.format -> ddtrace.llmobs._experiment -> ddtrace.llmobs
ddtrace.appsec._asm_request_context -> ddtrace.appsec._iast._iast_request_context_base -> ddtrace.appsec._iast._iast_env -> ddtrace.appsec._iast.reporter -> ddtrace.appsec._exploit_prevention.stack_traces -> ddtrace.appsec._asm_request_context

[cit-pr-commenter-54b7da]

Dependency direction analysis

⚠️ Existing dependency direction violations

There are 255 dependency direction violations that already exist on the base branch and have not been changed by this PR.

Show existing violations (showing 5 of 255 highest severity)

ddtrace.internal.tracemethods -×-> ddtrace.trace  (internal-core -> product:tracing, score=134)
ddtrace.llmobs._integrations.crewai -×-> ddtrace.trace  (product:llmobs -> product:tracing, score=132)
ddtrace.internal.ci_visibility.api._base -×-> ddtrace.trace  (product:ci_visibility -> product:tracing, score=132)
ddtrace.debugging._signal.tracing -×-> ddtrace.trace  (product:debugging -> product:tracing, score=132)
ddtrace.llmobs._utils -×-> ddtrace.trace  (product:llmobs -> product:tracing, score=132)

To see all violations, download the layers-base.json and layers-pr.json artifacts from this CI job and run:

uv run --script scripts/import-analysis/layers.py compare layers-base.json layers-pr.json

[cit-pr-commenter-54b7da]

Codeowners resolved as

Resolved from the full PR diff against main using the target branch CODEOWNERS file.
CODEOWNERS team requests not listed below are not required by the current file set.

ddtrace/internal/native/_native.pyi                                     @DataDog/apm-core-python
ddtrace/internal/settings/_config.py                                    @DataDog/python-guild @DataDog/apm-sdk-capabilities-python
ddtrace/internal/settings/_supported_configurations.py                  @DataDog/apm-python
ddtrace/internal/writer/writer.py                                       @DataDog/apm-core-python
releasenotes/notes/add-otlp-trace-metrics-83cad1e1cdcc65c7.yaml         @DataDog/apm-python
src/native/data_pipeline/mod.rs                                         @DataDog/apm-core-python
supported-configurations.json                                           @DataDog/apm-python
tests/integration/test_trace_stats.py                                   @DataDog/apm-core-python
tests/tracer/test_writer.py                                             @DataDog/apm-sdk-capabilities-python

[datadog-prod-us1-5]

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 65ae0d6 | Docs | Datadog PR Page | Give us feedback!}

[pr-commenter]

Benchmarks

Benchmark execution time: 2026-08-13 20:10:35

Comparing candidate commit 65ae0d6 in PR branch codex/otlp-trace-metrics-export with baseline commit 41afee5 in branch main.

Found 0 performance improvements and 8 performance regressions! Performance is the same for 609 metrics, 10 unstable metrics.

scenario:httppropagationinject-ids_only

• 🟥 execution_time [+2.843µs; +3.022µs] or [+13.645%; +14.502%]

scenario:iastaspects-capitalize_noaspect

• 🟥 execution_time [+16.259µs; +20.664µs] or [+8.662%; +11.009%]

scenario:iastaspects-index_aspect

• 🟥 execution_time [+9.484µs; +12.005µs] or [+7.700%; +9.747%]

scenario:iastaspects-stringio_aspect

• 🟥 execution_time [+649.962µs; +678.155µs] or [+17.584%; +18.347%]

scenario:iastaspectsospath-ospathbasename_aspect

• 🟥 execution_time [+94.855µs; +101.824µs] or [+23.609%; +25.344%]

scenario:span-start

• 🟥 execution_time [+1.182ms; +1.366ms] or [+7.359%; +8.503%]

scenario:telemetryaddmetric-1-count-metric-1-times

• 🟥 execution_time [+304.605ns; +349.553ns] or [+11.789%; +13.528%]

scenario:tracer-small

• 🟥 execution_time [+30.213µs; +32.864µs] or [+8.663%; +9.423%]