From b9d97599e4e77738ad2b41960fc6d75029c4f50e Mon Sep 17 00:00:00 2001
From: Dina Belova <dbelova@mirantis.com>
Date: Tue, 29 Apr 2014 18:24:25 +0400
Subject: [PATCH] Use None instead of mutables in method params defaults

Mutables in the method params defaults might cause errors and
that's why it's anti-pattern in most of the cases and should be
removed.

Change-Id: Ifb59a16c927a4bc285f7b70fac87f719054020f4
---
 ceilometer/agent.py                           |  5 +-
 ceilometer/api/controllers/v2.py              | 52 ++++++++++++++-----
 ceilometer/compute/pollsters/util.py          |  3 +-
 ceilometer/energy/kwapi.py                    |  4 +-
 ceilometer/hardware/plugin.py                 |  3 +-
 ceilometer/image/glance.py                    |  4 +-
 ceilometer/network/floatingip.py              |  2 +-
 ceilometer/network/statistics/__init__.py     |  3 +-
 ceilometer/objectstore/swift.py               | 10 ++--
 ceilometer/pipeline.py                        |  3 +-
 ceilometer/plugin.py                          |  2 +-
 ceilometer/storage/__init__.py                |  8 +--
 ceilometer/storage/base.py                    | 12 ++---
 ceilometer/storage/impl_db2.py                |  7 ++-
 ceilometer/storage/impl_hbase.py              | 17 ++++--
 ceilometer/storage/impl_log.py                |  4 +-
 ceilometer/storage/impl_mongodb.py            | 13 +++--
 ceilometer/storage/impl_sqlalchemy.py         |  8 ++-
 ceilometer/storage/pymongo_base.py            |  4 +-
 ceilometer/tests/agentbase.py                 |  6 ++-
 ceilometer/tests/api/__init__.py              |  4 +-
 ceilometer/tests/api/v2/test_acl_scenarios.py |  4 +-
 ceilometer/tests/api/v2/test_complex_query.py |  4 +-
 ceilometer/transformer/conversions.py         |  4 +-
 24 files changed, 121 insertions(+), 65 deletions(-)

diff --git a/ceilometer/agent.py b/ceilometer/agent.py
index 789153fc20..a407a8bdff 100644
--- a/ceilometer/agent.py
+++ b/ceilometer/agent.py
@@ -99,8 +99,9 @@ class PollingTask(object):
 
 class AgentManager(os_service.Service):
 
-    def __init__(self, namespace, default_discovery=[]):
+    def __init__(self, namespace, default_discovery=None):
         super(AgentManager, self).__init__()
+        default_discovery = default_discovery or []
         self.default_discovery = default_discovery
         self.pollster_manager = self._extensions('poll', namespace)
         self.discovery_manager = self._extensions('discover')
@@ -156,7 +157,7 @@ class AgentManager(os_service.Service):
                 return d.obj
         return None
 
-    def discover(self, discovery=[]):
+    def discover(self, discovery=None):
         resources = []
         for url in (discovery or self.default_discovery):
             name, param = self._parse_discoverer(url)
diff --git a/ceilometer/api/controllers/v2.py b/ceilometer/api/controllers/v2.py
index c7bb614135..dbe870825a 100644
--- a/ceilometer/api/controllers/v2.py
+++ b/ceilometer/api/controllers/v2.py
@@ -332,7 +332,7 @@ def _verify_query_segregation(query, auth_project=None):
                 raise ProjectNotAuthorized(q.value)
 
 
-def _validate_query(query, db_func, internal_keys=[],
+def _validate_query(query, db_func, internal_keys=None,
                     allow_timestamps=True):
     """Validates the syntax of the query and verifies that the query
     request is authorized for the included project.
@@ -356,6 +356,7 @@ def _validate_query(query, db_func, internal_keys=[],
 
     """
 
+    internal_keys = internal_keys or []
     _verify_query_segregation(query)
 
     valid_keys = inspect.getargspec(db_func)[0]
@@ -446,8 +447,9 @@ def _validate_timestamp_fields(query, field_name, operator_list,
     return False
 
 
-def _query_to_kwargs(query, db_func, internal_keys=[],
+def _query_to_kwargs(query, db_func, internal_keys=None,
                      allow_timestamps=True):
+    internal_keys = internal_keys or []
     _validate_query(query, db_func, internal_keys=internal_keys,
                     allow_timestamps=allow_timestamps)
     query = _sanitize_query(query, db_func)
@@ -519,7 +521,7 @@ def _validate_groupby_fields(groupby_fields):
     return list(set(groupby_fields))
 
 
-def _get_query_timestamps(args={}):
+def _get_query_timestamps(args=None):
     """Return any optional timestamp information in the request.
 
