java.lang.NoClassDefFoundError: akka/http/scaladsl/server/Directive$SingleValueTransformers$

[kjorg50]

Hi, I'm trying to use Kamon for the first time with a Scala akka-http application. All I have done so far is follow the Getting Started page to add the kamon-bundle package to my gradle file, and then add the Kamon.init() line to the main function for my app. When I start it up I see the Kanela agent log message but shortly thereafter I get this stack trace

Exception in thread "main" java.lang.NoClassDefFoundError: akka/http/scaladsl/server/Directive$SingleValueTransformers$
	at kamon.instrumentation.akka.http.PathDirectivesRawPathPrefixInterceptor$.rawPathPrefix(AkkaHttpServerInstrumentation.scala:269)
	at kamon.instrumentation.akka.http.PathDirectivesRawPathPrefixInterceptor.rawPathPrefix(AkkaHttpServerInstrumentation.scala)
	at akka.http.scaladsl.server.directives.PathDirectives.rawPathPrefix(PathDirectives.scala)
	at akka.http.scaladsl.server.directives.PathDirectives.rawPathPrefix$(PathDirectives.scala:51)
	at akka.http.scaladsl.server.Directives$.rawPathPrefix(Directives.scala:41)
	at akka.http.scaladsl.server.directives.PathDirectives.pathPrefix(PathDirectives.scala:41)
	at akka.http.scaladsl.server.directives.PathDirectives.pathPrefix$(PathDirectives.scala:41)
	at akka.http.scaladsl.server.Directives$.pathPrefix(Directives.scala:41)
	at akka.http.scaladsl.server.directives.PathDirectives.path(PathDirectives.scala:32)
	at akka.http.scaladsl.server.directives.PathDirectives.path$(PathDirectives.scala:32)
	at akka.http.scaladsl.server.Directives$.path(Directives.scala:41)
	at example.robot.health.LifecycleMonitorImpl.<init>(LifecycleMonitorImpl.scala:153)
	at example.robot.RobotApp$.main(RobotApp.scala:38)
	at example.robot.RobotApp.main(RobotApp.scala)
Caused by: java.lang.ClassNotFoundException: akka.http.scaladsl.server.Directive$SingleValueTransformers$
	at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:349)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
	... 14 more

Here are some of the versions I am using:

• org.scala-lang:scala-library:2.12.11
• com.typesafe.akka:akka-http_2.12:10.1.1
• com.typesafe.akka:akka-actor_2.12:2.5.12
• io.kamon:kamon-bundle_2.12:2.1.4

FWIW, I added these configs to my application.conf but I don't think they make a difference right now

kamon.instrumentation.akka.http {
  server {
    metrics {
      enabled = yes
    }
    propagation {
      enabled = yes
      channel = default
    }
    tracing {
      enabled = yes
      span-metrics = on
    }
  }
  client {
    propagation {
      enabled = yes
      channel = default
    }
    tracing {
      enabled = yes
      span-metrics = on
    }
  }
}

The most similar issue I could find was this, but the fix to that is unclear to me. Can anyone provide some insight to this issue? Thanks!

[kjorg50]

Found that the SingleValueTransformers class was added in akka-http 10.1.8 so my version of akka-http was too old 🤦

I updated to the following versions and now I am able to run my app!

akka = 2.5.19
akkaHttp = 10.1.8

[SimunKaracic]

Good find!