feat(otlp): support http/protobuf OTLP trace export

[bm1549]

Description

Adds http/protobuf as a second OTLP trace-export encoding alongside the existing http/json path. The encoding is selected from the OTel-standard OTEL_EXPORTER_OTLP_TRACES_PROTOCOL value and passed to libdatadog via the new set_otlp_protocol builder setter.

• http/json (default) and http/protobuf are supported over HTTP.
• Any other value (including the OTel grpc default, which libdatadog can't speak) falls back to http/json, preserving pre-wiring behavior.

This PR also bumps libdatadog from v35.0.0 to the OTLP branch (664f16fb, DataDog/libdatadog#2115), which the binding depends on. That bump pulls in the datadog-remote-config → libdd-remote-config rename and the redesigned remote-config parsing API, so tracer_flare.rs is ported to parse per-product via RemoteConfigContent (AgentConfigFile/AgentTaskFile).

Depends on DataDog/libdatadog#2115. The rev is pinned to that PR's branch head; bump it to the squash-merge SHA (or the next libdatadog release that includes it) before merging.

Testing

• cargo check --all-features passes with 0 warnings against the bumped libdatadog rev.
• Backend verification (local DD Agent → datadoghq.com): emitted protobuf-only OTLP traces from a fresh service and confirmed ingestion — application/x-protobuf on the wire (HTTP 200), spans landed with correct service/resource names and a preserved 128-bit trace id. http/json regression also confirmed (application/json wire, HTTP 200).
• system-tests APM_TRACING_OTLP protobuf coverage: DataDog/system-tests companion PR.

Risks

• Behavioral change is gated on _otlp_endpoint being set; non-OTLP export is unaffected.
• The libdatadog v35→main bump is the larger surface: it touches the renamed crate and the remote-config parse API used by tracer flare. cargo check --all-features is green; full CI build/test should be watched once the rev is repointed at the merged libdatadog SHA.

Additional Notes

Commits are split: (1) the libdatadog bump + tracer_flare port, (2) the OTLP protobuf feature.

[datadog-official]

 

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⚠️ Warnings

🚦 10 Pipeline jobs failed

DataDog/apm-reliability/dd-trace-py | build linux serverless: [amd64, cp315-cp315, v113741238-d2b8243-manylinux2014_x86_64, 1]     

DataDog/apm-reliability/dd-trace-py | build linux serverless: [amd64, cp315-cp315, v113741491-d2b8243-musllinux_1_2_x86_64, 1]     

DataDog/apm-reliability/dd-trace-py | build linux serverless: [arm64, cp315-cp315, v113741357-d2b8243-manylinux2014_aarch64, 1]     

View all 10 failed jobs.

ℹ️ Info

No other issues found (see more)

🧪 All tests passed
❄️ No new flaky tests detected

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[cit-pr-commenter-54b7da]

Codeowners resolved as

ddtrace/internal/settings/_opentelemetry.py                             @DataDog/apm-sdk-capabilities-python
ddtrace/internal/writer/writer.py                                       @DataDog/apm-core-python
src/native/data_pipeline/mod.rs                                         @DataDog/apm-core-python

[bm1549]

This is to fix a breaking change in libdatadog

[pr-commenter]

Benchmarks

Benchmark execution time: 2026-06-12 21:46:47

Comparing candidate commit ecefde5 in PR branch brian.marks/otlp-http-protobuf-export with baseline commit 33e2657 in branch main.

Found 0 performance improvements and 7 performance regressions! Performance is the same for 609 metrics, 10 unstable metrics.

scenario:iast_aspects-re_match_noaspect

• 🟥 execution_time [+24.013µs; +30.194µs] or [+7.246%; +9.111%]

scenario:iastaspects-capitalize_noaspect

• 🟥 execution_time [+22.860µs; +29.816µs] or [+8.776%; +11.447%]

scenario:iastaspects-title_aspect

• 🟥 execution_time [+45.130µs; +51.630µs] or [+13.431%; +15.365%]

scenario:iastaspectsospath-ospathbasename_aspect

• 🟥 execution_time [+89.616µs; +99.346µs] or [+20.387%; +22.600%]

scenario:iastaspectssplit-rsplit_aspect

• 🟥 execution_time [+11.887µs; +17.783µs] or [+7.755%; +11.602%]

scenario:span-start

• 🟥 execution_time [+1.297ms; +1.487ms] or [+8.322%; +9.539%]

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

• 🟥 execution_time [+204.361ns; +235.792ns] or [+9.848%; +11.362%]