Openstack: extending an nova api extensions

class ExtendedHostController(object):
    """The Hosts API controller for the OpenStack API."""
    def __init__(self):
        self.api = compute.HostAPI()
        super(ExtendedHostController, self).__init__()

    @wsgi.extends
    def show(self, req, resp_obj, id):
        """ patch to add all available information of a host. """
        host = id
        context = req.environ['nova.context']
        service_ref = db.service_get_all_compute_by_host(context, host)[0]
        compute_ref = service_ref['compute_node'][0]
        try:
            cpu_info = json.loads(compute_ref['cpu_info'])
        except:
            cpu_info = False
        resp_obj['host'].append({'resource':
                                  {'host': host,
                                   'project': 'status',
                                   'state': compute_ref['state'],
                                   'workload': compute_ref['current_workload'],
                                   'running_vms': compute_ref['running_vms'],
                                   'cpu_info': cpu_info,
                                   'hypervisor_type': compute_ref.hypervisor_type,
                                   'hypervisor_version': compute_ref.hypervisor_version,
                                   'hypervisor_hostname': compute_ref.hypervisor_hostname}})




class Hosts_state(extensions.ExtensionDescriptor):
    """Extensions for hosts"""
    name = "Hosts State Extension"
    alias = "EY-HOSTS-STATE"
    namespace = "http://docs.openstack.org/compute/ext/hosts/api/v1.1"
    updated = "2012-08-30T00:00:00+00:00"

    def get_controller_extensions(self):
        controller = ExtendedHostController()
        extension = extensions.ControllerExtension(self, 'os-hosts', controller)
        return [extension]