     Determine the desired range, if any, from the GET arguments. Set
@@ -536,6 +538,12 @@ def _get_query_timestamps(args={}):
     search_offset: search_offset parameter from request
 
     """
+    if args is None:
+        return {'query_start': None,
+                'query_end': None,
+                'start_timestamp': None,
+                'end_timestamp': None,
+                'search_offset': 0}
     search_offset = int(args.get('search_offset', 0))
 
     start_timestamp = args.get('start_timestamp')
@@ -645,8 +653,9 @@ class OldSample(_Base):
     message_id = wtypes.text
     "A unique identifier for the sample"
 
-    def __init__(self, counter_volume=None, resource_metadata={},
+    def __init__(self, counter_volume=None, resource_metadata=None,
                  timestamp=None, **kwds):
+        resource_metadata = resource_metadata or {}
         if counter_volume is not None:
             counter_volume = float(counter_volume)
         resource_metadata = _flatten_metadata(resource_metadata)
@@ -810,12 +819,13 @@ class MeterController(rest.RestController):
         self.meter_name = meter_name
 
     @wsme_pecan.wsexpose([OldSample], [Query], int)
-    def get_all(self, q=[], limit=None):
+    def get_all(self, q=None, limit=None):
         """Return samples for the meter.
 
         :param q: Filter rules for the data to be returned.
         :param limit: Maximum number of samples to return.
         """
+        q = q or []
         if limit and limit < 0:
             raise ClientSideError(_("Limit must be positive"))
         kwargs = _query_to_kwargs(q, storage.SampleFilter.__init__)
@@ -886,7 +896,7 @@ class MeterController(rest.RestController):
         return samples
 
     @wsme_pecan.wsexpose([Statistics], [Query], [unicode], int, [Aggregate])
-    def statistics(self, q=[], groupby=[], period=None, aggregate=[]):
+    def statistics(self, q=None, groupby=None, period=None, aggregate=None):
         """Computes the statistics of the samples in the time range given.
 
         :param q: Filter rules for the data to be returned.
@@ -895,6 +905,10 @@ class MeterController(rest.RestController):
                        period long of that number of seconds.
         :param aggregate: The selectable aggregation functions to be applied.
         """
+        q = q or []
+        groupby = groupby or []
+        aggregate = aggregate or []
+
         if period and period < 0:
             raise ClientSideError(_("Period must be positive."))
 
@@ -979,11 +993,13 @@ class MetersController(rest.RestController):
         return MeterController(meter_name), remainder
 
     @wsme_pecan.wsexpose([Meter], [Query])
-    def get_all(self, q=[]):
+    def get_all(self, q=None):
         """Return all known meters, based on the data recorded so far.
 
         :param q: Filter rules for the meters to be returned.
         """
+        q = q or []
+
         #Timestamp field is not supported for Meter queries
         kwargs = _query_to_kwargs(q, pecan.request.storage_conn.get_meters,
                                   allow_timestamps=False)
@@ -1067,12 +1083,14 @@ class SamplesController(rest.RestController):
     """Controller managing the samples."""
 
     @wsme_pecan.wsexpose([Sample], [Query], int)
-    def get_all(self, q=[], limit=None):
+    def get_all(self, q=None, limit=None):
         """Return all known samples, based on the data recorded so far.
 
         :param q: Filter rules for the samples to be returned.
         :param limit: Maximum number of samples to be returned.
         """
+        q = q or []
+
         if limit and limit < 0:
             raise ClientSideError(_("Limit must be positive"))
         kwargs = _query_to_kwargs(q, storage.SampleFilter.__init__)
@@ -1145,8 +1163,9 @@ class ValidatedComplexQuery(object):
 
     timestamp_fields = ["timestamp", "state_timestamp"]
 
-    def __init__(self, query, db_model, additional_name_mapping={},
+    def __init__(self, query, db_model, additional_name_mapping=None,
                  metadata_allowed=False):
+        additional_name_mapping = additional_name_mapping or {}
         self.name_mapping = {"user": "user_id",
                              "project": "project_id"}
         self.name_mapping.update(additional_name_mapping)
@@ -1404,7 +1423,8 @@ class Resource(_Base):
     source = wtypes.text
     "The source where the resource come from"
 
-    def __init__(self, metadata={}, **kwds):
+    def __init__(self, metadata=None, **kwds):
+        metadata = metadata or {}
         metadata = _flatten_metadata(metadata)
         super(Resource, self).__init__(metadata=metadata, **kwds)
 
@@ -1457,12 +1477,13 @@ class ResourcesController(rest.RestController):
                                           self._resource_links(resource_id))
 
     @wsme_pecan.wsexpose([Resource], [Query], int)
-    def get_all(self, q=[], meter_links=1):
+    def get_all(self, q=None, meter_links=1):
         """Retrieve definitions of all of the resources.
 
