diff --git a/tox.ini b/tox.ini
index 39b10db23..c24be108a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -55,7 +55,7 @@ filename = *.py,app.wsgi
 show-source=True
 ignore= H105,E123,E226,N320,H202
 builtins= _
-enable-extensions = H106,H203
+enable-extensions = H106,H203,H904
 exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build,*sqlalchemy/alembic/versions/*,demo/,releasenotes
 
 [testenv:wheel]
diff --git a/watcher/applier/actions/migration.py b/watcher/applier/actions/migration.py
index d0b6dcf3d..b1679b409 100644
--- a/watcher/applier/actions/migration.py
+++ b/watcher/applier/actions/migration.py
@@ -113,8 +113,10 @@ class Migrate(base.BaseAction):
                                                 dest_hostname=destination)
         except nova_helper.nvexceptions.ClientException as e:
             LOG.debug("Nova client exception occurred while live "
-                      "migrating instance %s.Exception: %s" %
-                      (self.instance_uuid, e))
+                      "migrating instance "
+                      "%(instance)s.Exception: %(exception)s",
+                      {'instance': self.instance_uuid, 'exception': e})
+
         except Exception as e:
             LOG.exception(e)
             LOG.critical("Unexpected error occurred. Migration failed for "
diff --git a/watcher/cmd/api.py b/watcher/cmd/api.py
index 214cfc255..8e85a0c54 100644
--- a/watcher/cmd/api.py
+++ b/watcher/cmd/api.py
@@ -40,10 +40,10 @@ def main():
 
     if host == '127.0.0.1':
         LOG.info('serving on 127.0.0.1:%(port)s, '
-                 'view at %(protocol)s://127.0.0.1:%(port)s' %
+                 'view at %(protocol)s://127.0.0.1:%(port)s',
                  dict(protocol=protocol, port=port))
     else:
-        LOG.info('serving on %(protocol)s://%(host)s:%(port)s' %
+        LOG.info('serving on %(protocol)s://%(host)s:%(port)s',
                  dict(protocol=protocol, host=host, port=port))
 
     api_schedule = scheduling.APISchedulingService()
diff --git a/watcher/common/cinder_helper.py b/watcher/common/cinder_helper.py
index 8d483a535..126bc8e7c 100644
--- a/watcher/common/cinder_helper.py
+++ b/watcher/common/cinder_helper.py
@@ -139,13 +139,13 @@ class CinderHelper(object):
             volume = self.get_volume(volume.id)
             time.sleep(retry_interval)
             retry -= 1
-            LOG.debug("retry count: %s" % retry)
-            LOG.debug("Waiting to complete deletion of volume %s" % volume.id)
+            LOG.debug("retry count: %s", retry)
+            LOG.debug("Waiting to complete deletion of volume %s", volume.id)
         if self._can_get_volume(volume.id):
-            LOG.error("Volume deletion error: %s" % volume.id)
+            LOG.error("Volume deletion error: %s", volume.id)
             return False
 
-        LOG.debug("Volume %s was deleted successfully." % volume.id)
+        LOG.debug("Volume %s was deleted successfully.", volume.id)
         return True
 
     def check_migrated(self, volume, retry_interval=10):
@@ -179,8 +179,7 @@ class CinderHelper(object):
             LOG.error(error_msg)
             return False
         LOG.debug(
-            "Volume migration succeeded : "
-            "volume %s is now on host '%s'." % (
+            "Volume migration succeeded : volume %s is now on host '%s'.", (
                 volume.id, host_name))
         return True
 
@@ -194,8 +193,8 @@ class CinderHelper(object):
                 message=(_("Volume type must be same for migrating")))
 
         source_node = getattr(volume, 'os-vol-host-attr:host')
-        LOG.debug("Volume %s found on host '%s'."
-                  % (volume.id, source_node))
+        LOG.debug("Volume %s found on host '%s'.",
+                  (volume.id, source_node))
 
         self.cinder.volumes.migrate_volume(
             volume, dest_node, False, True)
@@ -211,8 +210,8 @@ class CinderHelper(object):
 
         source_node = getattr(volume, 'os-vol-host-attr:host')
         LOG.debug(
-            "Volume %s found on host '%s'." % (
-                volume.id, source_node))
+            "Volume %s found on host '%s'.",
+            (volume.id, source_node))
 
         self.cinder.volumes.retype(
             volume, dest_type, "on-demand")
@@ -234,14 +233,14 @@ class CinderHelper(object):
             LOG.debug('Waiting volume creation of {0}'.format(new_volume))
             time.sleep(retry_interval)
             retry -= 1
-            LOG.debug("retry count: %s" % retry)
+            LOG.debug("retry count: %s", retry)
 
         if getattr(new_volume, 'status') != 'available':
             error_msg = (_("Failed to create volume '%(volume)s. ") %
                          {'volume': new_volume.id})
             raise Exception(error_msg)
 
-        LOG.debug("Volume %s was created successfully." % new_volume)
+        LOG.debug("Volume %s was created successfully.", new_volume)
         return new_volume
 
     def delete_volume(self, volume):
diff --git a/watcher/common/nova_helper.py b/watcher/common/nova_helper.py
index 53639f8a7..f99ac09cf 100644
--- a/watcher/common/nova_helper.py
+++ b/watcher/common/nova_helper.py
@@ -106,7 +106,7 @@ class NovaHelper(object):
             return True
         else:
             LOG.debug("confirm resize failed for the "
-                      "instance %s" % instance.id)
+                      "instance %s", instance.id)
             return False
 
     def wait_for_volume_status(self, volume, status, timeout=60,
@@ -154,19 +154,20 @@ class NovaHelper(object):
         """
         new_image_name = ""
         LOG.debug(
-            "Trying a non-live migrate of instance '%s' " % instance_id)
+            "Trying a non-live migrate of instance '%s' ", instance_id)
 
