Use flake8-import-order plugin and clean up exceptions

1. In reviews we usually check import grouping but it is boring.
By using flake8-import-order plugin, we can avoid this.
It enforces loose checking so it sounds good to use it.
This flake8 plugin is already used in tempest.

Note that flake8-import-order version is pinned to avoid unexpected
breakage of pep8 job.

Setup for unit tests of hacking rules is tweaked to disable
flake8-import-order checks. This extension assumes an actual file
exists and causes hacking rule unit tests.

2. This patch is also intend to clean up exceptions to avoid
confusing for other developers and the maintenance-ability as well.

Change-Id: I032892f08e073feb5b822d27d092f041b17d57e1

neutron_vpnaas/__init__.py

@@ -14,6 +14,7 @@
 #    under the License.
 
 import gettext
+
 import six
 
 

neutron_vpnaas/db/migration/alembic_migrations/env.py

@@ -12,8 +12,9 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-from alembic import context
 from logging import config as logging_config
+
+from alembic import context
 from neutron_lib.db import model_base
 from oslo_config import cfg
 from oslo_db.sqlalchemy import session

neutron_vpnaas/db/vpn/vpn_validator.py

@@ -12,9 +12,9 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import netaddr
 import socket
 
+import netaddr
 from neutron.db import l3_db
 from neutron.db import models_v2
 from neutron_lib.api import validators

neutron_vpnaas/services/vpn/device_drivers/cisco_ipsec.py

@@ -13,7 +13,6 @@
 #    under the License.
 
 import collections
-import requests
 
 from neutron.common import rpc as n_rpc
 from neutron.plugins.common import utils as plugin_utils
@@ -25,6 +24,7 @@ from oslo_config import cfg
 from oslo_log import log as logging
 import oslo_messaging
 from oslo_service import loopingcall
+import requests
 
 from neutron_vpnaas._i18n import _
 from neutron_vpnaas.services.vpn.common import topics

neutron_vpnaas/services/vpn/device_drivers/ipsec.py

@@ -18,7 +18,6 @@ import filecmp
 import os
 import re
 import shutil
-import six
 import socket
 
 import eventlet
@@ -39,6 +38,7 @@ from oslo_log import helpers as log_helpers
 from oslo_log import log as logging
 import oslo_messaging
 from oslo_service import loopingcall
+import six
 
 from neutron_vpnaas._i18n import _
 from neutron_vpnaas.extensions import vpnaas

neutron_vpnaas/tests/functional/common/test_scenario.py

@@ -13,11 +13,10 @@
 import collections
 import copy
 import functools
+import os
+
 import mock
 import netaddr
-import os
-import testtools
-
 from neutron.agent.common import ovs_lib
 from neutron.agent.l3 import namespaces as n_namespaces
 from neutron.agent.l3 import router_info
@@ -38,6 +37,7 @@ from neutron_lib.utils import net as n_utils
 from oslo_config import cfg
 from oslo_log import log as logging
 from oslo_utils import uuidutils
+import testtools
 
 from neutron_vpnaas.services.vpn import agent as vpn_agent
 from neutron_vpnaas.services.vpn.agent import vpn_agent_opts

neutron_vpnaas/tests/functional/strongswan/test_strongswan_driver.py

@@ -13,9 +13,9 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
 import os
 
+import mock
 from neutron.agent.l3 import legacy_router
 from neutron.conf.agent.l3 import config as l3_config
 from neutron.tests.functional import base

neutron_vpnaas/tests/unit/db/vpn/test_vpn_validator.py

@@ -13,9 +13,9 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
 import socket
 
+import mock
 from neutron.db import l3_db
 from neutron.db import servicetype_db as st_db
 from neutron_lib import context as n_ctx

neutron_vpnaas/tests/unit/extensions/test_vpnaas.py

@@ -14,6 +14,7 @@
 #    under the License.
 
 import copy
+
 import mock
 from neutron.tests.unit.api.v2 import test_base as test_api_v2
 from neutron_lib.plugins import constants as nconstants

neutron_vpnaas/tests/unit/services/vpn/device_drivers/test_ipsec.py

@@ -15,10 +15,10 @@
 import copy
 import difflib
 import io
-import mock
 import os
 import socket
 
+import mock
 from neutron.agent.l3 import dvr_edge_router
 from neutron.agent.l3 import dvr_snat_ns
 from neutron.agent.l3 import legacy_router

rally-jobs/plugins/vpn_base.py

@@ -13,7 +13,6 @@
 # under the License.
 