         :param q: Filter rules for the resources to be returned.
         :param meter_links: option to include related meter links
         """
+        q = q or []
         kwargs = _query_to_kwargs(q, pecan.request.storage_conn.get_resources)
         resources = [
             Resource.from_db_and_links(r,
@@ -1974,11 +1995,12 @@ class AlarmController(rest.RestController):
     # TODO(eglynn): add pagination marker to signature once overall
     #               API support for pagination is finalized
     @wsme_pecan.wsexpose([AlarmChange], [Query])
-    def history(self, q=[]):
+    def history(self, q=None):
         """Assembles the alarm history requested.
 
         :param q: Filter rules for the changes to be described.
         """
+        q = q or []
         # allow history to be returned for deleted alarms, but scope changes
         # returned to those carried out on behalf of the auth'd tenant, to
         # avoid inappropriate cross-tenant visibility of alarm history
@@ -2105,11 +2127,12 @@ class AlarmsController(rest.RestController):
         return Alarm.from_db_model(alarm)
 
     @wsme_pecan.wsexpose([Alarm], [Query])
-    def get_all(self, q=[]):
+    def get_all(self, q=None):
         """Return all alarms, based on the query provided.
 
         :param q: Filter rules for the alarms to be returned.
         """
+        q = q or []
         #Timestamp is not supported field for Simple Alarm queries
         kwargs = _query_to_kwargs(q,
                                   pecan.request.storage_conn.get_alarms,
@@ -2310,11 +2333,12 @@ class EventsController(rest.RestController):
 
     @requires_admin
     @wsme_pecan.wsexpose([Event], [EventQuery])
-    def get_all(self, q=[]):
+    def get_all(self, q=None):
         """Return all events matching the query filters.
 
         :param q: Filter arguments for which Events to return
         """
+        q = q or []
         event_filter = _event_query_to_event_filter(q)
         return [Event(message_id=event.message_id,
                       event_type=event.event_type,
diff --git a/ceilometer/compute/pollsters/util.py b/ceilometer/compute/pollsters/util.py
index a8aea437be..ed60bf6656 100644
--- a/ceilometer/compute/pollsters/util.py
+++ b/ceilometer/compute/pollsters/util.py
@@ -77,7 +77,8 @@ def _get_metadata_from_object(instance):
 
 
 def make_sample_from_instance(instance, name, type, unit, volume,
-                              additional_metadata={}):
+                              additional_metadata=None):
+    additional_metadata = additional_metadata or {}
     resource_metadata = _get_metadata_from_object(instance)
     resource_metadata.update(additional_metadata)
     return sample.Sample(
diff --git a/ceilometer/energy/kwapi.py b/ceilometer/energy/kwapi.py
index 9a9479e7b5..069ccc718d 100644
--- a/ceilometer/energy/kwapi.py
+++ b/ceilometer/energy/kwapi.py
@@ -82,7 +82,7 @@ class _Base(plugin.CentralPollster):
 class EnergyPollster(_Base):
     """Measures energy consumption."""
 
-    def get_samples(self, manager, cache, resources=[]):
+    def get_samples(self, manager, cache, resources=None):
         """Returns all samples."""
         for probe in self._iter_probes(manager.keystone, cache):
             yield sample.Sample(
@@ -102,7 +102,7 @@ class EnergyPollster(_Base):
 class PowerPollster(_Base):
     """Measures power consumption."""
 
-    def get_samples(self, manager, cache, resources=[]):
+    def get_samples(self, manager, cache, resources=None):
         """Returns all samples."""
         for probe in self._iter_probes(manager.keystone, cache):
             yield sample.Sample(
diff --git a/ceilometer/hardware/plugin.py b/ceilometer/hardware/plugin.py
index 243cf4d358..b62e53b1d0 100644
--- a/ceilometer/hardware/plugin.py
+++ b/ceilometer/hardware/plugin.py
@@ -44,13 +44,14 @@ class HardwarePollster(plugin.CentralPollster):
         super(HardwarePollster, self).__init__()
         self.inspectors = {}
 
-    def get_samples(self, manager, cache, resources=[]):
+    def get_samples(self, manager, cache, resources=None):
         """Return an iterable of Sample instances from polling the resources.
 
         :param manager: The service manager invoking the plugin
         :param cache: A dictionary for passing data between plugins
         :param resources: end point to poll data from
         """
+        resources = resources or []
         h_cache = cache.setdefault(self.CACHE_KEY, {})
         sample_iters = []
         for res in resources:
diff --git a/ceilometer/image/glance.py b/ceilometer/image/glance.py
index 54c263d666..20c3b9a986 100644
--- a/ceilometer/image/glance.py
+++ b/ceilometer/image/glance.py
@@ -104,7 +104,7 @@ class _Base(plugin.PollsterBase):
 
 class ImagePollster(_Base):
 
-    def get_samples(self, manager, cache, resources=[]):
+    def get_samples(self, manager, cache, resources=None):
         for image in self._iter_images(manager.keystone, cache):
             yield sample.Sample(
                 name='image',
@@ -121,7 +121,7 @@ class ImagePollster(_Base):
 
 class ImageSizePollster(_Base):
 