         # Looking for the instance to migrate
         instance = self.find_instance(instance_id)
         if not instance:
-            LOG.debug("Instance %s not found !" % instance_id)
+            LOG.debug("Instance %s not found !", instance_id)
             return False
         else:
             # NOTE: If destination node is None call Nova API to migrate
             # instance
             host_name = getattr(instance, "OS-EXT-SRV-ATTR:host")
             LOG.debug(
-                "Instance %s found on host '%s'." % (instance_id, host_name))
+                "Instance %(instance)s found on host '%(host)s'.",
+                {'instance': instance_id, 'host': host_name})
 
             if dest_hostname is None:
                 previous_status = getattr(instance, 'status')
@@ -186,12 +187,12 @@ class NovaHelper(object):
                         return False
                     LOG.debug(
                         "cold migration succeeded : "
-                        "instance %s is now on host '%s'." % (
+                        "instance %s is now on host '%s'.", (
                             instance_id, new_hostname))
                     return True
                 else:
                     LOG.debug(
-                        "cold migration for instance %s failed" % instance_id)
+                        "cold migration for instance %s failed", instance_id)
                     return False
 
             if not keep_original_image_name:
@@ -220,7 +221,7 @@ class NovaHelper(object):
 
             for network_name, network_conf_obj in addresses.items():
                 LOG.debug(
-                    "Extracting network configuration for network '%s'" %
+                    "Extracting network configuration for network '%s'",
                     network_name)
 
                 network_names_list.append(network_name)
@@ -241,7 +242,7 @@ class NovaHelper(object):
             stopped_ok = self.stop_instance(instance_id)
 
             if not stopped_ok:
-                LOG.debug("Could not stop instance: %s" % instance_id)
+                LOG.debug("Could not stop instance: %s", instance_id)
                 return False
 
             # Building the temporary image which will be used
@@ -251,7 +252,7 @@ class NovaHelper(object):
 
             if not image_uuid:
                 LOG.debug(
-                    "Could not build temporary image of instance: %s" %
+                    "Could not build temporary image of instance: %s",
                     instance_id)
                 return False
 
@@ -299,8 +300,10 @@ class NovaHelper(object):
                     blocks.append(
                         block_device_mapping_v2_item)
 
-                    LOG.debug("Detaching volume %s from instance: %s" % (
-                        volume_id, instance_id))
+                    LOG.debug(
+                        "Detaching volume %(volume)s from "
+                        "instance: %(instance)s",
+                        {'volume': volume_id, 'instance': instance_id})
                     # volume.detach()
                     self.nova.volumes.delete_server_volume(instance_id,
                                                            volume_id)
@@ -308,11 +311,12 @@ class NovaHelper(object):
                     if not self.wait_for_volume_status(volume, "available", 5,
                                                        10):
                         LOG.debug(
-                            "Could not detach volume %s from instance: %s" % (
-                                volume_id, instance_id))
+                            "Could not detach volume %(volume)s "
+                            "from instance: %(instance)s",
+                            {'volume': volume_id, 'instance': instance_id})
                         return False
                 except ciexceptions.NotFound:
-                    LOG.debug("Volume '%s' not found " % image_id)
+                    LOG.debug("Volume '%s' not found ", image_id)
                     return False
 
             # We create the new instance from
@@ -331,18 +335,21 @@ class NovaHelper(object):
             if not new_instance:
                 LOG.debug(
                     "Could not create new instance "
-                    "for non-live migration of instance %s" % instance_id)
+                    "for non-live migration of instance %s", instance_id)
                 return False
 
             try:
-                LOG.debug("Detaching floating ip '%s' from instance %s" % (
-                    floating_ip, instance_id))
+                LOG.debug(
+                    "Detaching floating ip '%(floating_ip)s' "
+                    "from instance %(instance)s",
+                    {'floating_ip': floating_ip, 'instance': instance_id})
                 # We detach the floating ip from the current instance
                 instance.remove_floating_ip(floating_ip)
 
                 LOG.debug(
-                    "Attaching floating ip '%s' to the new instance %s" % (
-                        floating_ip, new_instance.id))
+                    "Attaching floating ip '%(ip)s' to the new "
+                    "instance %(id)s",
+                    {'ip': floating_ip, 'id': new_instance.id})
 
                 # We attach the same floating ip to the new instance
                 new_instance.add_floating_ip(floating_ip)
@@ -354,12 +361,12 @@ class NovaHelper(object):
             # Deleting the old instance (because no more useful)
             delete_ok = self.delete_instance(instance_id)
             if not delete_ok:
-                LOG.debug("Could not delete instance: %s" % instance_id)
+                LOG.debug("Could not delete instance: %s", instance_id)
                 return False
 
             LOG.debug(
                 "Instance %s has been successfully migrated "
-                "to new host '%s' and its new id is %s." % (
+                "to new host '%s' and its new id is %s.", (
                     instance_id, new_host_name, new_instance.id))
 
             return True
@@ -376,8 +383,10 @@ class NovaHelper(object):
         :param instance_id: the unique id of the instance to resize.
         :param flavor: the name or ID of the flavor to resize to.
         """
-        LOG.debug("Trying a resize of instance %s to flavor '%s'" % (
-            instance_id, flavor))
+        LOG.debug(
+            "Trying a resize of instance %(instance)s to "
+            "flavor '%(flavor)s'",
+            {'instance': instance_id, 'flavor': flavor})
 
