With EC2 auto scaling, when using a step scaling policy (as opposed to a simple scaling policy) that scales in due to an alarm that is based on an AWS/EC2 metric (e.g. CPUUtilization <= 30%) with detailed CloudWatch monitoring disabled, when my auto scaling group scales in, it scales in two instances in short succession, without waiting for the metric to update. How can I prevent the auto scaling group from scaling in too fast for the metric to update?
Edit: here was last night’s scaling history. At 5:15, 5:17, 5:19, 5:21 UTC, auto scaling scaled in due to low CPU Utilization, even though CPU Utilization only has data points at 5:10, 5:15, 5:20, and the scaling event should have ceased after the 5:15 datapoint. There appears to be no way to adjust the cooldown duration of step scaling policy scale ins (step scaling policies ignore the Default Cooldown (=600s) and only scale out policies have estimated instance warmup).