diff --git a/HACKING.rst b/HACKING.rst
index 8652971..025bf74 100644
--- a/HACKING.rst
+++ b/HACKING.rst
@@ -12,6 +12,7 @@
 - [T104] Scenario tests require a services decorator
 - [T105] Unit tests cannot use setUpClass
 - [T106] vim configuration should not be kept in source files.
+- [N322] Method's default argument shouldn't be mutable
 
 Test Data/Configuration
 -----------------------
diff --git a/tempest/api/compute/base.py b/tempest/api/compute/base.py
index 343a39a..47d1254 100644
--- a/tempest/api/compute/base.py
+++ b/tempest/api/compute/base.py
@@ -271,10 +271,10 @@
         return resp, body
 
     @classmethod
-    def create_test_server_group(cls, name="", policy=[]):
+    def create_test_server_group(cls, name="", policy=None):
         if not name:
             name = data_utils.rand_name(cls.__name__ + "-Server-Group")
-        if not policy:
+        if policy is None:
             policy = ['affinity']
         resp, body = cls.servers_client.create_server_group(name, policy)
         cls.server_groups.append(body['id'])
diff --git a/tempest/api/compute/servers/test_servers_negative.py b/tempest/api/compute/servers/test_servers_negative.py
index 792b523..b9ec29e 100644
--- a/tempest/api/compute/servers/test_servers_negative.py
+++ b/tempest/api/compute/servers/test_servers_negative.py
@@ -404,13 +404,6 @@
                           nonexistent_server)
 
     @test.attr(type=['negative', 'gate'])
-    def test_force_delete_server_invalid_state(self):
-        # we can only force-delete a server in 'soft-delete' state
-        self.assertRaises(exceptions.Conflict,
-                          self.client.force_delete_server,
-                          self.server_id)
-
-    @test.attr(type=['negative', 'gate'])
     def test_restore_nonexistent_server_id(self):
         # restore-delete a non existent server
         nonexistent_server = data_utils.rand_uuid()
diff --git a/tempest/api/orchestration/base.py b/tempest/api/orchestration/base.py
index d0fb825..0b22de5 100644
--- a/tempest/api/orchestration/base.py
+++ b/tempest/api/orchestration/base.py
@@ -64,8 +64,10 @@
         return admin_client
 
     @classmethod
-    def create_stack(cls, stack_name, template_data, parameters={},
+    def create_stack(cls, stack_name, template_data, parameters=None,
                      environment=None, files=None):
+        if parameters is None:
+            parameters = {}
         resp, body = cls.client.create_stack(
             stack_name,
             template=template_data,
diff --git a/tempest/cmd/javelin.py b/tempest/cmd/javelin.py
index 6761a69..f37bfdb 100755
--- a/tempest/cmd/javelin.py
+++ b/tempest/cmd/javelin.py
@@ -20,6 +20,7 @@
 """
 
 import argparse
+import datetime
 import logging
 import os
 import sys
@@ -30,12 +31,14 @@
 import tempest.auth
 from tempest import config
 from tempest import exceptions
+from tempest.openstack.common import timeutils
 from tempest.services.compute.json import flavors_client
 from tempest.services.compute.json import servers_client
 from tempest.services.identity.json import identity_client
 from tempest.services.image.v2.json import image_client
 from tempest.services.object_storage import container_client
 from tempest.services.object_storage import object_client
+from tempest.services.telemetry.json import telemetry_client
 from tempest.services.volume.json import volumes_client
 
 OPTS = {}
@@ -44,6 +47,8 @@
 
 LOG = None
 
+JAVELIN_START = datetime.datetime.utcnow()
+
 
 class OSClient(object):
     _creds = None
@@ -62,6 +67,7 @@
         self.containers = container_client.ContainerClient(_auth)
         self.images = image_client.ImageClientV2JSON(_auth)
         self.flavors = flavors_client.FlavorsClientJSON(_auth)
+        self.telemetry = telemetry_client.TelemetryClientJSON(_auth)
         self.volumes = volumes_client.VolumesClientJSON(_auth)
 
 
@@ -196,6 +202,7 @@
         # TODO(sdague): Volumes not yet working, bring it back once the
         # code is self testing.
         # self.check_volumes()
+        self.check_telemetry()
 
     def check_users(self):
         """Check that the users we expect to exist, do.
@@ -252,6 +259,26 @@
                                 "Server %s is not pingable at %s" % (
                                     server['name'], addr))
 
