Comment 2 for bug 1108040

Also related, from the doc comments:
Hi Anne. Well this part didn't work, I spent quite a bit of time troubleshooting why cloud_init was failing and I finally sorted it out. Somewhere in the documentation (either in the controller node documentation or where you refer to the quantum script for creating the private network that the controller needs to know how to route to that network so that it can reply to the http://169.154.169.154 request for metadata. The easiest way to do this is to run:
route add -net 10.5.5.0 netmask 255.255.255.0 dev eth1 gw 192.168.0.2

or even use 10.0.0.0 netmask 255.0.0.0 dev eth1 gw 192.168.0.2 if you plan on creating lots of networks.

replacing eth0 for whatever interface your management network is on. Without this, cloud_init will fail because all replies from the metadata service will go to whatever the default gateway on the controller is set to.