feat(traces): add OTLP http/json trace export#251
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Route Datadog trace chunks through libdd-data-pipeline's TraceExporter OTLP http/json path when OTEL_TRACES_EXPORTER=otlp, mirroring the existing metrics and logs OTLP integration in the datadog-opentelemetry crate. Configuration: - OTEL_TRACES_EXPORTER (otlp enables OTLP export; none disables tracing) - OTEL_EXPORTER_OTLP_TRACES_ENDPOINT, with fallback to OTEL_EXPORTER_OTLP_ENDPOINT (strip trailing slash, append /v1/traces) and a computed default http://<agent_host>:4318/v1/traces (host derived from the resolved trace-agent URL, matching the metrics/logs helpers) - OTEL_EXPORTER_OTLP_TRACES_HEADERS (fallback OTEL_EXPORTER_OTLP_HEADERS; sensitive, excluded from config telemetry) - OTEL_EXPORTER_OTLP_TRACES_TIMEOUT (fallback OTEL_EXPORTER_OTLP_TIMEOUT) - OTEL_EXPORTER_OTLP_TRACES_PROTOCOL (parsed and reported; only http/json is honored this phase, a warning is logged otherwise) - OTEL_TRACES_SAMPLER / OTEL_TRACES_SAMPLER_ARG mapped to a Datadog sample rate - DD_TRACE_AGENT_PROTOCOL_VERSION disables OTLP export when set The agent URL stays separate from the OTLP endpoint so /info, Remote Config, and telemetry keep talking to the Datadog agent. libdatadog drops unsampled (priority < 1) chunks before OTLP send, so only sampled spans are exported. Adds config-resolution unit tests (endpoint fallback, header parsing, timeout resolution, gates, sampler mapping/validation) and an in-repo integration test that emits a span with no external OpenTelemetry SDK setup and asserts the OTLP http/json payload reaches a local HTTP endpoint, plus that dropped spans are not exported. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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This was referenced Jun 10, 2026
bm1549
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validate_supported_configurations_v2 failed: the new config entries used placeholder version 'A' / default null. Match the registry: DD_TRACE_AGENT_PROTOCOL_VERSION default 0.4 (A); OTEL_EXPORTER_OTLP_TRACES_PROTOCOL B; OTEL_TRACES_EXPORTER C (string exporter selector); OTEL_TRACES_SAMPLER E. Doc-only — the generated config map and runtime defaults are unchanged. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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What does this PR do?
Adds OTLP trace export to dd-trace-rs. When
OTEL_TRACES_EXPORTER=otlpis set, finished trace chunks are exported over OTLP http/json to an OpenTelemetry collector instead of the Datadog agent's MessagePack endpoint, by wiring libdatadog'sTraceExporterOTLP path (set_otlp_endpoint/set_otlp_headers/set_connection_timeout). This mirrors the existing metrics/logs OTLP wiring.Configuration (parsed and reported via config telemetry; headers excluded as sensitive):
OTEL_TRACES_EXPORTER—otlpenables OTLP export;nonedisables tracingOTEL_EXPORTER_OTLP_TRACES_ENDPOINT→ fallbackOTEL_EXPORTER_OTLP_ENDPOINT+/v1/traces→ defaulthttp://<agent_host>:4318/v1/tracesOTEL_EXPORTER_OTLP_TRACES_HEADERS/_TIMEOUT(10s) /_PROTOCOL(onlyhttp/jsonhonored this phase; warns otherwise)OTEL_TRACES_SAMPLER/_ARGmapped to a sample rate with a parentbased fallbackBehavior:
DD_TRACE_AGENT_PROTOCOL_VERSIONdisables OTLP;DD_TRACE_SAMPLE_RATE/DD_TRACE_SAMPLING_RULEStake precedence over the OTel sampler; only sampled spans are exported (libdatadogdrop_chunks); the agent URL is kept separate so/info, Remote Config, and telemetry keep talking to the agent.Motivation
Part of the cross-language OTLP Traces Export effort (RFC "OTLP Traces Export 2026Q1", Phase 1): let the Datadog SDK emit traces over OTLP for users running an OpenTelemetry collector. Rust uses the same libdatadog exporter as dd-trace-py.
Additional Notes
~22 unit + integration tests (config resolution, gates, sampler mapping, real http/json POST to
/v1/traces, unsampled-drop);cargo fmtandcargo clippyclean across all feature combinations. Scope is RFC Phase 1: http/json only — no gRPC, no W3C TraceContext L2 / TraceState probability sampling, no trace stats, no OTel semantic conventions.Related PRs (cross-language OTLP traces export — system-tests validates all three tracers):
Merge order: libdatadog #2101 → dd-trace-php #3971 (re-bump the submodule to the released libdatadog commit). system-tests #7121 validates rust/ruby/php once the tracer branches are available.
🤖 Generated with Claude Code