Question

A payments microservice running on GKE calls three downstream services. You have enabled OpenTelemetry auto-instrumentation and export traces to Cloud Trace. When you inspect a trace in the Trace explorer, the root span for the payments service appears, but the spans for one downstream service (a legacy internal billing API) are consistently missing, even though logs confirm the billing API is being called and responding. What is the MOST likely reason the billing API spans are absent from the trace waterfall?

Accepted Answer

The billing API is not propagating or generating trace context, so its spans are not associated with the parent trace ID.

Answer

Cloud Trace sampling rate is set too low, so only the root span is captured for every request.

Answer

The payments service is exporting traces to the wrong Google Cloud project's Trace backend.

Answer

Cloud Trace automatically drops spans from services that respond in under 100 ms.