Parent-id logic improvement

[Zusel]

Hey,
I have two feature requests:

• The ability to set a parent ID within a running transaction. This is needed, for example, when the parent ID is determined during a process and is not yet known at the start.

• Currently, a transactionWithRemoteParent can only be started if you have an ID. However, there are cases where this ID is unknown. Therefore, it would be advantageous to be able to pass multiple key-pair filters. Based on these, the APM server could then find the appropriate parent ID. I consider a lookup via an Elasticsearch client or similar to be an absolute bottleneck.

Perhaps you have better suggestions.
Thank you very much.

[JonasKunz]

Unfortunately this is not really possible due to the general tracing concept:
Imagine if in the trace containing your transaction there is an outgoing HTTP-span before you know the parent of the transaction (and therefore the trace-ID). The HTTP span needs to propagate the trace-id, which in case it is set later simply doesn't work.

The general workaround for problems like yours is to use span-links instead. Unfortunately those are currently unsupported via the Elastic APM public API and you can only add them on span start via the OpenTelemetry API in the Elastic APM agent. Adding them after the span/transaction was started is currently not implemented.

However, if possible for you, you could use EDOT instead: That agent supports adding span-links via the OpenTelemetry API method I linked.

[Zusel]

Thank you for the fast reply. I dont know the EDOT-Client but can we use this client with the Kibana-Stack? If this is the case i would try it the EDOT-Client

[JonasKunz]

Yes, it is an distribution of the OpenTelemetry java agent maintained by elastic and therefore designed to work with elasticsearch / Kibana.

I'll close this issue then, feel free to reopen if needed.

[Zusel]

Thank you :)