diff --git a/nova/api/openstack/compute/plugins/v3/agents.py b/nova/api/openstack/compute/plugins/v3/agents.py
index 285d196a3d1..da6297c36df 100644
--- a/nova/api/openstack/compute/plugins/v3/agents.py
+++ b/nova/api/openstack/compute/plugins/v3/agents.py
@@ -168,5 +168,6 @@ def get_resources(self):
 
     def get_controller_extensions(self):
         """It's an abstract function V3APIExtensionBase and the extension
-        will not be loaded without it."""
+        will not be loaded without it.
+        """
         return []
diff --git a/nova/api/openstack/compute/plugins/v3/coverage.py b/nova/api/openstack/compute/plugins/v3/coverage.py
index 9f21caac8bd..b8e1ec6be0e 100644
--- a/nova/api/openstack/compute/plugins/v3/coverage.py
+++ b/nova/api/openstack/compute/plugins/v3/coverage.py
@@ -39,9 +39,9 @@
 authorize = extensions.extension_authorizer('compute', 'v3:' + ALIAS)
 CONF = cfg.CONF
 
+
 def _import_coverage():
-    """ This function ensure loading coverage module from python-coverage.
-    """
+    """This function ensure loading coverage module from python-coverage."""
     try:
         path = sys.path[:]
         if os.getcwd() in path:
diff --git a/nova/api/openstack/compute/plugins/v3/extension_info.py b/nova/api/openstack/compute/plugins/v3/extension_info.py
index c626f6104ad..e862054c31a 100644
--- a/nova/api/openstack/compute/plugins/v3/extension_info.py
+++ b/nova/api/openstack/compute/plugins/v3/extension_info.py
@@ -69,7 +69,7 @@ def _translate(self, ext):
         return ext_data
 
     def _get_extensions(self, context):
-        """Filter extensions list based on policy"""
+        """Filter extensions list based on policy."""
 
         discoverable_extensions = dict()
         for alias, ext in self.extension_info.get_extensions().iteritems():
@@ -78,7 +78,8 @@ def _get_extensions(self, context):
             if authorize(context, action='discoverable'):
                 discoverable_extensions[alias] = ext
             else:
-                LOG.debug(_("Filter out extension %s from discover list"), alias)
+                LOG.debug(_("Filter out extension %s from discover list"),
+                          alias)
         return discoverable_extensions
 
     @wsgi.serializers(xml=ExtensionsTemplate)
diff --git a/nova/api/openstack/compute/plugins/v3/flavors.py b/nova/api/openstack/compute/plugins/v3/flavors.py
index 31c0fa8b746..57125ad4507 100644
--- a/nova/api/openstack/compute/plugins/v3/flavors.py
+++ b/nova/api/openstack/compute/plugins/v3/flavors.py
@@ -146,7 +146,7 @@ def _get_flavors(self, req):
 
 
 class Flavors(extensions.V3APIExtensionBase):
-    """ Flavors Extension. """
+    """Flavors Extension."""
     name = "flavors"
     alias = "flavors"
     namespace = "http://docs.openstack.org/compute/core/flavors/v3"
diff --git a/nova/api/openstack/compute/plugins/v3/hosts.py b/nova/api/openstack/compute/plugins/v3/hosts.py
index e0ea1203b20..88f351120cb 100644
--- a/nova/api/openstack/compute/plugins/v3/hosts.py
+++ b/nova/api/openstack/compute/plugins/v3/hosts.py
@@ -201,7 +201,8 @@ def read_enabled(orig_val, msg):
 
     def _set_host_maintenance(self, context, host_name, mode=True):
         """Start/Stop host maintenance window. On start, it triggers
-        guest VMs evacuation."""
+        guest VMs evacuation.
+        """
         LOG.audit(_("Putting host %(host_name)s in maintenance mode "
                     "%(mode)s."),
                   {'host_name': host_name, 'mode': mode})
@@ -219,7 +220,8 @@ def _set_host_maintenance(self, context, host_name, mode=True):
     def _set_enabled_status(self, context, host_name, enabled):
         """Sets the specified host's ability to accept new instances.
         :param enabled: a boolean - if False no new VMs will be able to start
-        on the host"""
+                        on the host.
+        """
         if enabled:
             LOG.audit(_("Enabling host %s.") % host_name)
         else:
diff --git a/nova/api/openstack/compute/plugins/v3/instance_usage_audit_log.py b/nova/api/openstack/compute/plugins/v3/instance_usage_audit_log.py
index d74c999153b..93327b3c5cf 100644
--- a/nova/api/openstack/compute/plugins/v3/instance_usage_audit_log.py
+++ b/nova/api/openstack/compute/plugins/v3/instance_usage_audit_log.py
@@ -138,5 +138,6 @@ def get_resources(self):
 
     def get_controller_extensions(self):
         """It's an abstract function V3APIExtensionBase and the extension
-        will not be loaded without it."""
+        will not be loaded without it.
+        """
         return []
diff --git a/nova/api/openstack/compute/plugins/v3/scheduler_hints.py b/nova/api/openstack/compute/plugins/v3/scheduler_hints.py
index 142c7bb6488..4c01baa3afc 100644
--- a/nova/api/openstack/compute/plugins/v3/scheduler_hints.py
+++ b/nova/api/openstack/compute/plugins/v3/scheduler_hints.py
@@ -21,6 +21,7 @@
 