         # Looking for the instance to resize
         instance = self.find_instance(instance_id)
@@ -394,17 +403,17 @@ class NovaHelper(object):
                       "instance %s. Exception: %s", instance_id, e)
 
         if not flavor_id:
-            LOG.debug("Flavor not found: %s" % flavor)
+            LOG.debug("Flavor not found: %s", flavor)
             return False
 
         if not instance:
-            LOG.debug("Instance not found: %s" % instance_id)
+            LOG.debug("Instance not found: %s", instance_id)
             return False
 
         instance_status = getattr(instance, 'OS-EXT-STS:vm_state')
         LOG.debug(
-            "Instance %s is in '%s' status." % (instance_id,
-                                                instance_status))
+            "Instance %(id)s is in '%(status)s' status.",
+            {'id': instance_id, 'status': instance_status})
 
         instance.resize(flavor=flavor_id)
         while getattr(instance,
@@ -442,17 +451,20 @@ class NovaHelper(object):
                               destination_node is None, nova scheduler choose
                               the destination host
         """
-        LOG.debug("Trying to live migrate instance %s " % (instance_id))
+        LOG.debug(
+            "Trying a live migrate instance %(instance)s ",
+            {'instance': instance_id})
 
         # Looking for the instance to migrate
         instance = self.find_instance(instance_id)
         if not instance:
-            LOG.debug("Instance not found: %s" % instance_id)
+            LOG.debug("Instance not found: %s", instance_id)
             return False
         else:
             host_name = getattr(instance, 'OS-EXT-SRV-ATTR:host')
             LOG.debug(
-                "Instance %s found on host '%s'." % (instance_id, host_name))
+                "Instance %(instance)s found on host '%(host)s'.",
+                {'instance': instance_id, 'host': host_name})
 
             # From nova api version 2.25(Mitaka release), the default value of
             # block_migration is None which is mapped to 'auto'.
@@ -474,7 +486,7 @@ class NovaHelper(object):
                 if host_name != new_hostname and instance.status == 'ACTIVE':
                     LOG.debug(
                         "Live migration succeeded : "
-                        "instance %s is now on host '%s'." % (
+                        "instance %s is now on host '%s'.", (
                             instance_id, new_hostname))
                     return True
                 else:
@@ -485,7 +497,7 @@ class NovaHelper(object):
                     and retry:
                 instance = self.nova.servers.get(instance.id)
                 if not getattr(instance, 'OS-EXT-STS:task_state'):
-                    LOG.debug("Instance task state: %s is null" % instance_id)
+                    LOG.debug("Instance task state: %s is null", instance_id)
                     break
                 LOG.debug(
                     'Waiting the migration of {0}  to {1}'.format(
@@ -501,13 +513,13 @@ class NovaHelper(object):
 
             LOG.debug(
                 "Live migration succeeded : "
-                "instance %s is now on host '%s'." % (
-                    instance_id, host_name))
+                "instance %(instance)s is now on host '%(host)s'.",
+                {'instance': instance_id, 'host': host_name})
 
             return True
 
     def abort_live_migrate(self, instance_id, source, destination, retry=240):
-        LOG.debug("Aborting live migration of instance %s" % instance_id)
+        LOG.debug("Aborting live migration of instance %s", instance_id)
         migration = self.get_running_migration(instance_id)
         if migration:
             migration_id = getattr(migration[0], "id")
@@ -520,7 +532,7 @@ class NovaHelper(object):
                 LOG.exception(e)
         else:
             LOG.debug(
-                "No running migrations found for instance %s" % instance_id)
+                "No running migrations found for instance %s", instance_id)
 
         while retry:
             instance = self.nova.servers.get(instance_id)
@@ -585,7 +597,7 @@ class NovaHelper(object):
         host = self.nova.hosts.get(hostname)
 
         if not host:
-            LOG.debug("host not found: %s" % hostname)
+            LOG.debug("host not found: %s", hostname)
             return False
         else:
             host[0].update(
@@ -607,18 +619,19 @@ class NovaHelper(object):
             key-value pairs to associate to the image as metadata.
         """
         LOG.debug(
-            "Trying to create an image from instance %s ..." % instance_id)
+            "Trying to create an image from instance %s ...", instance_id)
 
         # Looking for the instance
         instance = self.find_instance(instance_id)
 
         if not instance:
-            LOG.debug("Instance not found: %s" % instance_id)
+            LOG.debug("Instance not found: %s", instance_id)
             return None
         else:
             host_name = getattr(instance, 'OS-EXT-SRV-ATTR:host')
             LOG.debug(
-                "Instance %s found on host '%s'." % (instance_id, host_name))
+                "Instance %(instance)s found on host '%(host)s'.",
+                {'instance': instance_id, 'host': host_name})
 
             # We need to wait for an appropriate status
             # of the instance before we can build an image from it
@@ -645,14 +658,15 @@ class NovaHelper(object):
                     if not image:
                         break
                     status = image.status
-                    LOG.debug("Current image status: %s" % status)
+                    LOG.debug("Current image status: %s", status)
 
                 if not image:
-                    LOG.debug("Image not found: %s" % image_uuid)
+                    LOG.debug("Image not found: %s", image_uuid)
                 else:
                     LOG.debug(
-                        "Image %s successfully created for instance %s" % (
-                            image_uuid, instance_id))
+                        "Image %(image)s successfully created for "
+                        "instance %(instance)s",
+                        {'image': image_uuid, 'instance': instance_id})
                     return image_uuid
         return None
 
@@ -661,16 +675,16 @@ class NovaHelper(object):
 
         :param instance_id: the unique id of the instance to delete.
         """
-        LOG.debug("Trying to remove instance %s ..." % instance_id)
+        LOG.debug("Trying to remove instance %s ...", instance_id)
 
         instance = self.find_instance(instance_id)
 
         if not instance:
-            LOG.debug("Instance not found: %s" % instance_id)
+            LOG.debug("Instance not found: %s", instance_id)
             return False
         else:
             self.nova.servers.delete(instance_id)
-            LOG.debug("Instance %s removed." % instance_id)
+            LOG.debug("Instance %s removed.", instance_id)
             return True
 
     def stop_instance(self, instance_id):
@@ -678,21 +692,21 @@ class NovaHelper(object):
 
