[cs615asa] HW3 Getting the hostname

[Rob Hoffmann]

Question about retrieving the hostname in the helper tool.

Since the images take some time to boot up, ec2-run-instances does not 
necessarily return the hostname right away. A logical way of getting it 
would be to keep calling ec2-describe-instances <instance> until a 
hostname is returned in the description. However I didn't want to put 
the ec2-describe-instances in an infinite loop as an instance boot 
failure on Amazon's end would leave the user with a hanging script which 
wasn't their fault.

Currently my script runs the describe command X number of times before 
it "times out", but I'm not sure if this is a good approach as some AMIs 
may take longer to boot than others and X might end up being too small. 
Is there another way I should be looking at this issue? Should I simply 
trust that the instances will always boot?

-Rob