start_child_span config creates spans with the wrong span.kind

[MisterSquishy]

Title: start_child_span config creates spans with the wrong span.kind

Description: when the start_child_span config is set to true, i would expect envoy to emit router .* egress spans with the span.kind set to client. instead, it copies the parent config, which has span.kind set to server

Repro steps: set the start_child_span config to true and inspect the emitted spans

[adisuissa]

Seems to be a question related to tracing. This feature has been there for a while (since #1931). cc @mattklein123 @wbpcode as tracing domain experts.

[wbpcode]

Hi, which tracer are you using? Different tracers may have different behaviors.

[MisterSquishy]

we are using the opentelemetry tracer!

[wbpcode]

got it. I think this is a similar problem with previous zipkin. #22987

The tracer could work on two mode:

• work as sidecar of app, the inound sidecar will output server spans and outbound sidecar will output client spans. Both inbount sidecar and outbound composite an independent hop.
• work as independent hop, output server spans for downstream and output client spans for upstream.

Because historical reason, value of Tracing::OperationName is mainly depend on the traffic direction and could use it to determine the type of span.

Seems we need a more complete solution to this problem. cc @mattklein123

[github-actions[bot]]

This issue has been automatically marked as stale because it has not had activity in the last 30 days. It will be closed in the next 7 days unless it is tagged "help wanted" or "no stalebot" or other activity occurs. Thank you for your contributions.

[github-actions[bot]]

This issue has been automatically closed because it has not had activity in the last 37 days. If this issue is still valid, please ping a maintainer and ask them to label it as "help wanted" or "no stalebot". Thank you for your contributions.