[Feature] [Tracing] Add OTLP Tracing support as a Zipkin trace input

[wu-sheng]

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• I had searched in the issues and found no similar feature requirement.

Description

We are declaring to support OTLP trace format through OTLP collector and forward to Zipkin receiver.

This works, but an extra component seems unnecessary.

OTLP trace format is logically the same as the Zipkin trace format, so, we just need to add a OLTP trace handler and an in-memory converter to Zipkin receiver.

Use case

receiver-otel:
  selector: ${SW_OTEL_RECEIVER:default}
  default:
    enabledHandlers: ${SW_OTEL_RECEIVER_ENABLED_HANDLERS:"otlp-metrics,otlp-logs"}
    enabledOtelMetricsRules: ....

We should add otlp-trace as an option to enabledHandlers to support this.

@kezhenxu94 Any suggestion?

Related issues

No response

Are you willing to submit a pull request to implement this on your own?

• Yes I am willing to submit a pull request on my own!

Code of Conduct

• I agree to follow this project's Code of Conduct

[wu-sheng]

To be clear, this would not forward any OAL sources like the previous Zipkin receiver.

[kezhenxu94]

Not sure what you want, OpenTelemetry agents can send traces directly to Zipkin server

https://github.com/open-telemetry/opentelemetry-java/blob/3b1c6d9108f7e25afe5d0fdae830458e8c1a481b/sdk-extensions/autoconfigure/README.md#zipkin-exporter

[wu-sheng]

Some agents could, I am thinking wider support only.

[kezhenxu94]

It sounds kind of out of skywalking’s scope to convert one third party format (OpenTelemetry) to another third party format (Zipkin)