"failed to decode trace id" warning by DataDog for Python OpenTelemetry logs

[oldium]

When the logs do not contain trace ID and span ID, the DataDog Go mapping spams the output with failed to decode trace id and failed to decode span id.

I tracked the problem down to the otel* variables, which has default "0":

            record.otelSpanID = "0"
            record.otelTraceID = "0"
            record.otelTraceSampled = False

This is decoded like a span ID/trace ID, so the 16 and 32 characters length check of the parser fails:

opentelemetry-mapping-go/pkg/otlp/logs/transform.go

Lines 92 to 93 in 70cee9d

	case "traceid", "trace_id", "contextmap.traceid", "oteltraceid":
	traceID, err := decodeTraceID(v.AsString())

opentelemetry-mapping-go/pkg/otlp/logs/transform.go

Lines 104 to 105 in 70cee9d

	case "spanid", "span_id", "contextmap.spanid", "otelspanid":
	spanID, err := decodeSpanID(v.AsString())

And the decoding:

opentelemetry-mapping-go/pkg/otlp/logs/transform.go

Lines 226 to 236 in 70cee9d

	func decodeTraceID(traceIDStr string) (pcommon.TraceID, error) {
	var id pcommon.TraceID
	if hex.DecodedLen(len(traceIDStr)) != len(id) {
	return pcommon.TraceID{}, errors.New("trace ids must be 32 hex characters")
	}
	_, err := hex.Decode(id[:], []byte(traceIDStr))
	if err != nil {
	return pcommon.TraceID{}, err
	}
	return id, nil
	}

opentelemetry-mapping-go/pkg/otlp/logs/transform.go

Lines 238 to 248 in 70cee9d

	func decodeSpanID(spanIDStr string) (pcommon.SpanID, error) {
	var id pcommon.SpanID
	if hex.DecodedLen(len(spanIDStr)) != len(id) {
	return pcommon.SpanID{}, errors.New("span ids must be 16 hex characters")
	}
	_, err := hex.Decode(id[:], []byte(spanIDStr))
	if err != nil {
	return pcommon.SpanID{}, err
	}
	return id, nil
	}

[oldium]

The full log line is the following:

2025-03-07T22:58:41.395Z	warn	[email protected]/transform.go:107	failed to decode span id	{"otelcol.component.id": "datadog", "otelcol.component.kind": "Exporter", "otelcol.signal": "logs", "span_id": "0", "error": "span ids must be 16 hex characters"}
2025-03-07T22:58:41.395Z	warn	[email protected]/transform.go:95	failed to decode trace id	{"otelcol.component.id": "datadog", "otelcol.component.kind": "Exporter", "otelcol.signal": "logs", "trace_id": "0", "error": "trace ids must be 32 hex characters"}