Support Akka/Pekko Cluster

[zackman0010]

Is your feature request related to a problem? Please describe.

Akka (and its fork Pekko) has the concept of Cluster, or communication between multiple nodes of the same service. OTel is already capable of message propagation through Akka Actors, but the propagation is broken if the message passes to a different node through Akka Remoting, which is what Cluster uses under-the-hood.

Describe the solution you'd like

I'd like to see auto-instrumentation support Akka Remoting.

Describe alternatives you've considered

No response

Additional context

Akka Remoting got a big overhaul starting in Akka 2.6, so 2.5 and lower would either need a separate instrumentation or not be instrumented. As Pekko was forked off 2.6, the Akka 2.6 instrumentation can be copied for Pekko, just renaming the classes.

Also, Kamon's auto-instrumentation agent already supports Akka Remoting, both 2.5 and 2.6. Their code is also open source under the Apache license, so it might be a good starting point to see how they instrumented Remoting to use it as an inspiration for how to instrument it in OTel.

[laurit]

We'd welcome a contribution for this

[pjfanning]

The Kamon support involves overriding the Akka/Pekko code that writes and later reads the messages sent between the cluster members. Protobuf is used and the Kamon message is a modified version of the original message that tacks on Kamon Context information. Kamon uses bytebuddy in a very similar way to OpenTelemetry. The main code for kamon-pekko is:

• https://github.com/kamon-io/Kamon/blob/master/instrumentation/kamon-pekko/src/main/java/pekko/remote/ContextAwareWireFormats_Pekko.java
• https://github.com/kamon-io/Kamon/blob/master/instrumentation/kamon-pekko/src/main/scala/kamon/instrumentation/pekko/remote/internal/PekkoPduProtobufCodecDecodeMessageMethodAdvisor.scala
• https://github.com/kamon-io/Kamon/blob/master/instrumentation/kamon-pekko/src/main/scala/kamon/instrumentation/pekko/remote/internal/PekkoPduProtobufCodecConstructMessageMethodInterceptor.scala

[github-actions]

Since there has been no activity on this enhancement for the past year we are closing it to help maintain our backlog. Anyone who would like to work on it is still welcome to do so, and we can re-open it at that time.