terraform example of app autoscaling based on customized metric specification

main.tf

resource "aws_appautoscaling_policy" "scale_out" {
  name                    = "scale-up"
  policy_type             = "TargetTrackingScaling"
  resource_id             = "service/${data.terraform_remote_state.ecs_cluster.ecs_cluster_name}/${var.service_name}"
  scalable_dimension      = "ecs:service:DesiredCount"
  service_namespace       = "ecs"

   target_tracking_scaling_policy_configuration {
    target_value = "${var.scaling_target_value}"
    scale_in_cooldown = "${var.scale_in_cooldown}"
    scale_out_cooldown = "${var.scale_out_cooldown}"

    customized_metric_specification {
      dimensions = {
        name = "ClusterName"
        value = "${data.terraform_remote_state.ecs_cluster.ecs_cluster_name}"
      }
      dimensions = {
        name = "ServiceName"
        value = "${var.service_name}"
      }
      #CPUUtilization
      metric_name  = "${var.scaling_metric_name}"
      namespace = "AWS/ECS"
      #Maximum
      statistic = "${var.scaling_metric_statistic}"
      unit = "Percent"
    }
  }
}