Auto Scaling – CloudWatch Alarms & Scaling

• An Auto Scaling Group (ASG) can adjust its capacity automatically based on Amazon CloudWatch alarms.

• A CloudWatch alarm tracks a specific metric (e.g., Average CPU Utilization, request count, or a custom metric).

• For metrics like Average CPU Utilization, the value is aggregated across all instances in the ASG.

Scaling Actions

• Scale-out policy – Launch additional instances when the alarm signals increased load.

• Scale-in policy – Terminate instances when the alarm signals reduced load.