https://docs.aws.amazon.com/autoscaling/ec2/userguide/as-scaling-target-tracking.html
https://docs.aws.amazon.com/autoscaling/ec2/userguide/as-instance-monitoring.html#enable-as-instance-metrics
https://www.terraform.io/docs/providers/aws/r/appautoscaling_policy.html
https://docs.aws.amazon.com/AmazonECS/latest/developerguide/service-auto-scaling.html