ansible/ansible — pull request #518 by jpalley (2012-07-01 07:47:04+00:00)
Title: adds 'groups' variable, essentially making hosts file accessible as a var

Major use case:
When one server needs to be "aware" of other servers. Examples:
a) allows a template that is dependent upon how servers are configured in the hosts file: a config file for an app proxy/load balancer can see all of the servers in the [webapp] group in the host files and enumerate them in the config.
b) configure iptables to only accept incoming connections from a servers in a specific group.

I'm currently using this to setup hosts files, hadoop cluster, iptables

Note: It seems from the comments that keys aspect of the vars system are due for a re-factor. Its not clear to me if I've put this code in the right place?