Allow custom trace attribute keys

[loicsaintroch]

Is your feature request related to a problem? Please describe. Trace attribute keys are enforced by the Temporal SDK, and are as follow:

• temporalWorkflowID
• temporalRunID
• temporalActivityID

Found here: https://github.com/temporalio/sdk-go/blob/master/interceptor/tracing_interceptor.go#L39-L43

The only way to customise those keys is to create our own implementation of interceptor.Interceptor which is kind of heavy work to simply rename these keys.

Describe the solution you'd like We could have the possibility to override the key values set by default in interceptor.TracerOptions, and port these options to opentelemetry.TracerOptions and opentracing.TracerOptions.

Additional context Issue related to this thread on Slack

[loicsaintroch]

As discussed on Slack, here's a possible approach without having a custom interceptor.Interceptor.

Create your own interceptor.Tracer, and override the StartSpan function:

type MyCustomTracer struct {
	interceptor.Tracer
}

func (m MyCustomTracer) StartSpan(opts *interceptor.TracerStartSpanOptions) (interceptor.TracerSpan, error) {
	if v := opts.Tags["temporalWorkflowID"]; v != "" {
		opts.Tags["temporal.workflow.id"] = v
		delete(opts.Tags, "temporalWorkflowID")
	}

	if v := opts.Tags["temporalRunID"]; v != "" {
		opts.Tags["temporal.workflow.run_id"] = v
		delete(opts.Tags, "temporalRunID")
	}

	if v := opts.Tags["temporalActivityID"]; v != "" {
		opts.Tags["temporal.activity.id"] = v
		delete(opts.Tags, "temporalActivityID")
	}

	return m.Tracer.StartSpan(opts)
}

Create a new tracer using the distribution of your choice, such as opentelemetry. Then pass this tracer in interceptor.NewTracingInterceptor:

otelTracer, err := opentelemetry.NewTracer(opentelemetry.TracerOptions{
	// ...
})

customTracer := MyCustomTracer{
	Tracer: otelTracer,
}

var opts = client.Options{
	Interceptors: []interceptor.ClientInterceptor{
		interceptor.NewTracingInterceptor(customTracer),
	},
}

Leaving this issue open to let the Temporal decide if/how this should be documented or if another approach should be implemented.

[throwaway58383958484]

+1 for this. We would like to inject additional attributes on our traces, and there doesn't seem to be a good way to do it. Even if we override StartSpan as described in this comment (great idea, by the way), we'd like to include tags that we're storing on our context, but unfortunately the context is unavailable there.