-    def get_samples(self, manager, cache, resources=[]):
+    def get_samples(self, manager, cache, resources=None):
         for image in self._iter_images(manager.keystone, cache):
             yield sample.Sample(
                 name='image.size',
diff --git a/ceilometer/network/floatingip.py b/ceilometer/network/floatingip.py
index d8e429e627..64ebd44f31 100644
--- a/ceilometer/network/floatingip.py
+++ b/ceilometer/network/floatingip.py
@@ -40,7 +40,7 @@ class FloatingIPPollster(plugin.CentralPollster):
             cache['floating_ips'] = list(self._get_floating_ips())
         return iter(cache['floating_ips'])
 
-    def get_samples(self, manager, cache, resources=[]):
+    def get_samples(self, manager, cache, resources=None):
         for ip in self._iter_floating_ips(cache):
             self.LOG.info(_("FLOATING IP USAGE: %s") % ip.ip)
             # FIXME (flwang) Now Nova API /os-floating-ips can't provide those
diff --git a/ceilometer/network/statistics/__init__.py b/ceilometer/network/statistics/__init__.py
index 29df6e9931..3b8dc2bb5a 100644
--- a/ceilometer/network/statistics/__init__.py
+++ b/ceilometer/network/statistics/__init__.py
@@ -63,7 +63,8 @@ class _Base(plugin.CentralPollster):
                                                           scheme).driver()
         return _Base.drivers[scheme]
 
-    def get_samples(self, manager, cache, resources=[]):
+    def get_samples(self, manager, cache, resources=None):
+        resources = resources or []
         for resource in resources:
             parse_url, params = self._parse_my_resource(resource)
             ext = self.get_driver(parse_url.scheme)
diff --git a/ceilometer/objectstore/swift.py b/ceilometer/objectstore/swift.py
index abfc75c385..99a2b19363 100644
--- a/ceilometer/objectstore/swift.py
+++ b/ceilometer/objectstore/swift.py
@@ -88,7 +88,7 @@ class ObjectsPollster(_Base):
     """Iterate over all accounts, using keystone.
     """
 
-    def get_samples(self, manager, cache, resources=[]):
+    def get_samples(self, manager, cache, resources=None):
         for tenant, account in self._iter_accounts(manager.keystone, cache):
             yield sample.Sample(
                 name='storage.objects',
@@ -107,7 +107,7 @@ class ObjectsSizePollster(_Base):
     """Iterate over all accounts, using keystone.
     """
 
-    def get_samples(self, manager, cache, resources=[]):
+    def get_samples(self, manager, cache, resources=None):
         for tenant, account in self._iter_accounts(manager.keystone, cache):
             yield sample.Sample(
                 name='storage.objects.size',
@@ -126,7 +126,7 @@ class ObjectsContainersPollster(_Base):
     """Iterate over all accounts, using keystone.
     """
 
-    def get_samples(self, manager, cache, resources=[]):
+    def get_samples(self, manager, cache, resources=None):
         for tenant, account in self._iter_accounts(manager.keystone, cache):
             yield sample.Sample(
                 name='storage.objects.containers',
@@ -147,7 +147,7 @@ class ContainersObjectsPollster(_Base):
 
     METHOD = 'get'
 
-    def get_samples(self, manager, cache, resources=[]):
+    def get_samples(self, manager, cache, resources=None):
         for project, account in self._iter_accounts(manager.keystone, cache):
             containers_info = account[1]
             for container in containers_info:
@@ -170,7 +170,7 @@ class ContainersSizePollster(_Base):
 
     METHOD = 'get'
 
-    def get_samples(self, manager, cache, resources=[]):
+    def get_samples(self, manager, cache, resources=None):
         for project, account in self._iter_accounts(manager.keystone, cache):
             containers_info = account[1]
             for container in containers_info:
diff --git a/ceilometer/pipeline.py b/ceilometer/pipeline.py
index 2b1c265011..f7d2828fc8 100644
--- a/ceilometer/pipeline.py
+++ b/ceilometer/pipeline.py
@@ -55,7 +55,8 @@ class PipelineException(Exception):
 
 class PublishContext(object):
 
-    def __init__(self, context, pipelines=[]):
+    def __init__(self, context, pipelines=None):
+        pipelines = pipelines or []
         self.pipelines = set(pipelines)
         self.context = context
 
diff --git a/ceilometer/plugin.py b/ceilometer/plugin.py
index 7c443abe37..7e7e4db4b7 100644
--- a/ceilometer/plugin.py
+++ b/ceilometer/plugin.py
@@ -130,7 +130,7 @@ class PollsterBase(PluginBase):
     """Base class for plugins that support the polling API."""
 
     @abc.abstractmethod
-    def get_samples(self, manager, cache, resources=[]):
+    def get_samples(self, manager, cache, resources=None):
         """Return a sequence of Counter instances from polling the resources.
 
