Sometimes my application dies w/o any reason and I can detect that using CloudWatch and CPU usage metric going down. At this moment I want to restart the java application or the whole EC2 instance. Any suggestions how can I achive that?
You can let CloudWatch terminate your EC2 instance and let AutoScaling bring up another "fresh" instance with your application configured.
AWS CloudWatch now provides a reboot EC2 instance action.
If only your application halt but EC2 instance works.
You could write a shell monitor the app using CloudWatch API and shoot the app when necessary,then make it a task in cron. Or you can using a shell right in your EC2 instance.
To restart your EC2 instance automatically is way too dangerous ,you can try Autoscaling, which automatically starts a new instance when your instance frozen and keep your SLA.
来源：https://stackoverflow.com/questions/13389737/how-to-restart-ec2-instance-from-cloudwatch-alarm