Consider otel span to be a transaction of type=message when some message attribute is set

[simitt]

TranslateTransaction only considers events that have message_bus.destination or messaging.destination set to be a transaction of type messaging. However, messaging.system is a required field according to https://opentelemetry.io/docs/specs/semconv/messaging/messaging-spans/ and should also be considered for deciding the transactions type.

See https://github.com/elastic/apm-data/blob/main/input/otlp/traces.go#L411-L414

[carsonip]

• In TranslateSpan, we are currently storing messageSystem in event.Span.Subtype and messageOperation in event.Span.Action.
• In TranslateTransaction, messaging.system and messaging.operation are currently set as labels under default in the switch statement.

Question:
We don't have subtype and action in Transaction. Should we still keep the info in a label, after using it to determine transaction type? In that case the change will look like

diff --git a/input/otlp/traces.go b/input/otlp/traces.go
index 94072c7..8b8da65 100644
--- a/input/otlp/traces.go
+++ b/input/otlp/traces.go
@@ -413,6 +413,12 @@ func TranslateTransaction(
                        case "message_bus.destination", semconv.AttributeMessagingDestination:
                                message.QueueName = stringval
                                isMessaging = true
+                       case semconv.AttributeMessagingSystem:
+                               isMessaging = true
+                               modelpb.Labels(event.Labels).Set(k, stringval)
+                       case semconv.AttributeMessagingOperation:
+                               isMessaging = true
+                               modelpb.Labels(event.Labels).Set(k, stringval)
 
                        // rpc.*
                        //

[simitt]

Yes let's keep the information set as labels. Eventually the information should be mapped to the messaging.* field, but that would be a larger undertaking as the current apm model for message differs quite a bit from otel semantic conventions for messaging, and the apm model doesn't have attributes for system and operations.

[carsonip]

Closes via #204