         :param manager: The service manager class invoking the plugin.
diff --git a/ceilometer/storage/__init__.py b/ceilometer/storage/__init__.py
index 1aa1e0ef7c..eefa5985bb 100644
--- a/ceilometer/storage/__init__.py
+++ b/ceilometer/storage/__init__.py
@@ -104,7 +104,7 @@ class SampleFilter(object):
                  end=None, end_timestamp_op=None,
                  resource=None, meter=None,
                  source=None, message_id=None,
-                 metaquery={}):
+                 metaquery=None):
         self.user = user
         self.project = project
         self.start = utils.sanitize_timestamp(start)
@@ -114,7 +114,7 @@ class SampleFilter(object):
         self.resource = resource
         self.meter = meter
         self.source = source
-        self.metaquery = metaquery
+        self.metaquery = metaquery or {}
         self.message_id = message_id
 
 
@@ -137,12 +137,12 @@ class EventFilter(object):
     """
 
     def __init__(self, start_time=None, end_time=None, event_type=None,
-                 message_id=None, traits_filter=[]):
+                 message_id=None, traits_filter=None):
         self.start_time = utils.sanitize_timestamp(start_time)
         self.end_time = utils.sanitize_timestamp(end_time)
         self.message_id = message_id
         self.event_type = event_type
-        self.traits_filter = traits_filter
+        self.traits_filter = traits_filter or []
 
     def __repr__(self):
         return ("<EventFilter(start_time: %s,"
diff --git a/ceilometer/storage/base.py b/ceilometer/storage/base.py
index 066d279da6..173f58d84d 100644
--- a/ceilometer/storage/base.py
+++ b/ceilometer/storage/base.py
@@ -83,8 +83,8 @@ class NoResultFound(Exception):
 class Pagination(object):
     """Class for pagination query."""
 
-    def __init__(self, limit=None, primary_sort_dir='desc', sort_keys=[],
-                 sort_dirs=[], marker_value=None):
+    def __init__(self, limit=None, primary_sort_dir='desc', sort_keys=None,
+                 sort_dirs=None, marker_value=None):
         """This puts all parameters used for paginate query together.
 
         :param limit: Maximum number of items to return;
@@ -99,8 +99,8 @@ class Pagination(object):
         self.limit = limit
         self.primary_sort_dir = primary_sort_dir
         self.marker_value = marker_value
-        self.sort_keys = sort_keys
-        self.sort_dirs = sort_dirs
+        self.sort_keys = sort_keys or []
+        self.sort_dirs = sort_dirs or []
 
 
 class Connection(object):
@@ -177,7 +177,7 @@ class Connection(object):
     def get_resources(user=None, project=None, source=None,
                       start_timestamp=None, start_timestamp_op=None,
                       end_timestamp=None, end_timestamp_op=None,
-                      metaquery={}, resource=None, pagination=None):
+                      metaquery=None, resource=None, pagination=None):
         """Return an iterable of models.Resource instances containing
         resource information.
 
@@ -196,7 +196,7 @@ class Connection(object):
 
     @staticmethod
     def get_meters(user=None, project=None, resource=None, source=None,
-                   metaquery={}, pagination=None):
+                   metaquery=None, pagination=None):
         """Return an iterable of model.Meter instances containing meter
         information.
 
diff --git a/ceilometer/storage/impl_db2.py b/ceilometer/storage/impl_db2.py
index 90ff9012c3..26a2cdd259 100644
--- a/ceilometer/storage/impl_db2.py
+++ b/ceilometer/storage/impl_db2.py
@@ -127,7 +127,7 @@ class Connection(pymongo_base.Connection):
         self.upgrade()
 
     @classmethod
-    def _build_sort_instructions(cls, sort_keys=[], sort_dir='desc'):
+    def _build_sort_instructions(cls, sort_keys=None, sort_dir='desc'):
         """Returns a sort_instruction.
 
         Sort instructions are used in the query to determine what attributes
@@ -137,6 +137,7 @@ class Connection(pymongo_base.Connection):
         :param sort_dir: direction in which results be sorted (asc, desc).
         :return: sort parameters
         """
+        sort_keys = sort_keys or []
         sort_instructions = []
         _sort_dir = cls.SORT_OPERATION_MAP.get(
             sort_dir, cls.SORT_OPERATION_MAP['desc'])
@@ -235,7 +236,7 @@ class Connection(pymongo_base.Connection):
     def get_resources(self, user=None, project=None, source=None,
                       start_timestamp=None, start_timestamp_op=None,
                       end_timestamp=None, end_timestamp_op=None,
-                      metaquery={}, resource=None, pagination=None):
+                      metaquery=None, resource=None, pagination=None):
         """Return an iterable of models.Resource instances
 
         :param user: Optional ID for user that owns the resource.
@@ -252,6 +253,8 @@ class Connection(pymongo_base.Connection):
         if pagination:
             raise NotImplementedError('Pagination not implemented')
 
