use python-novaclient to manage openstack vm

http://albertomolina.wordpress.com/2013/11/20/how-to-launch-an-instance-on-openstack-iii-python-novaclient-library/

Allocate Floating IP to project

Floating IPs (elastic IPs in Amazon EC2 terminology) allow instances to talk to an external host or access to the instances from an external network. A floating IP can be allocated to a project before or after launching an instance, we’ll do it before.

We need to know available floating IP pools:

>>> nova.floating_ip_pools. list ()
[<FloatingIPPool: name = ext_net>]

A list containing only one pool is shown (‘ext_net’). So let’s request a floating IP to ext_net and store the result (a FloatingIP object) in the variable “floating_ip”:

>>> floating_ip = nova.floating_ips.create(nova.floating_ip_pools.list()[0].name)

We can see IP allocated to project:

>>> floating_ip.ip
u '172.22.196.59'