         :param instance_id: the unique id of the instance to stop.
         """
-        LOG.debug("Trying to stop instance %s ..." % instance_id)
+        LOG.debug("Trying to stop instance %s ...", instance_id)
 
         instance = self.find_instance(instance_id)
 
         if not instance:
-            LOG.debug("Instance not found: %s" % instance_id)
+            LOG.debug("Instance not found: %s", instance_id)
             return False
         elif getattr(instance, 'OS-EXT-STS:vm_state') == "stopped":
-            LOG.debug("Instance has been stopped: %s" % instance_id)
+            LOG.debug("Instance has been stopped: %s", instance_id)
             return True
         else:
             self.nova.servers.stop(instance_id)
 
             if self.wait_for_instance_state(instance, "stopped", 8, 10):
-                LOG.debug("Instance %s stopped." % instance_id)
+                LOG.debug("Instance %s stopped.", instance_id)
                 return True
             else:
                 return False
@@ -733,11 +747,11 @@ class NovaHelper(object):
             return False
 
         while instance.status not in status_list and retry:
-            LOG.debug("Current instance status: %s" % instance.status)
+            LOG.debug("Current instance status: %s", instance.status)
             time.sleep(sleep)
             instance = self.nova.servers.get(instance.id)
             retry -= 1
-        LOG.debug("Current instance status: %s" % instance.status)
+        LOG.debug("Current instance status: %s", instance.status)
         return instance.status in status_list
 
     def create_instance(self, node_id, inst_name="test", image_id=None,
@@ -753,26 +767,26 @@ class NovaHelper(object):
         It returns the unique id of the created instance.
         """
         LOG.debug(
-            "Trying to create new instance '%s' "
-            "from image '%s' with flavor '%s' ..." % (
-                inst_name, image_id, flavor_name))
+            "Trying to create new instance '%(inst)s' "
+            "from image '%(image)s' with flavor '%(flavor)s' ...",
+            {'inst': inst_name, 'image': image_id, 'flavor': flavor_name})
 
         try:
             self.nova.keypairs.findall(name=keypair_name)
         except nvexceptions.NotFound:
-            LOG.debug("Key pair '%s' not found " % keypair_name)
+            LOG.debug("Key pair '%s' not found ", keypair_name)
             return
 
         try:
             image = self.glance.images.get(image_id)
         except glexceptions.NotFound:
-            LOG.debug("Image '%s' not found " % image_id)
+            LOG.debug("Image '%s' not found ", image_id)
             return
 
         try:
             flavor = self.nova.flavors.find(name=flavor_name)
         except nvexceptions.NotFound:
-            LOG.debug("Flavor '%s' not found " % flavor_name)
+            LOG.debug("Flavor '%s' not found ", flavor_name)
             return
 
         # Make sure all security groups exist
@@ -780,7 +794,7 @@ class NovaHelper(object):
             group_id = self.get_security_group_id_from_name(sec_group_name)
 
             if not group_id:
-                LOG.debug("Security group '%s' not found " % sec_group_name)
+                LOG.debug("Security group '%s' not found ", sec_group_name)
                 return
 
         net_list = list()
@@ -789,7 +803,7 @@ class NovaHelper(object):
             nic_id = self.get_network_id_from_name(network_name)
 
             if not nic_id:
-                LOG.debug("Network '%s' not found " % network_name)
+                LOG.debug("Network '%s' not found ", network_name)
                 return
             net_obj = {"net-id": nic_id}
             net_list.append(net_obj)
@@ -815,14 +829,16 @@ class NovaHelper(object):
                 if create_new_floating_ip and instance.status == 'ACTIVE':
                     LOG.debug(
                         "Creating a new floating IP"
-                        " for instance '%s'" % instance.id)
+                        " for instance '%s'", instance.id)
                     # Creating floating IP for the new instance
                     floating_ip = self.nova.floating_ips.create()
 
                     instance.add_floating_ip(floating_ip)
 
-                    LOG.debug("Instance %s associated to Floating IP '%s'" % (
-                        instance.id, floating_ip.ip))
+                    LOG.debug(
+                        "Instance %(instance)s associated to "
+                        "Floating IP '%(ip)s'",
+                        {'instance': instance.id, 'ip': floating_ip.ip})
 
         return instance
 
@@ -896,7 +912,7 @@ class NovaHelper(object):
             LOG.debug('Waiting volume update to {0}'.format(new_volume))
             time.sleep(retry_interval)
             retry -= 1
-            LOG.debug("retry count: %s" % retry)
+            LOG.debug("retry count: %s", retry)
         if getattr(new_volume, 'status') != "in-use":
             LOG.error("Volume update retry timeout or error")
             return False
@@ -904,5 +920,6 @@ class NovaHelper(object):
         host_name = getattr(new_volume, "os-vol-host-attr:host")
         LOG.debug(
             "Volume update succeeded : "
-            "Volume %s is now on host '%s'." % (new_volume.id, host_name))
+            "Volume %s is now on host '%s'.",
+            (new_volume.id, host_name))
         return True
diff --git a/watcher/decision_engine/messaging/audit_endpoint.py b/watcher/decision_engine/messaging/audit_endpoint.py
index 54d47aed8..9f1a15fe2 100644
--- a/watcher/decision_engine/messaging/audit_endpoint.py
+++ b/watcher/decision_engine/messaging/audit_endpoint.py
@@ -48,7 +48,7 @@ class AuditEndpoint(object):
         self._oneshot_handler.execute(audit, context)
 