+        metaquery = metaquery or {}
+
         q = {}
         if user is not None:
             q['user_id'] = user
diff --git a/ceilometer/storage/impl_hbase.py b/ceilometer/storage/impl_hbase.py
index 0dd081a6df..4bcdecc70c 100644
--- a/ceilometer/storage/impl_hbase.py
+++ b/ceilometer/storage/impl_hbase.py
@@ -310,7 +310,7 @@ class Connection(base.Connection):
     def get_resources(self, user=None, project=None, source=None,
                       start_timestamp=None, start_timestamp_op=None,
                       end_timestamp=None, end_timestamp_op=None,
-                      metaquery={}, resource=None, pagination=None):
+                      metaquery=None, resource=None, pagination=None):
         """Return an iterable of models.Resource instances
 
         :param user: Optional ID for user that owns the resource.
@@ -327,6 +327,8 @@ class Connection(base.Connection):
         if pagination:
             raise NotImplementedError('Pagination not implemented')
 
+        metaquery = metaquery or {}
+
         sample_filter = storage.SampleFilter(
             user=user, project=project,
             start=start_timestamp, start_timestamp_op=start_timestamp_op,
@@ -368,7 +370,7 @@ class Connection(base.Connection):
                 )
 
     def get_meters(self, user=None, project=None, resource=None, source=None,
-                   metaquery={}, pagination=None):
+                   metaquery=None, pagination=None):
         """Return an iterable of models.Meter instances
 
         :param user: Optional ID for user that owns the resource.
@@ -379,6 +381,8 @@ class Connection(base.Connection):
         :param pagination: Optional pagination query.
         """
 
+        metaquery = metaquery or {}
+
         if pagination:
             raise NotImplementedError(_('Pagination not implemented'))
         with self.conn_pool.connection() as conn:
@@ -568,7 +572,8 @@ class MTable(object):
     def delete(self, key):
         del self._rows[key]
 
-    def scan(self, filter=None, columns=[], row_start=None, row_stop=None):
+    def scan(self, filter=None, columns=None, row_start=None, row_stop=None):
+        columns = columns or []
         sorted_keys = sorted(self._rows)
         # copy data between row_start and row_stop into a dict
         rows = {}
@@ -661,7 +666,8 @@ class MConnection(object):
     def open(self):
         LOG.debug(_("Opening in-memory HBase connection"))
 
-    def create_table(self, n, families={}):
+    def create_table(self, n, families=None):
+        families = families or {}
         if n in self.tables:
             return self.tables[n]
         t = MTable(n, families)
@@ -879,12 +885,13 @@ def deserialize_entry(entry, get_raw_meta=True):
     return flatten_result, sources, meters, metadata
 
 
-def serialize_entry(data={}, **kwargs):
+def serialize_entry(data=None, **kwargs):
     """Return a dict that is ready to be stored to HBase
 
     :param data: dict to be serialized
     :param kwargs: additional args
     """
+    data = data or {}
     entry_dict = copy.copy(data)
     entry_dict.update(**kwargs)
 
diff --git a/ceilometer/storage/impl_log.py b/ceilometer/storage/impl_log.py
index 4ab2a7793b..bce6231690 100644
--- a/ceilometer/storage/impl_log.py
+++ b/ceilometer/storage/impl_log.py
@@ -59,7 +59,7 @@ class Connection(base.Connection):
     def get_resources(self, user=None, project=None, source=None,
                       start_timestamp=None, start_timestamp_op=None,
                       end_timestamp=None, end_timestamp_op=None,
-                      metaquery={}, resource=None, pagination=None):
+                      metaquery=None, resource=None, pagination=None):
         """Return an iterable of dictionaries containing resource information.
 
         { 'resource_id': UUID of the resource,
@@ -84,7 +84,7 @@ class Connection(base.Connection):
         return []
 
     def get_meters(self, user=None, project=None, resource=None, source=None,
-                   limit=None, metaquery={}, pagination=None):
+                   limit=None, metaquery=None, pagination=None):
         """Return an iterable of dictionaries containing meter information.
 
         { 'name': name of the meter,
diff --git a/ceilometer/storage/impl_mongodb.py b/ceilometer/storage/impl_mongodb.py
index f3b670f949..13e7eec3d4 100644
--- a/ceilometer/storage/impl_mongodb.py
+++ b/ceilometer/storage/impl_mongodb.py
@@ -586,7 +586,7 @@ class Connection(pymongo_base.Connection):
         return dict(criteria_equ, ** criteria_cmp)
 
     @classmethod
-    def _build_paginate_query(cls, marker, sort_keys=[], sort_dir='desc'):
+    def _build_paginate_query(cls, marker, sort_keys=None, sort_dir='desc'):
         """Returns a query with sorting / pagination.
 
