Why scale in matrics not created when using terraform autoscaling?

Question

I am using terraform as IAC,

I have the following policy:

resource "aws_appautoscaling_policy" "ecs_policy_cpu" {
  name               = "cpu-autoscaling"
  policy_type        = "TargetTrackingScaling"
  resource_id        = aws_appautoscaling_target.ecs_target.resource_id
  scalable_dimension = aws_appautoscaling_target.ecs_target.scalable_dimension
  service_namespace  = aws_appautoscaling_target.ecs_target.service_namespace

  target_tracking_scaling_policy_configuration {
   predefined_metric_specification {
     predefined_metric_type = "ECSServiceAverageCPUUtilization"
   }

  target_value       = var.autoscaling_cpu_target
  scale_in_cooldown  = 120
  scale_out_cooldown = 120
  }
}

The ECS indeed has an autoscaling policy and I can observe that the system scale when the load is high, but the system do not scale down after the load end. After talking to the AWS support team it seems that terraform do not create the scale in policy( metric) only the scale out, did anyone encountered it?

thx

Answer 1

You need to create 2 policies, scale up and scale down.