I've got an app running on AWS. How do I set up Amazon CloudWatch to notify me when the EC2 instance fails or is no longer responsive?
I went through the CloudWatch screens, and it appears that you can monitor certain statistics, like CPU or disk utilization, but I didn't see a way to monitor an event like "the instance got an http request and took more than X seconds to respond."
Amazon's Route 53 Health Check is the right tool for the job.
Route 53 can monitor the health and performance of your application as well as your web servers and other resources.
You can set up HTTP resource checks in Route 53 that will trigger an e-mail notification if the server is down or responding with an error.
http://eladnava.com/monitoring-http-health-email-alerts-aws/