Automatically starting the Kamon system metrics module on Play Applications

application.conf

play.modules.enabled += "modules.SystemMetricsModule"

SystemMetricsModule.scala

// Goes into app/modules/SystemMetricsModule.scala
package modules

import javax.inject.{Inject, Singleton}
import kamon.system.SystemMetrics
import play.api.{Configuration, Environment, Logger}
import play.api.inject.{ApplicationLifecycle, Binding, Module}
import scala.concurrent.Future

class SystemMetricsModule extends Module {
  def bindings(environment: Environment, configuration: Configuration): Seq[Binding[SystemMetricsModule.KamonSystemMetricsLoader]] = {
    Seq(bind[SystemMetricsModule.KamonSystemMetricsLoader].toSelf.eagerly())
  }
}

object SystemMetricsModule {

  @Singleton
  class KamonSystemMetricsLoader @Inject() (lifecycle: ApplicationLifecycle, environment: Environment, configuration: Configuration) {
    Logger(classOf[KamonSystemMetricsLoader]).info("Starting the Kamon System Metrics Module")
    SystemMetrics.startCollecting()

    lifecycle.addStopHook { () ⇒
      Future.successful(SystemMetrics.stopCollecting())
    }
  }
}