def create(self, req, body):
        """Creates a new instance event."""
        context = req.environ['nova.context']
        authorize(context, action='create')

        response_events = []
        accepted_events = []
        accepted_instances = set()
        instances = {}
        result = 200

        body_events = body.get('events', [])
        if not isinstance(body_events, list) or not len(body_events):
            raise webob.exc.HTTPBadRequest()

        for _event in body_events:
            client_event = dict(_event)
            event = objects.InstanceExternalEvent(context)

            status = client_event.get('status', 'completed')
            if status not in external_event_obj.EVENT_STATUSES:
                raise webob.exc.HTTPBadRequest(
                    _('Invalid event status `%s\'') % status)

            if client_event.get('name') not in external_event_obj.EVENT_NAMES:
                raise webob.exc.HTTPBadRequest(
                    _('Invalid event name %s') % client_event.get('name'))

            try:
                event.instance_uuid = client_event.pop('server_uuid')
                event.name = client_event.pop('name')
                event.status = client_event.pop('status', 'completed')
                event.tag = client_event.pop('tag', None)
            except __HOLE__ as missing_key:
                msg = _('event entity requires key %(key)s') % missing_key
                raise webob.exc.HTTPBadRequest(explanation=msg)

            if client_event:
                msg = (_('event entity contains unsupported items: %s') %
                       ', '.join(client_event.keys()))
                raise webob.exc.HTTPBadRequest(explanation=msg)

            instance = instances.get(event.instance_uuid)
            if not instance:
                try:
                    instance = objects.Instance.get_by_uuid(
                        context, event.instance_uuid)
                    instances[event.instance_uuid] = instance
                except exception.InstanceNotFound:
                    LOG.debug('Dropping event %(name)s:%(tag)s for unknown '
                              'instance %(instance_uuid)s',
                              {'name': event.name, 'tag': event.tag,
                               'instance_uuid': event.instance_uuid})
                    _event['status'] = 'failed'
                    _event['code'] = 404
                    result = 207

            # NOTE: before accepting the event, make sure the instance
            # for which the event is sent is assigned to a host; otherwise
            # it will not be possible to dispatch the event
            if instance:
                if instance.host:
                    accepted_events.append(event)
                    accepted_instances.add(instance)
                    LOG.info(_LI('Creating event %(name)s:%(tag)s for '
                                 'instance %(instance_uuid)s'),
                              {'name': event.name, 'tag': event.tag,
                               'instance_uuid': event.instance_uuid})
                    # NOTE: as the event is processed asynchronously verify
                    # whether 202 is a more suitable response code than 200
                    _event['status'] = 'completed'
                    _event['code'] = 200
                else:
                    LOG.debug("Unable to find a host for instance "
                              "%(instance)s. Dropping event %(event)s",
                              {'instance': event.instance_uuid,
                               'event': event.name})
                    _event['status'] = 'failed'
                    _event['code'] = 422
                    result = 207

            response_events.append(_event)

        if accepted_events:
            self.compute_api.external_instance_event(
                context, accepted_instances, accepted_events)
        else:
            msg = _('No instances found for any event')
            raise webob.exc.HTTPNotFound(explanation=msg)

        # FIXME(cyeoh): This needs some infrastructure support so that
        # we have a general way to do this
        robj = wsgi.ResponseObject({'events': response_events})
        robj._code = result
        return robj
dataset/ETHPy150Open BU-NU-CLOUD-SP16/Trusted-Platform-Module-nova/nova/api/openstack/compute/legacy_v2/contrib/server_external_events.py/ServerExternalEventsController.create