         Pagination works by requiring sort_key and sort_dir.
@@ -600,6 +600,7 @@ class Connection(pymongo_base.Connection):
         :return: sort parameters, query to use
         """
         all_sort = []
+        sort_keys = sort_keys or []
         all_sort, _op = cls._build_sort_instructions(sort_keys, sort_dir)
 
         if marker is not None:
@@ -625,7 +626,7 @@ class Connection(pymongo_base.Connection):
         return all_sort, metaquery
 
     @classmethod
-    def _build_sort_instructions(cls, sort_keys=[], sort_dir='desc'):
+    def _build_sort_instructions(cls, sort_keys=None, sort_dir='desc'):
         """Returns a sort_instruction and paging operator.
 
         Sort instructions are used in the query to determine what attributes
@@ -635,6 +636,7 @@ class Connection(pymongo_base.Connection):
         :param sort_dir: direction in which results be sorted (asc, desc).
         :return: sort instructions and paging operator
         """
+        sort_keys = sort_keys or []
         sort_instructions = []
         _sort_dir, operation = cls.SORT_OPERATION_MAPPING.get(
             sort_dir, cls.SORT_OPERATION_MAPPING['desc'])
@@ -647,7 +649,7 @@ class Connection(pymongo_base.Connection):
 
     @classmethod
     def paginate_query(cls, q, db_collection, limit=None, marker=None,
-                       sort_keys=[], sort_dir='desc'):
+                       sort_keys=None, sort_dir='desc'):
         """Returns a query result with sorting / pagination.
 
         Pagination works by requiring sort_key and sort_dir.
@@ -663,6 +665,7 @@ class Connection(pymongo_base.Connection):
         return: The query with sorting/pagination added.
         """
 
+        sort_keys = sort_keys or []
         all_sort, query = cls._build_paginate_query(marker,
                                                     sort_keys,
                                                     sort_dir)
@@ -772,7 +775,7 @@ class Connection(pymongo_base.Connection):
     def get_resources(self, user=None, project=None, source=None,
                       start_timestamp=None, start_timestamp_op=None,
                       end_timestamp=None, end_timestamp_op=None,
-                      metaquery={}, resource=None, pagination=None):
+                      metaquery=None, resource=None, pagination=None):
         """Return an iterable of models.Resource instances
 
         :param user: Optional ID for user that owns the resource.
@@ -789,6 +792,8 @@ class Connection(pymongo_base.Connection):
         if pagination:
             raise NotImplementedError('Pagination not implemented')
 
+        metaquery = metaquery or {}
+
         query = {}
         if user is not None:
             query['user_id'] = user
diff --git a/ceilometer/storage/impl_sqlalchemy.py b/ceilometer/storage/impl_sqlalchemy.py
index 67f86e8092..a8e5e4f852 100644
--- a/ceilometer/storage/impl_sqlalchemy.py
+++ b/ceilometer/storage/impl_sqlalchemy.py
@@ -360,7 +360,7 @@ class Connection(base.Connection):
     def get_resources(self, user=None, project=None, source=None,
                       start_timestamp=None, start_timestamp_op=None,
                       end_timestamp=None, end_timestamp_op=None,
-                      metaquery={}, resource=None, pagination=None):
+                      metaquery=None, resource=None, pagination=None):
         """Return an iterable of api_models.Resource instances
 
         :param user: Optional ID for user that owns the resource.
@@ -377,6 +377,8 @@ class Connection(base.Connection):
         if pagination:
             raise NotImplementedError('Pagination not implemented')
 
+        metaquery = metaquery or {}
+
         def _apply_filters(query):
             # TODO(gordc) this should be merged with make_query_from_filter
             for column, value in [(models.Sample.resource_id, resource),
@@ -437,7 +439,7 @@ class Connection(base.Connection):
                 )
 
     def get_meters(self, user=None, project=None, resource=None, source=None,
-                   metaquery={}, pagination=None):
+                   metaquery=None, pagination=None):
         """Return an iterable of api_models.Meter instances
 
         :param user: Optional ID for user that owns the resource.
@@ -451,6 +453,8 @@ class Connection(base.Connection):
         if pagination:
             raise NotImplementedError('Pagination not implemented')
 
+        metaquery = metaquery or {}
+
         def _apply_filters(query):
             # TODO(gordc) this should be merged with make_query_from_filter
             for column, value in [(models.Sample.resource_id, resource),
diff --git a/ceilometer/storage/pymongo_base.py b/ceilometer/storage/pymongo_base.py
index ed8fe9c78d..9daea1c02c 100644
--- a/ceilometer/storage/pymongo_base.py
+++ b/ceilometer/storage/pymongo_base.py
@@ -147,7 +147,7 @@ class Connection(base.Connection):
                                        COMMON_AVAILABLE_CAPABILITIES)
 
     def get_meters(self, user=None, project=None, resource=None, source=None,
-                   metaquery={}, pagination=None):
+                   metaquery=None, pagination=None):
         """Return an iterable of models.Meter instances
 