+    def check_telemetry(self):
+        """Check that ceilometer provides a sane sample.
+
+        Confirm that there are more than one sample and that they have the
+        expected metadata.
+
+        If in check mode confirm that the oldest sample available is from
+        before the upgrade.
+        """
+        LOG.info("checking telemetry")
+        for server in self.res['servers']:
+            client = client_for_user(server['owner'])
+            response, body = client.telemetry.list_samples(
+                'instance',
+                query=('metadata.display_name', 'eq', server['name'])
+            )
+            self.assertEqual(response.status, 200)
+            self.assertTrue(len(body) >= 1, 'expecting at least one sample')
+            self._confirm_telemetry_sample(server, body[-1])
+
     def check_volumes(self):
         """Check that the volumes are still there and attached."""
         if not self.res.get('volumes'):
@@ -270,6 +297,26 @@
             self.assertEqual(volume['id'], attachment['volume_id'])
             self.assertEqual(server_id, attachment['server_id'])
 
+    def _confirm_telemetry_sample(self, server, sample):
+        """Check this sample matches the expected resource metadata."""
+        # Confirm display_name
+        self.assertEqual(server['name'],
+                         sample['resource_metadata']['display_name'])
+        # Confirm instance_type of flavor
+        flavor = sample['resource_metadata'].get(
+            'flavor.name',
+            sample['resource_metadata'].get('instance_type')
+        )
+        self.assertEqual(server['flavor'], flavor)
+        # Confirm the oldest sample was created before upgrade.
+        if OPTS.mode == 'check':
+            oldest_timestamp = timeutils.normalize_time(
+                timeutils.parse_isotime(sample['timestamp']))
+            self.assertTrue(
+                oldest_timestamp < JAVELIN_START,
+                'timestamp should come before start of second javelin run'
+            )
+
 
 #######################
 #
diff --git a/tempest/common/rest_client.py b/tempest/common/rest_client.py
index ff92b67..132d0a6 100644
--- a/tempest/common/rest_client.py
+++ b/tempest/common/rest_client.py
@@ -248,8 +248,10 @@
                 return resp[i]
         return ""
 
-    def _log_request_start(self, method, req_url, req_headers={},
+    def _log_request_start(self, method, req_url, req_headers=None,
                            req_body=None):
+        if req_headers is None:
+            req_headers = {}
         caller_name = misc_utils.find_test_caller()
         trace_regex = CONF.debug.trace_requests
         if trace_regex and re.search(trace_regex, caller_name):
@@ -257,8 +259,10 @@
                            (caller_name, method, req_url))
 
     def _log_request(self, method, req_url, resp,
-                     secs="", req_headers={},
+                     secs="", req_headers=None,
                      req_body=None, resp_body=None):
+        if req_headers is None:
+            req_headers = {}
         # if we have the request id, put it in the right part of the log
         extra = dict(request_id=self._get_request_id(resp))
         # NOTE(sdague): while we still have 6 callers to this function
diff --git a/tempest/hacking/checks.py b/tempest/hacking/checks.py
index cef010e..abc60cb 100644
--- a/tempest/hacking/checks.py
+++ b/tempest/hacking/checks.py
@@ -27,6 +27,7 @@
 SETUPCLASS_DEFINITION = re.compile(r'^\s*def setUpClass')
 SCENARIO_DECORATOR = re.compile(r'\s*@.*services\((.*)\)')
 VI_HEADER_RE = re.compile(r"^#\s+vim?:.+")
+mutable_default_args = re.compile(r"^\s*def .+\((.+=\{\}|.+=\[\])")
 
 
 def import_no_clients_in_api(physical_line, filename):
@@ -119,6 +120,16 @@
                     'tests')
 
 
+def no_mutable_default_args(logical_line):
+    """Check that mutable object isn't used as default argument
+
+    N322: Method's default argument shouldn't be mutable
+    """
+    msg = "N322: Method's default argument shouldn't be mutable!"
+    if mutable_default_args.match(logical_line):
+        yield (0, msg)
+
+
 def factory(register):
     register(import_no_clients_in_api)
     register(scenario_tests_need_service_tags)
@@ -126,3 +137,4 @@
     register(no_vi_headers)
     register(service_tags_not_in_module_path)
     register(no_official_client_manager_in_api_tests)
+    register(no_mutable_default_args)
diff --git a/tempest/scenario/manager.py b/tempest/scenario/manager.py
index 7a80a66..18dc320 100644
--- a/tempest/scenario/manager.py
+++ b/tempest/scenario/manager.py
@@ -141,8 +141,8 @@
             pass
 
     def addCleanup_with_wait(self, waiter_callable, thing_id, thing_id_param,
-                             cleanup_callable, cleanup_args=[],
-                             cleanup_kwargs={}, ignore_error=True):
+                             cleanup_callable, cleanup_args=None,
+                             cleanup_kwargs=None, ignore_error=True):
         """Adds wait for ansyc resource deletion at the end of cleanups
 
