EC2 Auto scaling

Question

I have one EC2 instance and running a tomcat service on the EC2 machine. I know, how to configure auto scaling when the CPU usage goes up, ... But, not sure how to configure auto scaling to launch a new instance when my tomcat service goes down even the EC2 instance is up. Also how to configure auto scaling when the tomcat service is hung even the tomcat process is up and running. If this is not possible with Ec2 auto scaling, Is this possible with ELB and Beanstalk?

Answer 1

If you go to the auto scaling page in the web console and click edit, you can choose either ec2 or elb health check. Ec2 monitors instance performance characteristics. Elb health checks can be used to monitor server response. As the name implies the auto scaling health status is controlled by the response given to a load balancer. This could be a tcp check to port 80 that just checks that the server is there, listening and responding, all the way up to a custom http check to a page you define, eg You could do hostname/myserverstatus and at that page have a script that checks server status, database availability etc, and then return either a success or error. See http://docs.aws.amazon.com/AutoScaling/latest/DeveloperGuide/as-add-elb-healthcheck.html

Good Luck!

Answer 2

There are some standard unix tools that do that for you. Upstart will watch your server and restart if it goes down. I don't know about it hanging. If you run on beanstalk, you can set up a call that the load balancer will make to see if your app is responsive, and it can then message you to let you know there is a problem. You can probably set it up to reboot the box, or restart the process.