Alarms are objects that define a condition for Autoscaler. Each alarm is meant to monitor a metric for threshold violation against a defined threshold condition (upper or lower).
When a metric value breaches its defined threshold boundary, the system will trigger an event causing a notification to be sent from the alarm evaluator Red5CloudWatchClient to the Autoscaler component. The alarm may carry additional data about the reporting Node or NodeGroup and an
action tag implying what action should be taken by the Autoscaler.
To see how to change alarm thresholds checkout Stream Manager API Documentation