When using the RequestCountPerTarget metric for scaling in an Auto Scaling group, the behavior of

instance scaling follows specific rules set by Auto Scaling policies and cooldown periods:

Scaling Trigger: The Auto Scaling group triggers a scaling action whenever the

RequestCountPerTarget exceeds the predefined limit set in the scaling policy.

Cooldown Period: After launching an EC2 instance due to a scaling action, the Auto Scaling group

enters a cooldown period. During this period, despite further breaches of the threshold, no

additional instances will be launched. This is designed to give the newly launched instance time to

start and begin handling traffic, preventing the Auto Scaling group from launching too many

instances too quickly.

This mechanism helps maintain efficient use of resources by adapting to changes in load while

avoiding rapid, unnecessary scaling actions.