     def trigger_audit(self, context, audit_uuid):
-        LOG.debug("Trigger audit %s" % audit_uuid)
+        LOG.debug("Trigger audit %s", audit_uuid)
         self.executor.submit(self.do_trigger_audit,
                              context,
                              audit_uuid)
diff --git a/watcher/decision_engine/model/notification/cinder.py b/watcher/decision_engine/model/notification/cinder.py
index 7d305dcc8..5c7066b9a 100644
--- a/watcher/decision_engine/model/notification/cinder.py
+++ b/watcher/decision_engine/model/notification/cinder.py
@@ -255,7 +255,7 @@ class CapacityNotificationEndpoint(CinderNotification):
         ctxt.request_id = metadata['message_id']
         ctxt.project_domain = event_type
         LOG.info("Event '%(event)s' received from %(publisher)s "
-                 "with metadata %(metadata)s" %
+                 "with metadata %(metadata)s",
                  dict(event=event_type,
                       publisher=publisher_id,
                       metadata=metadata))
@@ -286,7 +286,7 @@ class VolumeCreateEnd(VolumeNotificationEndpoint):
         ctxt.request_id = metadata['message_id']
         ctxt.project_domain = event_type
         LOG.info("Event '%(event)s' received from %(publisher)s "
-                 "with metadata %(metadata)s" %
+                 "with metadata %(metadata)s",
                  dict(event=event_type,
                       publisher=publisher_id,
                       metadata=metadata))
@@ -311,7 +311,7 @@ class VolumeUpdateEnd(VolumeNotificationEndpoint):
         ctxt.request_id = metadata['message_id']
         ctxt.project_domain = event_type
         LOG.info("Event '%(event)s' received from %(publisher)s "
-                 "with metadata %(metadata)s" %
+                 "with metadata %(metadata)s",
                  dict(event=event_type,
                       publisher=publisher_id,
                       metadata=metadata))
@@ -369,7 +369,7 @@ class VolumeDeleteEnd(VolumeNotificationEndpoint):
         ctxt.request_id = metadata['message_id']
         ctxt.project_domain = event_type
         LOG.info("Event '%(event)s' received from %(publisher)s "
-                 "with metadata %(metadata)s" %
+                 "with metadata %(metadata)s",
                  dict(event=event_type,
                       publisher=publisher_id,
                       metadata=metadata))
diff --git a/watcher/decision_engine/model/notification/nova.py b/watcher/decision_engine/model/notification/nova.py
index 4ba6afaf5..b788113a2 100644
--- a/watcher/decision_engine/model/notification/nova.py
+++ b/watcher/decision_engine/model/notification/nova.py
@@ -229,7 +229,7 @@ class ServiceUpdated(VersionedNotificationEndpoint):
         ctxt.request_id = metadata['message_id']
         ctxt.project_domain = event_type
         LOG.info("Event '%(event)s' received from %(publisher)s "
-                 "with metadata %(metadata)s" %
+                 "with metadata %(metadata)s",
                  dict(event=event_type,
                       publisher=publisher_id,
                       metadata=metadata))
@@ -275,7 +275,7 @@ class InstanceCreated(VersionedNotificationEndpoint):
         ctxt.request_id = metadata['message_id']
         ctxt.project_domain = event_type
         LOG.info("Event '%(event)s' received from %(publisher)s "
-                 "with metadata %(metadata)s" %
+                 "with metadata %(metadata)s",
                  dict(event=event_type,
                       publisher=publisher_id,
                       metadata=metadata))
@@ -310,7 +310,7 @@ class InstanceUpdated(VersionedNotificationEndpoint):
         ctxt.request_id = metadata['message_id']
         ctxt.project_domain = event_type
         LOG.info("Event '%(event)s' received from %(publisher)s "
-                 "with metadata %(metadata)s" %
+                 "with metadata %(metadata)s",
                  dict(event=event_type,
                       publisher=publisher_id,
                       metadata=metadata))
@@ -337,7 +337,7 @@ class InstanceDeletedEnd(VersionedNotificationEndpoint):
         ctxt.request_id = metadata['message_id']
         ctxt.project_domain = event_type
         LOG.info("Event '%(event)s' received from %(publisher)s "
-                 "with metadata %(metadata)s" %
+                 "with metadata %(metadata)s",
                  dict(event=event_type,
                       publisher=publisher_id,
                       metadata=metadata))
@@ -372,7 +372,7 @@ class LegacyInstanceUpdated(UnversionedNotificationEndpoint):
         ctxt.request_id = metadata['message_id']
         ctxt.project_domain = event_type
         LOG.info("Event '%(event)s' received from %(publisher)s "
-                 "with metadata %(metadata)s" %
+                 "with metadata %(metadata)s",
                  dict(event=event_type,
                       publisher=publisher_id,
                       metadata=metadata))
@@ -399,7 +399,7 @@ class LegacyInstanceCreatedEnd(UnversionedNotificationEndpoint):
         ctxt.request_id = metadata['message_id']
         ctxt.project_domain = event_type
         LOG.info("Event '%(event)s' received from %(publisher)s "
-                 "with metadata %(metadata)s" %
+                 "with metadata %(metadata)s",
                  dict(event=event_type,
                       publisher=publisher_id,
                       metadata=metadata))
@@ -426,7 +426,7 @@ class LegacyInstanceDeletedEnd(UnversionedNotificationEndpoint):
         ctxt.request_id = metadata['message_id']
         ctxt.project_domain = event_type
         LOG.info("Event '%(event)s' received from %(publisher)s "
-                 "with metadata %(metadata)s" %
+                 "with metadata %(metadata)s",
                  dict(event=event_type,
                       publisher=publisher_id,
                       metadata=metadata))
@@ -459,7 +459,7 @@ class LegacyLiveMigratedEnd(UnversionedNotificationEndpoint):
         ctxt.request_id = metadata['message_id']
         ctxt.project_domain = event_type
         LOG.info("Event '%(event)s' received from %(publisher)s "
-                 "with metadata %(metadata)s" %
+                 "with metadata %(metadata)s",
                  dict(event=event_type,
                       publisher=publisher_id,
                       metadata=metadata))
@@ -486,7 +486,7 @@ class LegacyInstanceResizeConfirmEnd(UnversionedNotificationEndpoint):
         ctxt.request_id = metadata['message_id']
         ctxt.project_domain = event_type
         LOG.info("Event '%(event)s' received from %(publisher)s "
-                 "with metadata %(metadata)s" %
+                 "with metadata %(metadata)s",
                  dict(event=event_type,
                       publisher=publisher_id,
                       metadata=metadata))
@@ -513,7 +513,7 @@ class LegacyInstanceRebuildEnd(UnversionedNotificationEndpoint):
         ctxt.request_id = metadata['message_id']
         ctxt.project_domain = event_type
         LOG.info("Event '%(event)s' received from %(publisher)s "
-                 "with metadata %(metadata)s" %
+                 "with metadata %(metadata)s",
                  dict(event=event_type,
                       publisher=publisher_id,
                       metadata=metadata))
diff --git a/watcher/decision_engine/scoring/scoring_factory.py b/watcher/decision_engine/scoring/scoring_factory.py
index c716cff8f..6da59c5a1 100644
--- a/watcher/decision_engine/scoring/scoring_factory.py
+++ b/watcher/decision_engine/scoring/scoring_factory.py
@@ -91,16 +91,16 @@ def _reload_scoring_engines(refresh=False):
 
