Packer for single source AMI configuration

I talk about boot strapping on this blog post:
http://cloudconclave.blogspot.com/2013/08/boot-strapping-with-user-data-and.html

Another method of single source configuration for EC2 instances without getting into the dilemma of 'AMI sprawl' is to use Packer. More on the use of Packer here:
http://blog.controlgroup.com/2013/10/21/packer-cloudformation-power-couple/

AWS EC2 IP address of running instance

Can use a number of methods, but these are the two that I use:
1: /sbin/ifconfig
2: wget -q -O - http://169.254.169.254/latest/meta-data/local-ipv4

The wget option assumes wget is installed. If it is not, you can issue this command to install it (as root):
 yum -y install wget