         @param waiter_callable: callable to wait for the resource to delete
@@ -152,6 +152,10 @@
             the following *cleanup_args, **cleanup_kwargs.
             usually a delete method.
         """
+        if cleanup_args is None:
+            cleanup_args = []
+        if cleanup_kwargs is None:
+            cleanup_kwargs = {}
         self.addCleanup(cleanup_callable, *cleanup_args, **cleanup_kwargs)
         wait_dict = {
             'waiter_callable': waiter_callable,
@@ -186,7 +190,7 @@
 
     def create_server(self, name=None, image=None, flavor=None,
                       wait_on_boot=True, wait_on_delete=True,
-                      create_kwargs={}):
+                      create_kwargs=None):
         """Creates VM instance.
 
         @param image: image from which to create the instance
@@ -201,6 +205,8 @@
             image = CONF.compute.image_ref
         if flavor is None:
             flavor = CONF.compute.flavor_ref
+        if create_kwargs is None:
+            create_kwargs = {}
 
         fixed_network_name = CONF.compute.fixed_network_name
         if 'nics' not in create_kwargs and fixed_network_name:
@@ -343,7 +349,9 @@
 
         return linux_client
 
-    def _image_create(self, name, fmt, path, properties={}):
+    def _image_create(self, name, fmt, path, properties=None):
+        if properties is None:
+            properties = {}
         name = data_utils.rand_name('%s-' % name)
         image_file = open(path, 'rb')
         self.addCleanup(image_file.close)
@@ -1022,8 +1030,8 @@
     def addCleanup_with_wait(self, things, thing_id,
                              error_status='ERROR',
                              exc_type=nova_exceptions.NotFound,
-                             cleanup_callable=None, cleanup_args=[],
-                             cleanup_kwargs={}):
+                             cleanup_callable=None, cleanup_args=None,
+                             cleanup_kwargs=None):
         """Adds wait for ansyc resource deletion at the end of cleanups
 
         @param things: type of the resource to delete
@@ -1035,6 +1043,10 @@
             usually a delete method. if not used, will try to use:
             things.delete(thing_id)
         """
+        if cleanup_args is None:
+            cleanup_args = []
+        if cleanup_kwargs is None:
+            cleanup_kwargs = {}
         if cleanup_callable is None:
             LOG.debug("no delete method passed. using {rclass}.delete({id}) as"
                       " default".format(rclass=things, id=thing_id))
@@ -1216,7 +1228,7 @@
 
     def create_server(self, client=None, name=None, image=None, flavor=None,
                       wait_on_boot=True, wait_on_delete=True,
-                      create_kwargs={}):
+                      create_kwargs=None):
         """Creates VM instance.
 
         @param client: compute client to create the instance
@@ -1234,6 +1246,8 @@
             image = CONF.compute.image_ref
         if flavor is None:
             flavor = CONF.compute.flavor_ref
+        if create_kwargs is None:
+            create_kwargs = {}
 
         fixed_network_name = CONF.compute.fixed_network_name
         if 'nics' not in create_kwargs and fixed_network_name:
@@ -1363,7 +1377,9 @@
         self.status_timeout(
             self.volume_client.volumes, volume_id, status)
 
-    def _image_create(self, name, fmt, path, properties={}):
+    def _image_create(self, name, fmt, path, properties=None):
+        if properties is None:
+            properties = {}
         name = data_utils.rand_name('%s-' % name)
         image_file = open(path, 'rb')
         self.addCleanup(image_file.close)
@@ -2375,12 +2391,17 @@
         self._list_and_check_container_objects(container_name,
                                                not_present_obj=[filename])
 
-    def _list_and_check_container_objects(self, container_name, present_obj=[],
-                                          not_present_obj=[]):
+    def _list_and_check_container_objects(self, container_name,
+                                          present_obj=None,
+                                          not_present_obj=None):
         """
         List objects for a given container and assert which are present and
         which are not.
         """
+        if present_obj is None:
+            present_obj = []
+        if not_present_obj is None:
+            not_present_obj = []
         _, object_list = self.container_client.list_container_contents(
             container_name)
         if present_obj:
diff --git a/tempest/services/object_storage/account_client.py b/tempest/services/object_storage/account_client.py
index be0f888..eca57c0 100644
--- a/tempest/services/object_storage/account_client.py
+++ b/tempest/services/object_storage/account_client.py
@@ -32,11 +32,15 @@
 
