Getting Upstart to start services when an interface is up on Centos 6

Apparently upstart is not fully integrated to Centos 6.

For instance having a service like:

start on (net-device-up INTERFACE=lo)

will not work.

The solution which maintains compatibility with updates:

Create /sbin/ifup-local:

#!/bin/sh
initctl emit --no-wait net-device-up INTERFACE=$1

and make it executable.