How to use the nova.api.openstack.wsgi.expected_errors function in nova

    @wsgi.expected_errors((400, 403, 404))
    @validation.schema(image_metadata.update)
    def update(self, req, image_id, id, body):
        context = req.environ['nova.context']

        meta = body['meta']

        if id not in meta:
            expl = _('Request body and URI mismatch')
            raise exc.HTTPBadRequest(explanation=expl)

        image = self._get_image(context, image_id)
        image['properties'][id] = meta[id]
        common.check_img_metadata_properties_quota(context,
                                                   image['properties'])
        try:
            self.image_api.update(context, image_id, image, data=None,

    @wsgi.expected_errors(400)
    @validation.schema(assisted_volume_snapshots.snapshots_create)
    def create(self, req, body):
        """Creates a new snapshot."""
        context = req.environ['nova.context']
        context.can(avs_policies.POLICY_ROOT % 'create')

        snapshot = body['snapshot']
        create_info = snapshot['create_info']
        volume_id = snapshot['volume_id']

        try:
            return self.compute_api.volume_snapshot_create(context, volume_id,
                                                           create_info)
        except (exception.VolumeBDMNotFound,
                exception.VolumeBDMIsMultiAttach,
                exception.InvalidVolume) as error:

    @wsgi.expected_errors((404, 409))
    def delete(self, req, id):
        """Destroys a server."""
        try:
            self._delete(req.environ['nova.context'], req, id)
        except exception.InstanceNotFound:
            msg = _("Instance could not be found")
            raise exc.HTTPNotFound(explanation=msg)
        except (exception.InstanceIsLocked,
                exception.AllocationDeleteFailed) as e:
            raise exc.HTTPConflict(explanation=e.format_message())
        except exception.InstanceInvalidState as state_error:
            common.raise_http_conflict_for_instance_invalid_state(state_error,
                    'delete', id)

    @wsgi.expected_errors(409)
    @wsgi.response(200)
    @validation.schema(schema.create)
    def create(self, req, body):
        """Creates a new agent build."""
        context = req.environ['nova.context']
        context.can(agents_policies.BASE_POLICY_NAME)

        agent = body['agent']
        hypervisor = agent['hypervisor']
        os = agent['os']
        architecture = agent['architecture']
        version = agent['version']
        url = agent['url']
        md5hash = agent['md5hash']

        agent_obj = objects.Agent(context=context)

    @wsgi.expected_errors((400, 404, 501))
    @validation.schema(hosts.update)
    def update(self, req, id, body):
        """Return booleanized version of body dict.

        :param Request req: The request object (containing 'nova-context'
                            env var).
        :param str id: The host name.
        :param dict body: example format {'host': {'status': 'enable',
                          'maintenance_mode': 'enable'}}
        :return: Same dict as body but 'enable' strings for 'status' and
                 'maintenance_mode' are converted into True, else False.
        :rtype: dict
        """
        def read_enabled(orig_val):
            # Convert enable/disable str to a bool.
            val = orig_val.strip().lower()

    @wsgi.expected_errors((400, 404, 409))
    @wsgi.response(202)
    @wsgi.action('removeSecurityGroup')
    def _removeSecurityGroup(self, req, id, body):
        context = req.environ['nova.context']
        context.can(sg_policies.BASE_POLICY_NAME)

        group_name = self._parse(body, 'removeSecurityGroup')

        try:
            return self._invoke(self.security_group_api.remove_from_instance,
                                context, id, group_name)
        except (exception.SecurityGroupNotFound,
                exception.InstanceNotFound) as exp:
            raise exc.HTTPNotFound(explanation=exp.format_message())
        except exception.NoUniqueMatch as exp:
            raise exc.HTTPConflict(explanation=exp.format_message())

    @wsgi.expected_errors((400, 404, 409))
    @wsgi.action('evacuate')
    @validation.schema(evacuate.evacuate, "2.0", "2.13")
    @validation.schema(evacuate.evacuate_v214, "2.14", "2.28")
    @validation.schema(evacuate.evacuate_v2_29, "2.29", "2.67")
    @validation.schema(evacuate.evacuate_v2_68, "2.68")
    def _evacuate(self, req, id, body):
        """Permit admins to evacuate a server from a failed host
        to a new one.
        """
        context = req.environ["nova.context"]
        instance = common.get_instance(self.compute_api, context, id)
        context.can(evac_policies.BASE_POLICY_NAME,
                    target={'user_id': instance.user_id,
                            'project_id': instance.project_id})

        evacuate_body = body["evacuate"]

    @wsgi.expected_errors((404, 409, 501))
    @wsgi.action('unrescue')
    def _unrescue(self, req, id, body):
        """Unrescue an instance."""
        context = req.environ["nova.context"]
        context.can(rescue_policies.BASE_POLICY_NAME)
        instance = common.get_instance(self.compute_api, context, id)
        try:
            self.compute_api.unrescue(context, instance)
        except exception.InstanceUnknownCell as e:
            raise exc.HTTPNotFound(explanation=e.format_message())
        except exception.InstanceIsLocked as e:
            raise exc.HTTPConflict(explanation=e.format_message())
        except exception.InstanceInvalidState as state_error:
            common.raise_http_conflict_for_instance_invalid_state(state_error,
                                                                  'unrescue',
                                                                  id)

    @wsgi.expected_errors((404, 409))
    @wsgi.action('shelveOffload')
    def _shelve_offload(self, req, id, body):
        """Force removal of a shelved instance from the compute node."""
        context = req.environ["nova.context"]
        context.can(shelve_policies.POLICY_ROOT % 'shelve_offload')

        instance = common.get_instance(self.compute_api, context, id)
        try:
            self.compute_api.shelve_offload(context, instance)
        except exception.InstanceUnknownCell as e:
            raise exc.HTTPNotFound(explanation=e.format_message())
        except exception.InstanceIsLocked as e:
            raise exc.HTTPConflict(explanation=e.format_message())
        except exception.InstanceInvalidState as state_error:
            common.raise_http_conflict_for_instance_invalid_state(state_error,
                                                              'shelveOffload',

    @wsgi.expected_errors(())
    @validation.query_schema(quota_sets.query_schema_275, '2.75')
    @validation.query_schema(quota_sets.query_schema, '2.0', '2.74')
    @wsgi.response(202)
    def delete(self, req, id):
        context = req.environ['nova.context']
        context.can(qs_policies.POLICY_ROOT % 'delete', {'project_id': id})
        params = urlparse.parse_qs(req.environ.get('QUERY_STRING', ''))
        user_id = params.get('user_id', [None])[0]
        if user_id:
            objects.Quotas.destroy_all_by_project_and_user(
                context, id, user_id)
        else:
            objects.Quotas.destroy_all_by_project(context, id)