Waiting for EC2 instance to launch and be in running state

Question

I am writing a program using AWS Java SDK to create EC2 instances and do some processing once they are launched.

I have written the following code but I know there could be a better way to do this:

public static void main(String[] args) {

   // Some code initialization here
   Instance ec2instance; 

   do {    
        try {
              Thread.sleep(sleep_cyle);
            } catch (InterruptedException ex) {
                System.out.println(ex.getMessage());
            }

       } while(ec2instance.getState().getCode() != 16);

       //Proceed with processing after instance is running
}

Thank you.

Answer 1

Since there is nothing reporting back to your application related to status changes, the only way to identify changes is to poll every 15-30 seconds.

There are rare cases where an instance may simply fail to launch. Your code should expect the possibility of going from pending to terminated.