Packstack Installation with Existing External Network / kickstart RHEL7 (CentOS7)

Interested in getting OpenStack up and running within few hours in the easiest possible way? Then Packstack is most probably your friend. Indeed, Packstack is a utility which leverages on Puppet modules to deploy various parts of OpenStack on multiple pre-installed servers over SSH automatically. I've been through a cycle of building/destroying my OpenStack Labs by using this tool and I'm willing to share below a Kickstart File which fully automate such type of Installation (OpenStack using PackStack with an Existing External Network). The initial process on which I built this KickStart Installation is well documented here. My main aim here is to be able to reference a Single Kickstart File during my RHEL/CentOS 7 Installation and have OpenStack Installed and partly configured without manual Intervention (except for a reboot that I preferred not to automate :-) ).

The same Kickstart File can also be used as a Template for RHEL7/CentOS7 (or any other Systemd-based's distribution), especially if there's a need to run some script (or any other program) during the first boot (after OS installation) of the System (see the %post section).
In fact, in this Kickstart File I've edited and created a Systemd service that will run only once after the first boot and delete itself.
I was used to do that on previous RHEL/CentOS (RHEL6...) by leveraging on /etc/rc.local. Though there’s still /etc/rc.local  on RHEL7,It is highly advisable to create own systemd services or udev rules to run scripts during boot instead of using that file.

Note that after the initial reboot, Packstack Configuration Progress can be followed using journalctl (journalctl -f -u pacstack_installation.service) 

Few Things that are specific to this Kickstart:
System Hostname: stiv-opsctr01
System IP:
System GW: 
PROXY and Install Server (I'm using proxy for Internet Access) :

My Kickstart File: