AWS EC2 autoscaling without constant alarms?

3
votes

I have created the following two alerts for an autoscaling group:

  • Scale up 1 instance if "CPUUtilization >= 75%" changes to state ALARM
  • Scale down 1 instance if "CPUUtilization >= 30%" changes to state OK

I have chosen to trigger the scale down event on OK to not have a constant ALARM in Cloudwatch if load is below 30%. On the other hand that is exactly the issue. When an upscale happens leaving the group with an average load between 30% and 75% the state is set to ALARM.

Is there any way to configure Cloudwatch to trigger scale up and down events properly without being left with an ALARM state after the scaling happened?

1
amazon-web-servicesamazon-ec2autoscaling
Shouldn't it be like this: CPUUtilization <= 30%" changes to state OK? – Mahdi
The alarm fires when CPU >= 30%, so I need to downscale when the state changes to OK (which happens when CPU < 30%). – kev
@kev Did you manage to find something? I'd also like a better solution. – musiKk
@musiKk unfortunately not – kev

1 Answers

0
votes

The "Scale down" operation should be set to "CPUUtilization < 75%" (state OK), and don't worry about leaving the group without machines, though you have a min number of instances and it does not go beyond that.