 ALIAS = "os-scheduler-hints"
 
+
 class SchedulerHintsController(wsgi.Controller):
 
     @staticmethod
diff --git a/nova/api/openstack/compute/plugins/v3/servers.py b/nova/api/openstack/compute/plugins/v3/servers.py
index bca1994408d..57f1d1ac096 100644
--- a/nova/api/openstack/compute/plugins/v3/servers.py
+++ b/nova/api/openstack/compute/plugins/v3/servers.py
@@ -462,7 +462,7 @@ def check_whiteblack_lists(ext):
                 # Check whitelist is either empty or if not then the extension
                 # is in the whitelist
                 if (not CONF.osapi_v3.extensions_whitelist or
-                    ext.obj.alias in CONF.osapi_v3.extensions_whitelist):
+                        ext.obj.alias in CONF.osapi_v3.extensions_whitelist):
 
                     # Check the extension is not in the blacklist
                     if ext.obj.alias not in CONF.osapi_v3.extensions_blacklist:
diff --git a/nova/api/openstack/compute/plugins/v3/simple_tenant_usage.py b/nova/api/openstack/compute/plugins/v3/simple_tenant_usage.py
index e386b02f829..491e3f58af2 100644
--- a/nova/api/openstack/compute/plugins/v3/simple_tenant_usage.py
+++ b/nova/api/openstack/compute/plugins/v3/simple_tenant_usage.py
@@ -289,5 +289,6 @@ def get_resources(self):
 
     def get_controller_extensions(self):
         """It's an abstract function V3APIExtensionBase and the extension
-        will not be loaded without it."""
+        will not be loaded without it.
+        """
         return []
diff --git a/nova/tests/api/openstack/compute/plugins/v3/test_cells.py b/nova/tests/api/openstack/compute/plugins/v3/test_cells.py
index f369c06e3b0..65b14e7606b 100644
--- a/nova/tests/api/openstack/compute/plugins/v3/test_cells.py
+++ b/nova/tests/api/openstack/compute/plugins/v3/test_cells.py
@@ -19,7 +19,6 @@
 from webob import exc
 
 from nova.api.openstack.compute.plugins.v3 import cells as cells_ext
-from nova.api.openstack import extensions
 from nova.api.openstack import xmlutil
 from nova.cells import rpcapi as cells_rpcapi
 from nova import context
diff --git a/nova/tests/api/openstack/compute/plugins/v3/test_config_drive.py b/nova/tests/api/openstack/compute/plugins/v3/test_config_drive.py
index 98be4ce1bee..fc5efba3ba7 100644
--- a/nova/tests/api/openstack/compute/plugins/v3/test_config_drive.py
+++ b/nova/tests/api/openstack/compute/plugins/v3/test_config_drive.py
@@ -19,8 +19,8 @@
 from oslo.config import cfg
 import webob
 
-from nova.api.openstack.compute.plugins.v3 import config_drive
 from nova.api.openstack.compute import plugins
+from nova.api.openstack.compute.plugins.v3 import config_drive
 from nova.api.openstack.compute.plugins.v3 import servers
 from nova.compute import api as compute_api
 from nova.compute import flavors
@@ -62,7 +62,7 @@ def test_show(self):
         req = webob.Request.blank('/v3/servers/1')
         req.headers['Content-Type'] = 'application/json'
         response = req.get_response(fakes.wsgi_app_v3(
-            init_only=('servers','os-config-drive')))
+            init_only=('servers', 'os-config-drive')))
         self.assertEquals(response.status_int, 200)
         res_dict = jsonutils.loads(response.body)
         self.assertTrue('config_drive' in res_dict['server'])
@@ -141,7 +141,7 @@ def instance_update(context, uuid, values):
         def rpc_call_wrapper(context, topic, msg, timeout=None):
             """Stub out the scheduler creating the instance entry."""
             if (topic == CONF.scheduler_topic and
-                msg['method'] == 'run_instance'):
+                    msg['method'] == 'run_instance'):
                 request_spec = msg['args']['request_spec']
                 num_instances = request_spec.get('num_instances', 1)
                 instances = []
@@ -213,8 +213,8 @@ def create(*args, **kwargs):
             return old_create(*args, **kwargs)
 