         for name in engines.keys():
             se_impl = default.DefaultScoringLoader().load(name)
-            LOG.debug("Found Scoring Engine plugin: %s" % se_impl.get_name())
+            LOG.debug("Found Scoring Engine plugin: %s", se_impl.get_name())
             _scoring_engine_map[se_impl.get_name()] = se_impl
 
         engine_containers = \
             default.DefaultScoringContainerLoader().list_available()
 
         for container_id, container_cls in engine_containers.items():
-            LOG.debug("Found Scoring Engine container plugin: %s" %
+            LOG.debug("Found Scoring Engine container plugin: %s",
                       container_id)
             for se in container_cls.get_scoring_engine_list():
-                LOG.debug("Found Scoring Engine plugin: %s" %
+                LOG.debug("Found Scoring Engine plugin: %s",
                           se.get_name())
                 _scoring_engine_map[se.get_name()] = se
diff --git a/watcher/decision_engine/strategy/strategies/basic_consolidation.py b/watcher/decision_engine/strategy/strategies/basic_consolidation.py
index 1a670fe1e..10006255b 100644
--- a/watcher/decision_engine/strategy/strategies/basic_consolidation.py
+++ b/watcher/decision_engine/strategy/strategies/basic_consolidation.py
@@ -277,7 +277,7 @@ class BasicConsolidation(base.ServerConsolidationBaseStrategy):
             resource_id = "%s_%s" % (node.uuid, node.hostname)
             LOG.error(
                 "No values returned by %(resource_id)s "
-                "for %(metric_name)s" % dict(
+                "for %(metric_name)s", dict(
                     resource_id=resource_id,
                     metric_name=self.METRIC_NAMES[
                         self.config.datasource]['host_cpu_usage']))
@@ -297,7 +297,7 @@ class BasicConsolidation(base.ServerConsolidationBaseStrategy):
         if instance_cpu_utilization is None:
             LOG.error(
                 "No values returned by %(resource_id)s "
-                "for %(metric_name)s" % dict(
+                "for %(metric_name)s", dict(
                     resource_id=instance.uuid,
                     metric_name=self.METRIC_NAMES[
                         self.config.datasource]['instance_cpu_usage']))
diff --git a/watcher/decision_engine/strategy/strategies/noisy_neighbor.py b/watcher/decision_engine/strategy/strategies/noisy_neighbor.py
index 8f10237ab..e4c51682c 100644
--- a/watcher/decision_engine/strategy/strategies/noisy_neighbor.py
+++ b/watcher/decision_engine/strategy/strategies/noisy_neighbor.py
@@ -199,10 +199,10 @@ class NoisyNeighbor(base.NoisyNeighborBaseStrategy):
                                 hosts_need_release[node.uuid] = {
                                     'priority_vm': potential_priority_instance,
                                     'noisy_vm': potential_noisy_instance}
-                                LOG.debug("Priority VM found: %s" % (
-                                    potential_priority_instance.uuid))
-                                LOG.debug("Noisy VM found: %s" % (
-                                    potential_noisy_instance.uuid))
+                                LOG.debug("Priority VM found: %s",
+                                          potential_priority_instance.uuid)
+                                LOG.debug("Noisy VM found: %s",
+                                          potential_noisy_instance.uuid)
                                 loop_break_flag = True
                                 break
 
diff --git a/watcher/decision_engine/strategy/strategies/outlet_temp_control.py b/watcher/decision_engine/strategy/strategies/outlet_temp_control.py
index 4f8519bca..467a5c2c4 100644
--- a/watcher/decision_engine/strategy/strategies/outlet_temp_control.py
+++ b/watcher/decision_engine/strategy/strategies/outlet_temp_control.py
@@ -194,7 +194,8 @@ class OutletTempControl(base.ThermalOptimizationBaseStrategy):
                 LOG.warning("%s: no outlet temp data", resource_id)
                 continue
 
-            LOG.debug("%s: outlet temperature %f" % (resource_id, outlet_temp))
+            LOG.debug("%(resource)s: outlet temperature %(temp)f",
+                      {'resource': resource_id, 'temp': outlet_temp})
             instance_data = {'node': node, 'outlet_temp': outlet_temp}
             if outlet_temp >= self.threshold:
                 # mark the node to release resources
diff --git a/watcher/decision_engine/strategy/strategies/uniform_airflow.py b/watcher/decision_engine/strategy/strategies/uniform_airflow.py
index c5f2e2bd5..0a4a436a4 100644
--- a/watcher/decision_engine/strategy/strategies/uniform_airflow.py
+++ b/watcher/decision_engine/strategy/strategies/uniform_airflow.py
@@ -318,7 +318,8 @@ class UniformAirflow(base.BaseStrategy):
                 LOG.warning("%s: no airflow data", resource_id)
                 continue
 
