def createService()

in common/scala/src/main/scala/org/apache/openwhisk/core/yarn/YARNContainerFactory.scala [139:218]
66 lines of code
11 McCabe index (conditional complexity)

  def createService(): Unit = {
    logging.info(this, "Creating Service with images: " + images.map(i => i.resolveImageName()).mkString(", "))

    val componentList = images
      .map(
        i =>
          ComponentDefinition(
            i.name.replace('.', '-'), //name must be [a-z][a-z0-9-]*
            Some(0), //start with zero containers
            Some(runCommand),
            Option.empty,
            Some(ArtifactDefinition(i.resolveImageName(), "DOCKER")),
            Some(ResourceDefinition(yarnConfig.cpus, yarnConfig.memory)),
            Some(ConfigurationDefinition(Map(("YARN_CONTAINER_RUNTIME_DOCKER_RUN_OVERRIDE_DISABLE", "true")))),
            List[String]()))
      .toList

    //Add kerberos def if necessary
    var kerberosDef: Option[KerberosPrincipalDefinition] = None
    if (yarnConfig.authType.equals(YARNRESTUtil.KERBEROSAUTH))
      kerberosDef = Some(
        KerberosPrincipalDefinition(Some(yarnConfig.kerberosPrincipal), Some(yarnConfig.kerberosKeytab)))

    val service = ServiceDefinition(
      Some(serviceName),
      Some(version),
      Some(description),
      Some("STABLE"),
      Some(yarnConfig.queue),
      componentList,
      kerberosDef)

    //Submit service
    val response =
      YARNRESTUtil.submitRequestWithAuth(
        yarnConfig.authType,
        HttpMethods.POST,
        s"${yarnConfig.masterUrl}/app/v1/services",
        service.toJson.compactPrint)

    //Handle response
    response match {
      case httpresponse(StatusCodes.OK, content) =>
        logging.info(this, s"Service submitted. Response: $content")

      case httpresponse(StatusCodes.Accepted, content) =>
        logging.info(this, s"Service submitted. Response: $content")

      case httpresponse(_, _) => YARNRESTUtil.handleYARNRESTError(logging)
    }

    //Wait for service start (up to serviceStartTimeoutMS milliseconds)
    var started = false
    var retryCount = 0
    val maxRetryCount = serviceStartTimeoutMS / retryWaitMS
    while (!started && retryCount < maxRetryCount) {
      val serviceDef =
        YARNRESTUtil.downloadServiceDefinition(yarnConfig.authType, serviceName, yarnConfig.masterUrl)(logging)

      if (serviceDef == null) {
        logging.info(this, "Service not found yet")
        Thread.sleep(retryWaitMS)
      } else {
        serviceDef.state.getOrElse(None) match {
          case "STABLE" | "STARTED" =>
            logging.info(this, "YARN service achieved stable state")
            started = true

          case state =>
            logging.info(
              this,
              s"YARN service is not in stable state yet ($retryCount/$maxRetryCount). Current state: $state")
            Thread.sleep(retryWaitMS)
        }
      }
      retryCount += 1
    }
    if (!started)
      throw new Exception(s"After ${serviceStartTimeoutMS}ms YARN service did not achieve stable state")
  }