         self.stubs.Set(compute_api.API, 'create', create)
-        self._test_create_extra(params, override_controller
-                                =self.no_config_drive_controller)
+        self._test_create_extra(params,
+            override_controller=self.no_config_drive_controller)
 
     def test_create_instance_with_config_drive(self):
         def create(*args, **kwargs):
@@ -324,4 +324,3 @@ def test_request_with_config_drive(self):
             },
         }
         self.assertEquals(request['body'], expected)
-
diff --git a/nova/tests/api/openstack/compute/plugins/v3/test_extension_info.py b/nova/tests/api/openstack/compute/plugins/v3/test_extension_info.py
index a19d2806449..1a5ba4154cb 100644
--- a/nova/tests/api/openstack/compute/plugins/v3/test_extension_info.py
+++ b/nova/tests/api/openstack/compute/plugins/v3/test_extension_info.py
@@ -40,9 +40,11 @@ def __init__(self, name, alias, description, namespace, version):
                            'ext3 namespace', 1)
 }
 
+
 def fake_policy_enforce(context, action, target, do_raise=True):
     return True
 
+
 def fake_policy_enforce_selective(context, action, target, do_raise=True):
     if action == 'compute_extension:v3:ext1-alias:discoverable':
         raise exception.NotAuthorized
diff --git a/nova/tests/api/openstack/compute/plugins/v3/test_flavor_access.py b/nova/tests/api/openstack/compute/plugins/v3/test_flavor_access.py
index 7d9ec93df24..bbbaf8df8e0 100644
--- a/nova/tests/api/openstack/compute/plugins/v3/test_flavor_access.py
+++ b/nova/tests/api/openstack/compute/plugins/v3/test_flavor_access.py
@@ -18,8 +18,8 @@
 from lxml import etree
 from webob import exc
 
-from nova.api.openstack.compute.plugins.v3 import flavor_access
 from nova.api.openstack.compute import flavors as flavors_api
+from nova.api.openstack.compute.plugins.v3 import flavor_access
 from nova.compute import flavors
 from nova import context
 from nova import exception
diff --git a/nova/tests/api/openstack/compute/plugins/v3/test_hypervisors.py b/nova/tests/api/openstack/compute/plugins/v3/test_hypervisors.py
index 393e8fba41b..8c45f40a175 100644
--- a/nova/tests/api/openstack/compute/plugins/v3/test_hypervisors.py
+++ b/nova/tests/api/openstack/compute/plugins/v3/test_hypervisors.py
@@ -17,7 +17,6 @@
 from webob import exc
 
 from nova.api.openstack.compute.plugins.v3 import hypervisors
-from nova import context
 from nova import db
 from nova.db.sqlalchemy import api as db_api
 from nova import exception
@@ -324,8 +323,8 @@ def test_uptime_non_integer_id(self):
 
     def test_uptime_non_admin(self):
         req = fakes.HTTPRequestV3.blank('/os-hypervisors/1/uptime')
-        self.assertRaises(exception.PolicyNotAuthorized, self.controller.uptime,
-                          req, '1')
+        self.assertRaises(exception.PolicyNotAuthorized,
+                          self.controller.uptime, req, '1')
 
     def test_search(self):
         req = fakes.HTTPRequestV3.blank('/os-hypervisors/hyper/search',
diff --git a/nova/tests/api/openstack/compute/plugins/v3/test_images.py b/nova/tests/api/openstack/compute/plugins/v3/test_images.py
index 712e3c8a576..264a7d90944 100644
--- a/nova/tests/api/openstack/compute/plugins/v3/test_images.py
+++ b/nova/tests/api/openstack/compute/plugins/v3/test_images.py
@@ -649,8 +649,10 @@ def detail(self, *args, **kwargs):
                 raise exception.Invalid('meow')
 
         request = fakes.HTTPRequestV3.blank('/v3/os-images?marker=invalid')
-        controller = images.ImagesController(image_service=InvalidImageService())
-        self.assertRaises(webob.exc.HTTPBadRequest, controller.detail, request)
+        controller = images.ImagesController(
+                                image_service=InvalidImageService())
+        self.assertRaises(webob.exc.HTTPBadRequest, controller.detail,
+                          request)
 
     def test_generate_alternate_link(self):
         view = images_view.ViewBuilder()
diff --git a/nova/tests/api/openstack/compute/plugins/v3/test_quota_sets.py b/nova/tests/api/openstack/compute/plugins/v3/test_quota_sets.py
index 48dee4f442a..3fdbf79572e 100644
--- a/nova/tests/api/openstack/compute/plugins/v3/test_quota_sets.py
+++ b/nova/tests/api/openstack/compute/plugins/v3/test_quota_sets.py
@@ -20,7 +20,6 @@
 import webob
 
