Stopping EC2 instance when custom cloudwatch metric passes limit

Question

I'm trying to find a way to make an Amazon EC2 instance stop automatically when a certain custom metric on CloudWatch passes a limit. So far if I've understood correctly based on these articles:

• Discussion Forum: Custom Metric EC2 Action
• CloudWatch Documentation: Create Alarms to Stop, Terminate, Reboot, or Recover an Instance

This will only work if the metric is defined as follows:

• Tied to certain instance
• With type of System/Linux

However in my case I have a custom metric that is actually not instance-related but "global" and if a certain limit is passed, I would need to stop all instances, no matter from which instance the limiting log is received.

Does anybody know if there is way to make this work? What I'd need is some way to make CloudWatch work like this:

• If arbitrary custom metric value passes a certain limit -> stop defined instances not tied to the metric itself.

The main problem is that the EC2 option is greyed out as the metric is not tied to certain EC2 instance and I'm not sure if there's any way to do this without actually making the metric itself certain instance related.

Answer 1

Have the custom CloudWatch metric post alerts to an SNS topic.

Have the SNS topic trigger a Lambda function that shuts down your EC2 instances via a call to the AWS API.