Drop using six library

Since we dropped python 2 support and testing in[1], there is
no compatibility with Python2 now. We can stop using python
six module.

[1] https://review.opendev.org/#/c/698245/

Change-Id: I15771f129ada53f1f8ca6683c8d80d5675332db5

lower-constraints.txt

@@ -124,7 +124,6 @@ rfc3986==0.3.1
 Routes==2.3.1
 ryu==4.24
 simplejson==3.5.1
-six==1.10.0
 snowballstemmer==1.2.1
 Sphinx==1.6.2
 sphinxcontrib-websupport==1.0.1

neutron_vpnaas/__init__.py

@@ -15,11 +15,5 @@
 
 import gettext
 
-import six
 
-
-if six.PY2:
-    # pylint: disable=unexpected-keyword-arg
-    gettext.install('neutron', unicode=1)
-else:
-    gettext.install('neutron')
+gettext.install('neutron')

neutron_vpnaas/extensions/vpn_endpoint_groups.py

@@ -14,8 +14,6 @@
 
 import abc
 
-import six
-
 from neutron.api.v2 import resource_helper
 
 from neutron_lib.api import converters
@@ -98,8 +96,7 @@ class Vpn_endpoint_groups(extensions.ExtensionDescriptor):
         return {}
 
 
-@six.add_metaclass(abc.ABCMeta)
-class VPNEndpointGroupsPluginBase(object):
+class VPNEndpointGroupsPluginBase(object, metaclass=abc.ABCMeta):
 
     @abc.abstractmethod
     def create_endpoint_group(self, context, endpoint_group):

neutron_vpnaas/extensions/vpnaas.py

@@ -23,8 +23,6 @@ from neutron_lib import exceptions as nexception
 from neutron_lib.plugins import constants as nconstants
 from neutron_lib.services import base as service_base
 
-import six
-
 from neutron.api.v2 import resource_helper
 
 from neutron_vpnaas._i18n import _
@@ -514,8 +512,7 @@ class Vpnaas(extensions.ExtensionDescriptor):
         return {}
 
 
-@six.add_metaclass(abc.ABCMeta)
-class VPNPluginBase(service_base.ServicePluginBase):
+class VPNPluginBase(service_base.ServicePluginBase, metaclass=abc.ABCMeta):
 
     def get_plugin_type(self):
         return nconstants.VPN

neutron_vpnaas/services/vpn/common/netns_wrapper.py

@@ -13,6 +13,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import configparser as ConfigParser
 import errno
 import os
 import sys
@@ -24,15 +25,9 @@ from neutron_lib.utils import helpers
 from oslo_config import cfg
 from oslo_log import log as logging
 from oslo_rootwrap import wrapper
-import six
 
 from neutron_vpnaas._i18n import _
 
-if six.PY3:
-    import configparser as ConfigParser
-else:
-    import ConfigParser
-
 LOG = logging.getLogger(__name__)
 
 

neutron_vpnaas/services/vpn/device_drivers/__init__.py

@@ -14,11 +14,8 @@
 #    under the License.
 import abc
 
-import six
 
-
-@six.add_metaclass(abc.ABCMeta)
-class DeviceDriver(object):
+class DeviceDriver(object, metaclass=abc.ABCMeta):
 
     def __init__(self, agent, host):
         pass

neutron_vpnaas/services/vpn/device_drivers/ipsec.py

@@ -40,7 +40,6 @@ import oslo_messaging
 from oslo_service import loopingcall
 from oslo_utils import encodeutils
 from oslo_utils import fileutils
-import six
 
 from neutron_vpnaas._i18n import _
 from neutron_vpnaas.extensions import vpnaas
@@ -134,8 +133,7 @@ def _get_template(template_file):
     return JINJA_ENV.get_template(template_file)
 
 
-@six.add_metaclass(abc.ABCMeta)
-class BaseSwanProcess(object):
+class BaseSwanProcess(object, metaclass=abc.ABCMeta):
     """Swan Family Process Manager
 
     This class manages start/restart/stop ipsec process.
@@ -796,8 +794,7 @@ class IPsecVpnDriverApi(object):
         return cctxt.call(context, 'update_status', status=status)
 
 
-@six.add_metaclass(abc.ABCMeta)
-class IPsecDriver(device_drivers.DeviceDriver):
+class IPsecDriver(device_drivers.DeviceDriver, metaclass=abc.ABCMeta):
     """VPN Device Driver for IPSec.
 
     This class is designed for use with L3-agent now.

neutron_vpnaas/services/vpn/service_drivers/__init__.py

@@ -20,15 +20,13 @@ from neutron_lib.plugins import directory
 from neutron_lib import rpc as n_rpc
 from oslo_log import log as logging
 import oslo_messaging
-import six
 
 from neutron_vpnaas.services.vpn.service_drivers import driver_validator
 
 LOG = logging.getLogger(__name__)
 
 
-@six.add_metaclass(abc.ABCMeta)
-class VpnDriver(object):
+class VpnDriver(object, metaclass=abc.ABCMeta):
 
     def __init__(self, service_plugin, validator=None):
         self.service_plugin = service_plugin

neutron_vpnaas/services/vpn/service_drivers/base_ipsec.py

@@ -16,7 +16,6 @@ import abc
 
 import netaddr
 import oslo_messaging
-import six
 
 from neutron.db.models import l3agent
 from neutron.db.models import servicetype
@@ -97,8 +96,7 @@ class IPsecVpnAgentApi(service_drivers.BaseIPsecVpnAgentApi):
             topic, default_version, driver)
 
 
-@six.add_metaclass(abc.ABCMeta)
-class BaseIPsecVPNDriver(service_drivers.VpnDriver):
+class BaseIPsecVPNDriver(service_drivers.VpnDriver, metaclass=abc.ABCMeta):
     """Base VPN Service Driver class."""
 
     def __init__(self, service_plugin, validator=None):

requirements.txt

@@ -8,7 +8,6 @@ Jinja2>=2.10 # BSD License (3 clause)
 netaddr>=0.7.18 # BSD
 SQLAlchemy>=1.2.0 # MIT
 alembic>=0.8.10 # MIT
-six>=1.10.0 # MIT
 neutron-lib>=1.18.0 # Apache-2.0
 oslo.concurrency>=3.26.0 # Apache-2.0
 oslo.config>=5.2.0 # Apache-2.0