def apply()

in pekko-sample-cluster-scala/src/main/scala/sample/cluster/stats/AppOneMaster.scala [20:57]
32 lines of code
3 McCabe index (conditional complexity)

    def apply(): Behavior[Nothing] = Behaviors.setup[Nothing] { ctx =>
      val cluster = Cluster(ctx.system)

      val singletonSettings = ClusterSingletonSettings(ctx.system)
        .withRole("compute")
      val serviceSingleton = SingletonActor(
        Behaviors.setup[StatsService.Command] { ctx =>
          // the service singleton accesses available workers through a group router
          val workersRouter =
            ctx.spawn(
              Routers
                .group(WorkerServiceKey)
                // the worker has a per word cache, so send the same word to the same worker
                .withConsistentHashingRouting(1, _.word),
              "WorkersRouter")

          StatsService(workersRouter)
        },
        "StatsService").withStopMessage(StatsService.Stop)
        .withSettings(singletonSettings)
      val serviceProxy = ClusterSingleton(ctx.system).init(serviceSingleton)

      if (cluster.selfMember.hasRole("compute")) {
        // on every compute node N local workers, which a cluster singleton stats service delegates work to
        val numberOfWorkers =
          ctx.system.settings.config.getInt("stats-service.workers-per-node")
        ctx.log.info("Starting {} workers", numberOfWorkers)
        (0 to numberOfWorkers).foreach { n =>
          val worker = ctx.spawn(StatsWorker(), s"StatsWorker$n")
          ctx.system.receptionist ! Receptionist
            .Register(WorkerServiceKey, worker)
        }
      }
      if (cluster.selfMember.hasRole("client")) {
        ctx.spawn(StatsClient(serviceProxy), "Client")
      }
      Behaviors.empty
    }