     def create_account(self, data=None,
                        params=None,
-                       metadata={},
-                       remove_metadata={},
+                       metadata=None,
+                       remove_metadata=None,
                        metadata_prefix='X-Account-Meta-',
                        remove_metadata_prefix='X-Remove-Account-Meta-'):
         """Create an account."""
+        if metadata is None:
+            metadata = {}
+        if remove_metadata is None:
+            remove_metadata = {}
         url = ''
         if params:
             url += '?%s' % urllib.urlencode(params)
diff --git a/tempest/services/orchestration/json/orchestration_client.py b/tempest/services/orchestration/json/orchestration_client.py
index 9c76f51..d3867cd 100644
--- a/tempest/services/orchestration/json/orchestration_client.py
+++ b/tempest/services/orchestration/json/orchestration_client.py
@@ -45,9 +45,11 @@
         body = json.loads(body)
         return resp, body['stacks']
 
-    def create_stack(self, name, disable_rollback=True, parameters={},
+    def create_stack(self, name, disable_rollback=True, parameters=None,
                      timeout_mins=60, template=None, template_url=None,
                      environment=None, files=None):
+        if parameters is None:
+            parameters = {}
         headers, body = self._prepare_update_create(
             name,
             disable_rollback,
@@ -63,8 +65,10 @@
         return resp, body
 
     def update_stack(self, stack_identifier, name, disable_rollback=True,
-                     parameters={}, timeout_mins=60, template=None,
+                     parameters=None, timeout_mins=60, template=None,
                      template_url=None, environment=None, files=None):
+        if parameters is None:
+            parameters = {}
         headers, body = self._prepare_update_create(
             name,
             disable_rollback,
@@ -80,9 +84,11 @@
         return resp, body
 
     def _prepare_update_create(self, name, disable_rollback=True,
-                               parameters={}, timeout_mins=60,
+                               parameters=None, timeout_mins=60,
                                template=None, template_url=None,
                                environment=None, files=None):
+        if parameters is None:
+            parameters = {}
         post_body = {
             "stack_name": name,
             "disable_rollback": disable_rollback,
@@ -264,16 +270,20 @@
         body = json.loads(body)
         return resp, body
 
-    def validate_template(self, template, parameters={}):
+    def validate_template(self, template, parameters=None):
         """Returns the validation result for a template with parameters."""
+        if parameters is None:
+            parameters = {}
         post_body = {
             'template': template,
             'parameters': parameters,
         }
         return self._validate_template(post_body)
 
-    def validate_template_url(self, template_url, parameters={}):
+    def validate_template_url(self, template_url, parameters=None):
         """Returns the validation result for a template with parameters."""
+        if parameters is None:
+            parameters = {}
         post_body = {
             'template_url': template_url,
             'parameters': parameters,
diff --git a/tempest/tests/test_hacking.py b/tempest/tests/test_hacking.py
index 52fdf7e..9c13013 100644
--- a/tempest/tests/test_hacking.py
+++ b/tempest/tests/test_hacking.py
@@ -107,3 +107,16 @@
         self.assertFalse(checks.no_official_client_manager_in_api_tests(
             "cls.official_client = clients.OfficialClientManager(credentials)",
             "tempest/scenario/fake_test.py"))
+
+    def test_no_mutable_default_args(self):
+        self.assertEqual(1, len(list(checks.no_mutable_default_args(
+            " def function1(para={}):"))))
+
+        self.assertEqual(1, len(list(checks.no_mutable_default_args(
+            "def function2(para1, para2, para3=[])"))))
+
+        self.assertEqual(0, len(list(checks.no_mutable_default_args(
+            "defined = []"))))
+
+        self.assertEqual(0, len(list(checks.no_mutable_default_args(
+            "defined, undefined = [], {}"))))
diff --git a/tools/check_logs.py b/tools/check_logs.py
index eab9f73..917aaaf 100755
--- a/tools/check_logs.py
+++ b/tools/check_logs.py
@@ -26,8 +26,9 @@
 import yaml
 
 
-is_grenade = (os.environ.get('DEVSTACK_GATE_GRENADE', "0") == "1" or
-              os.environ.get('DEVSTACK_GATE_GRENADE_FORWARD', "0") == "1")
+# DEVSTACK_GATE_GRENADE is either unset if grenade is not running
+# or a string describing what type of grenade run to perform.
+is_grenade = os.environ.get('DEVSTACK_GATE_GRENADE') is not None
 dump_all_errors = True
 
 # As logs are made clean, add to this set