-            LOG.debug("%s: airflow %f" % (resource_id, airflow))
+            LOG.debug("%(resource)s: airflow %(airflow)f",
+                      {'resource': resource_id, 'airflow': airflow})
             nodemap = {'node': node, 'airflow': airflow}
             if airflow >= self.threshold_airflow:
                 # mark the node to release resources
diff --git a/watcher/decision_engine/strategy/strategies/vm_workload_consolidation.py b/watcher/decision_engine/strategy/strategies/vm_workload_consolidation.py
index 3b6c99fe5..2af96bab4 100644
--- a/watcher/decision_engine/strategy/strategies/vm_workload_consolidation.py
+++ b/watcher/decision_engine/strategy/strategies/vm_workload_consolidation.py
@@ -168,7 +168,7 @@ class VMWorkloadConsolidation(base.ServerConsolidationBaseStrategy):
             return instance.state.value
         else:
             LOG.error('Unexpected instance state type, '
-                      'state=%(state)s, state_type=%(st)s.' %
+                      'state=%(state)s, state_type=%(st)s.',
                       dict(state=instance.state,
                            st=type(instance.state)))
             raise exception.WatcherException
@@ -184,7 +184,7 @@ class VMWorkloadConsolidation(base.ServerConsolidationBaseStrategy):
             return node.status.value
         else:
             LOG.error('Unexpected node status type, '
-                      'status=%(status)s, status_type=%(st)s.' %
+                      'status=%(status)s, status_type=%(st)s.',
                       dict(status=node.status,
                            st=type(node.status)))
             raise exception.WatcherException
@@ -233,7 +233,7 @@ class VMWorkloadConsolidation(base.ServerConsolidationBaseStrategy):
             # migration mechanism to move non active VMs.
             LOG.error(
                 'Cannot live migrate: instance_uuid=%(instance_uuid)s, '
-                'state=%(instance_state)s.' % dict(
+                'state=%(instance_state)s.', dict(
                     instance_uuid=instance.uuid,
                     instance_state=instance_state_str))
             return
diff --git a/watcher/decision_engine/strategy/strategies/workload_stabilization.py b/watcher/decision_engine/strategy/strategies/workload_stabilization.py
index c7e36a50d..44f1dd935 100644
--- a/watcher/decision_engine/strategy/strategies/workload_stabilization.py
+++ b/watcher/decision_engine/strategy/strategies/workload_stabilization.py
@@ -203,7 +203,7 @@ class WorkloadStabilization(base.WorkloadStabilizationBaseStrategy):
             if avg_meter is None:
                 LOG.warning(
                     "No values returned by %(resource_id)s "
-                    "for %(metric_name)s" % dict(
+                    "for %(metric_name)s", dict(
                         resource_id=instance.uuid, metric_name=meter))
                 return
             if meter == 'cpu_util':
@@ -375,12 +375,12 @@ class WorkloadStabilization(base.WorkloadStabilizationBaseStrategy):
         normalized_load = self.normalize_hosts_load(hosts_load)
         for metric in self.metrics:
             metric_sd = self.get_sd(normalized_load, metric)
-            LOG.info("Standard deviation for %s is %s."
-                     % (metric, metric_sd))
+            LOG.info("Standard deviation for %s is %s.",
+                     (metric, metric_sd))
             if metric_sd > float(self.thresholds[metric]):
                 LOG.info("Standard deviation of %s exceeds"
-                         " appropriate threshold %s."
-                         % (metric, metric_sd))
+                         " appropriate threshold %s.",
+                         (metric, metric_sd))
                 return self.simulate_migrations(hosts_load)
 
     def add_migration(self,
diff --git a/watcher/decision_engine/strategy/strategies/zone_migration.py b/watcher/decision_engine/strategy/strategies/zone_migration.py
index 7e52e3970..0316bc8e8 100644
--- a/watcher/decision_engine/strategy/strategies/zone_migration.py
+++ b/watcher/decision_engine/strategy/strategies/zone_migration.py
@@ -312,7 +312,7 @@ class ZoneMigration(base.ZoneMigrationBaseStrategy):
                     else:
                         self.instances_migration(targets, action_counter)
 
-        LOG.debug("action total: %s, pools: %s, nodes %s " % (
+        LOG.debug("action total: %s, pools: %s, nodes %s ", (
                   action_counter.total_count,
                   action_counter.per_pool_count,
                   action_counter.per_node_count))
@@ -413,13 +413,13 @@ class ZoneMigration(base.ZoneMigrationBaseStrategy):
             pool = getattr(volume, 'os-vol-host-attr:host')
             if action_counter.is_pool_max(pool):
                 LOG.debug("%s has objects to be migrated, but it has"
-                          " reached the limit of parallelization." % pool)
+                          " reached the limit of parallelization.", pool)
                 continue
 
             src_type = volume.volume_type
             dst_pool, dst_type = self.get_dst_pool_and_type(pool, src_type)
             LOG.debug(src_type)
-            LOG.debug("%s %s" % (dst_pool, dst_type))
+            LOG.debug("%s %s", (dst_pool, dst_type))
 
             if self.is_available(volume):
                 if src_type == dst_type:
@@ -448,7 +448,7 @@ class ZoneMigration(base.ZoneMigrationBaseStrategy):
 
             if action_counter.is_node_max(src_node):
                 LOG.debug("%s has objects to be migrated, but it has"
-                          " reached the limit of parallelization." % src_node)
+                          " reached the limit of parallelization.", src_node)
                 continue
 