         :param user: Optional ID for user that owns the resource.
@@ -161,6 +161,8 @@ class Connection(base.Connection):
         if pagination:
             raise NotImplementedError('Pagination not implemented')
 
+        metaquery = metaquery or {}
+
         q = {}
         if user is not None:
             q['user_id'] = user
diff --git a/ceilometer/tests/agentbase.py b/ceilometer/tests/agentbase.py
index 4784037ae1..3af2d8897f 100644
--- a/ceilometer/tests/agentbase.py
+++ b/ceilometer/tests/agentbase.py
@@ -72,7 +72,8 @@ default_test_data = TestSample(
 class TestPollster(plugin.PollsterBase):
     test_data = default_test_data
 
-    def get_samples(self, manager, cache, resources=[]):
+    def get_samples(self, manager, cache, resources=None):
+        resources = resources or []
         self.samples.append((manager, resources))
         self.resources.extend(resources)
         c = copy.copy(self.test_data)
@@ -81,7 +82,8 @@ class TestPollster(plugin.PollsterBase):
 
 
 class TestPollsterException(TestPollster):
-    def get_samples(self, manager, cache, resources=[]):
+    def get_samples(self, manager, cache, resources=None):
+        resources = resources or []
         self.samples.append((manager, resources))
         self.resources.extend(resources)
         raise Exception()
diff --git a/ceilometer/tests/api/__init__.py b/ceilometer/tests/api/__init__.py
index 69fbb2b99f..e8cdf70bdf 100644
--- a/ceilometer/tests/api/__init__.py
+++ b/ceilometer/tests/api/__init__.py
@@ -138,7 +138,7 @@ class FunctionalTest(db_test_base.TestBase):
         return response
 
     def get_json(self, path, expect_errors=False, headers=None,
-                 extra_environ=None, q=[], groupby=[], status=None,
+                 extra_environ=None, q=None, groupby=None, status=None,
                  override_params=None, **params):
         """Sends simulated HTTP GET request to Pecan test app.
 
@@ -155,6 +155,8 @@ class FunctionalTest(db_test_base.TestBase):
         :param override_params: literally encoded query param string
         :param params: content for wsgi.input of request
         """
+        q = q or []
+        groupby = groupby or []
         full_path = self.PATH_PREFIX + path
         if override_params:
             all_params = override_params
diff --git a/ceilometer/tests/api/v2/test_acl_scenarios.py b/ceilometer/tests/api/v2/test_acl_scenarios.py
index 0cd27b3ed0..f0fd53c8aa 100644
--- a/ceilometer/tests/api/v2/test_acl_scenarios.py
+++ b/ceilometer/tests/api/v2/test_acl_scenarios.py
@@ -108,11 +108,11 @@ class TestAPIACL(FunctionalTest,
             self.conn.record_metering_data(msg)
 
     def get_json(self, path, expect_errors=False, headers=None,
-                 q=[], **params):
+                 q=None, **params):
         return super(TestAPIACL, self).get_json(path,
                                                 expect_errors=expect_errors,
                                                 headers=headers,
-                                                q=q,
+                                                q=q or [],
                                                 extra_environ=self.environ,
                                                 **params)
 
diff --git a/ceilometer/tests/api/v2/test_complex_query.py b/ceilometer/tests/api/v2/test_complex_query.py
index c7009c486d..af78178d60 100644
--- a/ceilometer/tests/api/v2/test_complex_query.py
+++ b/ceilometer/tests/api/v2/test_complex_query.py
@@ -29,11 +29,11 @@ from ceilometer import storage as storage
 
 
 class FakeComplexQuery(api.ValidatedComplexQuery):
-    def __init__(self, db_model, additional_name_mapping={}, metadata=False):
+    def __init__(self, db_model, additional_name_mapping=None, metadata=False):
         super(FakeComplexQuery, self).__init__(query=None,
                                                db_model=db_model,
                                                additional_name_mapping=
-                                               additional_name_mapping,
+                                               additional_name_mapping or {},
                                                metadata_allowed=metadata)
 
 
diff --git a/ceilometer/transformer/conversions.py b/ceilometer/transformer/conversions.py
index 8514099601..44f563b642 100644
--- a/ceilometer/transformer/conversions.py
+++ b/ceilometer/transformer/conversions.py
@@ -55,7 +55,7 @@ class ScalingTransformer(transformer.TransformerBase):
     """Transformer to apply a scaling conversion.
     """
 
-    def __init__(self, source={}, target={}, **kwargs):
+    def __init__(self, source=None, target=None, **kwargs):
         """Initialize transformer with configured parameters.
 
         :param source: dict containing source sample unit
@@ -63,6 +63,8 @@ class ScalingTransformer(transformer.TransformerBase):
                        unit and scaling factor (a missing value
                        connotes no change)
         """
+        source = source or {}
+        target = target or {}
         self.source = source
         self.target = target
         self.scale = target.get('scale')