How to configure Kamon for dockerized Akka application?

Question

I created a sample service in Akka for testing Kamon + DataDog monitoring.

Here are dependencies which I added:

"io.kamon" %% "kamon-core" % "1.1.0",
"io.kamon" %% "kamon-datadog" % "1.0.0",
"io.kamon" %% "kamon-akka-2.5" % "1.0.1"

Here are plugins enabled in build.sbt:

.enablePlugins(AshScriptPlugin, DockerPlugin, SbtAspectJRunner)

Then application.conf:

kamon {
  datadog {
    time-units = "ms"
    memory-units = "b"
  }
  util {
    filters {
      "akka.tracked-actor" {
        includes = [ "testSystem/user/**" ]
        excludes = [ "testSystem/system/**" ]
      }

      "s3-worker-actors" {
        includes = [ "testSystem/user/s3Router/*" ]
      }

      "fb-worker-actors" {
        includes = [ "testSystem/user/fbRouter/*" ]
      }

      "akka.tracked-router" {
        includes = [ "testSystem/user/s3Router", "testSystem/user/fbRouter" ]
      }

      "akka.tracked-dispatcher" {
        includes = [ "**" ]
      }

      "akka.traced-actor" {
        includes = [ "**" ]
      }
    }
  }
  akka.actor-groups = [ "s3-worker-actors", "fb-worker-actors" ]
}

Finally in the Main class I invoke:

Kamon.addReporter(new DatadogAgentReporter())

On EC2 I installed datadog-agent for docker.

When I run the service container on the EC2 instance and then look into the DataDog interface I don't see any related metrics to akka, just a list of standard metrics like: datadog.process.agent, docker.cpu.usage, system.io.await etc

How to enable akka related metrics in case when an akka app is packaged into docker and deployed on EC2?

Answer 1

It is necessary to add AspectJ weaver as Java Agent when you're starting your Akka aplication: -javaagent:aspectjweaver.jar

You can add the following settings in your project SBT configuration:

.settings(
  retrieveManaged := true,
  libraryDependencies += "org.aspectj" % "aspectjweaver" % aspectJWeaverV)

So AspectJ weaver JAR will be copied to ./lib_managed/jars/org.aspectj/aspectjweaver/aspectjweaver-[aspectJWeaverV].jar in your project root.

Then you can refer this JAR in your Dockerfile:

COPY ./lib_managed/jars/org.aspectj/aspectjweaver/aspectjweaver-*.jar /app- 
workdir/aspectjweaver.jar
WORKDIR /app-workdir
CMD ["java", "-javaagent:aspectjweaver.jar", "-jar", "app.jar"]