awsxrayexporter: Logic for how Service Name is set for "root" spans

[Alinoe22]

In our applications we have a mixture of spans and we use all types (Server, Client, Consumer, Producer, Internal).

In particular, some of our spans are INTERNAL because they are triggered internally and not by a RPC or broadcast call.

So I can have an INTERNAL span called "Initialisation" for instance where the service name is set as "My Application".
If look at the trace in Tempo/Grafana, the trace appears (as expected) as belonging to the service "My Application".
But if I look at the same trace in AWS CloudWatch, the name of the node is not "My Application" but "Initialisation" instead.

I believe this behaviour is because of this code:

	if span.Kind() == ptrace.SpanKindServer {
		if localServiceName, ok := attributes.Get(awsLocalService); ok {
			name = localServiceName.Str()
		}
	}

	myAwsSpanKind, _ := span.Attributes().Get(awsSpanKind)
	if span.Kind() == ptrace.SpanKindInternal && myAwsSpanKind.Str() == localRoot {
		if localServiceName, ok := attributes.Get(awsLocalService); ok {
			name = localServiceName.Str()
		}
	}

So currently in order to work around this logic, we are setting the type of our root internal traces as SERVER so that the node appears correctly.
The same outcome would work if we set a property aws.span.kind to LOCAL_ROOT but while this would work, it sounds weird to set AWS specific attributes so that the exporter behaves correctly.

To me the following logic would make more sense but I wanted to ask this here as I don't fully understand the rationale with the current code:

	if span.Kind() == ptrace.SpanKindServer ||
            span.ParentSpanID().IsEmpty() {
		if localServiceName, ok := attributes.Get(awsLocalService); ok {
			name = localServiceName.Str()
		}
	}

If a trace does not have a parent, it is root by definition and therefore the name should behave the same as a Server ?

This logic is similar to the earlier code where a span is considers a subsegment if:

• it is not SERVER
• and it is not CONSUMER
• and it does not have a parent

By correlation, a span is a top segment if it does not have a parent?

Thanks