I have created two Alarms to scale up my instance count,
Then I have created a Composite alarm to go to ALARM state if Alarm 1 or 2 Triggered. Now I want to remove the above-mentioned Alarms from Scaling policies and use the composite alarm for Auto Scaling. Is it possible? If so, how can we do it?
when we want to create custom alerts with mutliple metrics we can use math expressions. for ex: i want to create an alert with the combination of mem and cpu utilization so check the both mem and cpu metrics of service and click on the Add math -> conditional -> AND . then it will give you a new metric like e1 expression. and also we can edit that expression by using if conditions.
math expression example e1: IF( m1 < 30 && c1 < 30 , 1,0) which means when memory avg and cpu avg are less than 30 then only you graph on 1 else go to 0. now you can setup alarm between 0 and 1 and add an action to this alaram.
As Milan has already mentioned, composite alarms cannot be used in autoscaling policies. However, you can make a conditional alarm (if cpu>20 || target response >10) for 'n' minutes, go in alarm state. This way you can use this alarm in your autoscaling policy.