             dst_node = self.get_dst_node(src_node)
@@ -643,7 +643,7 @@ class ActionCounter(object):
         if not self.is_total_max() and not self.is_pool_max(pool):
             self.per_pool_count[pool] += 1
             self.total_count += 1
-            LOG.debug("total: %s, per_pool: %s" % (
+            LOG.debug("total: %s, per_pool: %s", (
                       self.total_count, self.per_pool_count))
             return True
         return False
@@ -660,7 +660,7 @@ class ActionCounter(object):
         if not self.is_total_max() and not self.is_node_max(node):
             self.per_node_count[node] += 1
             self.total_count += 1
-            LOG.debug("total: %s, per_node: %s" % (
+            LOG.debug("total: %s, per_node: %s", (
                       self.total_count, self.per_node_count))
             return True
         return False
@@ -679,9 +679,9 @@ class ActionCounter(object):
         """
         if pool not in self.per_pool_count:
             self.per_pool_count[pool] = 0
-        LOG.debug("the number of parallel per pool %s is %s " %
+        LOG.debug("the number of parallel per pool %s is %s ",
                   (pool, self.per_pool_count[pool]))
-        LOG.debug("per pool limit is %s" % self.per_pool_limit)
+        LOG.debug("per pool limit is %s", self.per_pool_limit)
         return self.per_pool_count[pool] >= self.per_pool_limit
 
     def is_node_max(self, node):
@@ -724,7 +724,7 @@ class BaseFilter(object):
             for k, v in six.iteritems(targets):
                 if not self.is_allowed(k):
                     continue
-                LOG.debug("filter:%s with the key: %s" % (cond, k))
+                LOG.debug("filter:%s with the key: %s", (cond, k))
                 targets[k] = self.exec_filter(v, cond)
 
         LOG.debug(targets)
@@ -778,7 +778,7 @@ class ProjectSortFilter(SortMovingToFrontFilter):
         """
 
         project_id = self.get_project_id(item)
-        LOG.debug("project_id: %s, sort_key: %s" % (project_id, sort_key))
+        LOG.debug("project_id: %s, sort_key: %s", (project_id, sort_key))
         return project_id == sort_key
 
     def get_project_id(self, item):
@@ -812,7 +812,7 @@ class ComputeHostSortFilter(SortMovingToFrontFilter):
         """
 
         host = self.get_host(item)
-        LOG.debug("host: %s, sort_key: %s" % (host, sort_key))
+        LOG.debug("host: %s, sort_key: %s", (host, sort_key))
         return host == sort_key
 
     def get_host(self, item):
@@ -840,7 +840,7 @@ class StorageHostSortFilter(SortMovingToFrontFilter):
         """
 
         host = self.get_host(item)
-        LOG.debug("host: %s, sort_key: %s" % (host, sort_key))
+        LOG.debug("host: %s, sort_key: %s", (host, sort_key))
         return host == sort_key
 
     def get_host(self, item):
@@ -867,7 +867,7 @@ class ComputeSpecSortFilter(BaseFilter):
         result = items
 
         if sort_key not in self.accept_keys:
-            LOG.warning("Invalid key is specified: %s" % sort_key)
+            LOG.warning("Invalid key is specified: %s", sort_key)
         else:
             result = self.get_sorted_items(items, sort_key)
 
@@ -912,11 +912,11 @@ class ComputeSpecSortFilter(BaseFilter):
         :returns: memory size of item
         """
 
-        LOG.debug("item: %s, flavors: %s" % (item, flavors))
+        LOG.debug("item: %s, flavors: %s", (item, flavors))
         for flavor in flavors:
-            LOG.debug("item.flavor: %s, flavor: %s" % (item.flavor, flavor))
+            LOG.debug("item.flavor: %s, flavor: %s", (item.flavor, flavor))
             if item.flavor.get('id') == flavor.id:
-                LOG.debug("flavor.ram: %s" % flavor.ram)
+                LOG.debug("flavor.ram: %s", flavor.ram)
                 return flavor.ram
 
     def get_vcpu_num(self, item, flavors):
@@ -927,11 +927,11 @@ class ComputeSpecSortFilter(BaseFilter):
         :returns: vcpu number of item
         """
 
-        LOG.debug("item: %s, flavors: %s" % (item, flavors))
+        LOG.debug("item: %s, flavors: %s", (item, flavors))
         for flavor in flavors:
-            LOG.debug("item.flavor: %s, flavor: %s" % (item.flavor, flavor))
+            LOG.debug("item.flavor: %s, flavor: %s", (item.flavor, flavor))
             if item.flavor.get('id') == flavor.id:
-                LOG.debug("flavor.vcpus: %s" % flavor.vcpus)
+                LOG.debug("flavor.vcpus: %s", flavor.vcpus)
                 return flavor.vcpus
 
     def get_disk_size(self, item, flavors):
@@ -942,11 +942,11 @@ class ComputeSpecSortFilter(BaseFilter):
         :returns: disk size of item
         """
 
-        LOG.debug("item: %s, flavors: %s" % (item, flavors))
+        LOG.debug("item: %s, flavors: %s", (item, flavors))
         for flavor in flavors:
-            LOG.debug("item.flavor: %s, flavor: %s" % (item.flavor, flavor))
+            LOG.debug("item.flavor: %s, flavor: %s", (item.flavor, flavor))
             if item.flavor.get('id') == flavor.id:
-                LOG.debug("flavor.disk: %s" % flavor.disk)
+                LOG.debug("flavor.disk: %s", flavor.disk)
                 return flavor.disk
 
 
@@ -960,7 +960,7 @@ class StorageSpecSortFilter(BaseFilter):
         result = items
 
         if sort_key not in self.accept_keys:
-            LOG.warning("Invalid key is specified: %s" % sort_key)
+            LOG.warning("Invalid key is specified: %s", sort_key)
             return result
 
         if sort_key == 'created_at':