Akka HTTP bindFlow instrumentation broken

[ryanb93]

Description

When creating an AkkaHttp server using Http().newServerAt("localhost", 8080).bindFlow(....) instrumentation breaks. This is possibly due to handleWithAsyncHandler not being called, which is where instrumentation is hooked.

Expected Behavior

Transactions are instrumented normally.

Steps to Reproduce

Create a new server as follows:

Http().newServerAt(interface = "localhost", port).bindFlow {
  path("asyncPing") {
    get {
      complete {
        println("request made")
        StatusCodes.OK -> "Hoops!"
      }
    }
  }
}

A test has been created that shows an example of this: main...ryanb93:main

Your Environment

NewRelic Agent: 6.3.0
JVM: Java 11 OpenJDK
Akka Http: 10.2.2
Scala 2.13.3

Additional context

Some additional comments here: #149 (comment)

[tspring]

@ryanb93 Thanks for this. I'll take a look soon and see if we can't come up with a fix

[ryanb93]

Thanks

If anyone else is having the same problem, you can keep using the Routing DSL and then bind like this:

    Http()
      .newServerAt(interface, port)
      .connectionSource()
      .to(Sink.foreach(_ handleWithAsyncHandler customRoutes))
      .run()

This starts reporting transactions to the NewRelic agent however all transactions are attributed to Akka/RequestHandler and it can not distinguish between endpoints.

edit:

Additionally using bind instead of bindFlow also works:

Http().newServerAt(interface = "localhost", port).bind {
  path("asyncPing") {
    get {
      complete {
        println("request made")
        StatusCodes.OK -> "Hoops!"
      }
    }
  }
}

[ryanb93]

Some investigation:

NewRelic hooks into the following methods within akka.http.scaladsl.HttpExt

bindAndHandleAsync
bindAndHandleSync

When a server is created using bindFlow in ServerBuilder the following chain is called:

bindFlow -> bindAndHandleImpl -> bindAndHandle

When a server is created using bind the following chain is called:

bind -> bindAndHandleAsyncImpl -> bindAndHandleAsync -> bindAndHandleImpl -> bindAndHandle
                                                     -> Http2().bindAndHandleAsync //if http2 is enabled

It might be that it's better to hook into the underlying bindAndHandle function as it is called by bindAndHandleAsync, bindAndHandleSync, bind, and bindFlow.