scala-akka's Introduction

OpenTracing Scala Akka instrumentation

OpenTracing instrumentation for Scala Akka.

Installation

build.sbt

libraryDependencies += "io.opentracing.contrib" % "opentracing-scala-akka" % "VERSION"

Usage

Tracer registration

Instantiate tracer and register it with GlobalTracer:

val tracer: Tracer = ???
GlobalTracer.register(tracer)

Actor's Span propagation

User is responsible for finishing the Spans. For this to work, classes must inherit from TracedAbstractActor instead of Actor, and messages must be wrapped using TracedMessage.wrap():

class MyActor extends TracedAbstractActor {
  override def receive(): Receive = {
    case _: String =>
      sender().tell("ciao", self)
  }
}

val scope =  tracer.buildSpan("foo").startActive(true)

// scope.span() will be captured as part of TracedMessage.wrap(),
// and MyActor will receive the original 'myMessageObj` instance.
val future = ask(myActorRef, TracedMessage.wrap("hello"), timeout)
...
    
scope.close()
    
}

By default, TracedAbstractActor/TracedMessage use io.opentracing.util.GlobalTracer to activate and fetch the Span respectively, but it's possible to manually specify both the Tracer used to activate and the captured Span:

class MyActor(myTracer: Tracer) extends TracedAbstractActor {
  override def receive(): Receive = {
    case _: String =>
      // TracedAbstractActor.tracer() returns the Tracer being used,
      // either GlobalTracer 
      if (tracer().activeSpan() != null) {
        // Use the active Span, to set tags, create children, finish it, etc.
        tracer().activeSpan.finish()
      }
      ...
  }

  override def tracer(): Tracer = myTracer
}

val span = tracer.buildSpan("foo").start()
val future = ask(myActorRef, TracedMessage.wrap(span, "hello"), timeout);