tracing: Set span.kind tag for opencensus tracer when creating client/server spans

[verysonglaa]

Currently OpenTracing tracers and the zipkin tracer derives the span.kind (or cs/cr/ss/sr annotations) from the tracing config "operation_name" - however opencensus tracer doesn't have this tag set.

The proxy needs to explicitly set this tag when creating the span. This is similiar to #3435 which was resolved in 42a9cae (but this time just for opencensus)

[dio]

cc. @objectiser

[objectiser]

Sorry for delay in looking at this - having trouble with build environment since upgrading to Fedora 32 due to docker issues 😞

[objectiser]

Need to get clarification on how OpenCensus should handle span kind before deciding on next step - potentially having to do changes in OC C++ client first.

[objectiser]

Unfortunately this will require support for span kind to be added to the OC C++ lib and its supported exporters. Currently don't have time to work on that, so if anyone else wants to take it.

[github-actions]

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.

[verysonglaa]

/remove stale

[F21]

I am also looking at using istio with opentelemetry. Since Opencensus is pretty much deprecated at this point in favor of Opentelemetry, would it make sense to focus our efforts on Opentelemetry instead?

I noticed there's an open issue to directly embed the opentelemetry collector into istio: istio/istio#30503 , however there are still a fair bit of design decisions to make. In the short term would it be more achievable to add support for exporting metrics and traces in oltp format to an opentelemetry collector that is not managed by istio?

[moderation]

@F21 related open issue at #9958

[verysonglaa]

If we get opentelemetry support directly in envoy/istio I guess this would be even better. Unfortunately I don't see much progress there.

[m-mijatovic]

I would also be interested in direct support of open telemetry in Istio and most definitely do not require that the collector be managed by Istio. Is the only solution for now to use OpenCensus Tracer and configure W3C trace context to avoid propagating the headers manually?

[verysonglaa]

@m-mijatovic I can see only this solution at the moment. So we have this OpenCensus Tracer with W3C trace running until open telemetry is directly supported.