Modify to use libraries compatible with python3

This commit addresses some of the issues seen with compatibility of libraries
in 'congress-devstack-py35-api-mysql' gate job.

Partial-Bug:#1731141
Change-Id: I2cd487a712c3f5a6b113f7446d498add32eee9ab

services/policy/policy_client.py

@@ -13,8 +13,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import json
-
+from oslo_serialization import jsonutils as json
 from tempest.lib.common import rest_client
 
 

tests/scenario/congress_ha/test_ha.py

@@ -15,11 +15,11 @@
 
 import os
 import socket
-from StringIO import StringIO
 import subprocess
 import tempfile
 
 from oslo_log import log as logging
+import six
 from tempest.common import credentials_factory as credentials
 from tempest import config
 from tempest.lib.common.utils import test_utils
@@ -219,7 +219,7 @@ class TestHA(manager_congress.ScenarioPolicyBase):
                         LOG.debug("Replica port %s service %s logs: %s",
                                   port_num,
                                   service_key,
-                                  StringIO(output).getvalue())
+                                  six.StringIO(output.decode()).getvalue())
                 raise exceptions.TimeoutException("Replica Server not ready")
             # Relica server is up
             replica_server = True

tests/scenario/test_congress_basic_ops.py

@@ -14,6 +14,10 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import random
+import string
+import time
+
 from tempest.common import utils
 from tempest import config
 from tempest.lib.common.utils import test_utils
@@ -23,11 +27,6 @@ from tempest.lib import exceptions
 from congress_tempest_tests.tests.scenario import helper
 from congress_tempest_tests.tests.scenario import manager_congress
 
-import random
-import string
-import time
-
-
 CONF = config.CONF
 
 
@@ -49,7 +48,7 @@ class TestPolicyBasicOps(manager_congress.ScenarioPolicyBase):
         self.servers = []
 
     def _create_random_policy(self):
-        policy_name = "nova_%s" % ''.join(random.choice(string.lowercase)
+        policy_name = "nova_%s" % ''.join(random.choice(string.ascii_lowercase)
                                           for x in range(10))
         body = {"name": policy_name}
         resp = self.os_admin.congress_client.create_policy(body)