 from nova.api.openstack.compute.plugins.v3 import quota_sets as quotas
-from nova.api.openstack import extensions
 from nova.api.openstack import wsgi
 from nova import context as context_maker
 from nova import quota
diff --git a/nova/tests/api/openstack/compute/plugins/v3/test_scheduler_hints.py b/nova/tests/api/openstack/compute/plugins/v3/test_scheduler_hints.py
index 049b3ec6b53..b35b21eeb2b 100644
--- a/nova/tests/api/openstack/compute/plugins/v3/test_scheduler_hints.py
+++ b/nova/tests/api/openstack/compute/plugins/v3/test_scheduler_hints.py
@@ -180,7 +180,7 @@ def instance_update(context, uuid, values):
         def rpc_call_wrapper(context, topic, msg, timeout=None):
             """Stub out the scheduler creating the instance entry."""
             if (topic == CONF.scheduler_topic and
-                msg['method'] == 'run_instance'):
+                    msg['method'] == 'run_instance'):
                 request_spec = msg['args']['request_spec']
                 num_instances = request_spec.get('num_instances', 1)
                 instances = []
@@ -253,8 +253,8 @@ def create(*args, **kwargs):
             return old_create(*args, **kwargs)
 
         self.stubs.Set(compute_api.API, 'create', create)
-        self._test_create_extra(params, override_controller
-                                =self.no_scheduler_hints_controller)
+        self._test_create_extra(params,
+                override_controller=self.no_scheduler_hints_controller)
 
     def test_create_instance_with_scheduler_hints_enabled(self):
         hints = {'a': 'b'}
@@ -268,6 +268,7 @@ def create(*args, **kwargs):
         self.stubs.Set(compute_api.API, 'create', create)
         self._test_create_extra(params)
 
+
 class TestServerCreateRequestXMLDeserializer(test.TestCase):
 
     def setUp(self):
@@ -306,4 +307,3 @@ def test_request_with_scheduler_hints_and_alternate_namespace_prefix(self):
             }
         }
         self.assertEquals(request['body'], expected)
-
diff --git a/nova/tests/api/openstack/compute/plugins/v3/test_server_diagnostics.py b/nova/tests/api/openstack/compute/plugins/v3/test_server_diagnostics.py
index 61b78fea87e..ff6b8ee80e5 100644
--- a/nova/tests/api/openstack/compute/plugins/v3/test_server_diagnostics.py
+++ b/nova/tests/api/openstack/compute/plugins/v3/test_server_diagnostics.py
@@ -45,7 +45,8 @@ def setUp(self):
                        fake_get_diagnostics)
         self.stubs.Set(compute_api.API, 'get', fake_instance_get)
 
-        self.router = compute.APIRouterV3(init_only=('servers', 'os-server-diagnostics'))
+        self.router = compute.APIRouterV3(init_only=('servers',
+                                                     'os-server-diagnostics'))
 
     def test_get_diagnostics(self):
         req = fakes.HTTPRequestV3.blank(
diff --git a/nova/tests/api/openstack/compute/plugins/v3/test_servers.py b/nova/tests/api/openstack/compute/plugins/v3/test_servers.py
index 66642868911..cbadbe3b256 100644
--- a/nova/tests/api/openstack/compute/plugins/v3/test_servers.py
+++ b/nova/tests/api/openstack/compute/plugins/v3/test_servers.py
@@ -234,7 +234,8 @@ def test_get_server_by_uuid(self):
 
     def test_unique_host_id(self):
         """Create two servers with the same host and different
-           project_ids and check that the hostId's are unique"""
+        project_ids and check that the hostId's are unique.
+        """
         def return_instance_with_host(self, *args):
             project_id = str(uuid.uuid4())
             return fakes.stub_instance(id=1, uuid=FAKE_UUID,
diff --git a/tox.ini b/tox.ini
index dcdd4bc3922..a46d87dbd6d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -41,7 +41,7 @@ commands = {posargs}
 [flake8]
 ignore = E121,E122,E123,E124,E126,E127,E128,E711,E712,H302,H303,H404,F403,F811,F841,N309
 builtins = _
-exclude =  .venv,.git,.tox,dist,doc,*openstack/common*,*lib/python*,*egg,build,plugins,tools
+exclude =  .venv,.git,.tox,dist,doc,*openstack/common*,*lib/python*,*egg,build,*plugins/xenserver*,tools
 
 [hacking]
 local-check-factory = nova.hacking.checks.factory