[thomasqueirozb]

Summary

Stacked on #26590. The otlp codec now converts native trace events from the opentelemetry source (decoded without use_otlp_decoding) to OTLP spans, through legacy_to_typed and ExportTraceServiceRequest::from_events. Events that already have resourceSpans are still encoded as before. Datadog traces, and traces where every span is rejected, fail as encode errors.

Conversion issues are reported through a new rate-limited warning event (OtlpTraceConversionIssue). It does not count as an error or a drop because the event is still delivered. Feedback on this reporting choice is welcome.

References

• Related: chore(opentelemetry): map OTLP traces onto the RFC 25329 typed event #26590
• Related: feat(codecs): convert native Vector logs to OTLP in otlp serializer #26605
• Related: chore(traces): Add RFC for typed internal trace data model #25329

Vector configuration

sources:
  otel_in:
    type: opentelemetry
    grpc:
      address: 0.0.0.0:43170
    http:
      address: 0.0.0.0:43180

sinks:
  to_collector:
    type: opentelemetry
    inputs: [otel_in.traces]
    protocol:
      type: http
      uri: http://127.0.0.1:44318/v1/traces
      encoding:
        codec: otlp

How did you test this PR?

• Unit tests: flattened trace converted to OTLP; trace with only rejected spans is an error; Datadog trace is an error.
• Sent 2 traces (4 spans) with telemetrygen to the config above, which forwarded them to an OpenTelemetry Collector 0.111.0 (debug exporter). All spans arrived with trace, span, and parent IDs, kind, timestamps, and attributes. No conversion warnings were logged.

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the no-changelog label to this PR.

[bruceg]

Found some must-fix issues below