What is auto-scaling, and what metrics commonly trigger scaling decisions for a Node.js service running in the cloud?

Auto-scaling automatically adjusts running instance count based on demand -- common triggers include CPU utilization, memory usage, request latency, and queue depth for background-job services, since a growing backlog signals worker capacity falling behind incoming volume.

{
  "TargetValue": 60.0,
  "PredefinedMetricSpecification": { "PredefinedMetricType": "ECSServiceAverageCPUUtilization" },
  "ScaleOutCooldown": 60,
  "ScaleInCooldown": 300
}