 import concurrent.futures
-import exceptions
 import re
 import threading
 import time
@@ -330,7 +329,7 @@ class VpnBase(rally_base.OpenStackScenario):
                 return resource
             time.sleep(check_interval)
             if time.time() - start_time > wait_timeout:
-                raise exceptions.Exception(
+                raise Exception(
                     "Timeout waiting for resource {} to change to {} status".
                     format(resource[resource_tag]['name'], final_status))
 

rally-jobs/plugins/vpn_utils.py

@@ -12,13 +12,12 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-import exceptions
 import os
-import paramiko
 import socket
 import stat
 import time
 
+import paramiko
 from rally.common import logging
 from rally.plugins.openstack.wrappers import network as network_wrapper
 from rally.task import utils as task_utils
@@ -48,25 +47,21 @@ def execute_cmd_over_ssh(host, cmd, private_key):
 
         client.connect(host["ip"], username=host["username"], pkey=k)
     except paramiko.BadHostKeyException as e:
-        raise exceptions.Exception(
+        raise Exception(
-                "BADHOSTKEY EXCEPTION WHEN CONNECTING TO %s", host["ip"], e)
+            "BADHOSTKEY EXCEPTION WHEN CONNECTING TO %s", host["ip"], e)
     except paramiko.AuthenticationException as e:
-        raise exceptions.Exception(
+        raise Exception(
-                "AUTHENTICATION EXCEPTION WHEN CONNECTING TO %s",
+            "AUTHENTICATION EXCEPTION WHEN CONNECTING TO %s", host["ip"], e)
-                host["ip"], e)
     except paramiko.SSHException as e:
-        raise exceptions.Exception(
+        raise Exception("SSH EXCEPTION WHEN CONNECTING TO %s", host["ip"], e)
-                "SSH EXCEPTION WHEN CONNECTING TO %s", host["ip"], e)
     except socket.error as e:
-        raise exceptions.Exception(
+        raise Exception("SOCKET ERROR WHEN CONNECTING TO %s", host["ip"], e)
-                "SOCKET ERROR WHEN CONNECTING TO %s", host["ip"], e)
     LOG.debug("CONNECTED TO HOST <%s>", host["ip"])
     try:
         stdin, stdout, stderr = client.exec_command(cmd)
         return stdout.read().splitlines()
     except paramiko.SSHException as e:
-        raise exceptions.Exception(
+        raise Exception("SSHEXCEPTION WHEN CONNECTING TO %s", host["ip"], e)
-                "SSHEXCEPTION WHEN CONNECTING TO %s", host["ip"], e)
     finally:
         client.close()
 
@@ -237,7 +232,7 @@ def write_key_to_compute_node(keypair, local_path, remote_path, host,
     try:
         transport = paramiko.Transport(host['ip'], host['port'])
     except paramiko.SSHException as e:
-        raise exceptions.Exception(
+        raise Exception(
             "PARAMIKO TRANSPORT FAILED. CHECK IF THE HOST IP %s AND PORT %s "
             "ARE CORRECT %s", host['ip'], host['port'], e)
     try:
@@ -245,24 +240,22 @@ def write_key_to_compute_node(keypair, local_path, remote_path, host,
                 username=host['username'], pkey=k)
     except paramiko.BadHostKeyException as e:
         transport.close()
-        raise exceptions.Exception(
+        raise Exception(
-                "BADHOSTKEY EXCEPTION WHEN CONNECTING TO %s", host["ip"], e)
+            "BADHOSTKEY EXCEPTION WHEN CONNECTING TO %s", host["ip"], e)
     except paramiko.AuthenticationException as e:
         transport.close()
-        raise exceptions.Exception(
+        raise Exception("AUTHENTICATION EXCEPTION WHEN CONNECTING TO %s",
-                "AUTHENTICATION EXCEPTION WHEN CONNECTING TO %s",
+                        host["ip"], e)
-                host["ip"], e)
     except paramiko.SSHException as e:
         transport.close()
-        raise exceptions.Exception(
+        raise Exception("SSH EXCEPTION WHEN CONNECTING TO %s", host["ip"], e)
-                "SSH EXCEPTION WHEN CONNECTING TO %s", host["ip"], e)
     LOG.debug("CONNECTED TO HOST <%s>", host["ip"])
 
     try:
         sftp_client = paramiko.SFTPClient.from_transport(transport)
         sftp_client.put(local_path, remote_path)
     except IOError as e:
-        raise exceptions.Exception("FILE PATH DOESN'T EXIST", e)
+        raise Exception("FILE PATH DOESN'T EXIST", e)
     finally:
         transport.close()
 
@@ -391,8 +384,8 @@ def wait_for_namespace_creation(namespace_tag, router_id, hosts, private_key,
                     return namespace_tag, host
         time.sleep(1)
         if time.time() - start_time > timeout:
-            raise exceptions.Exception("TIMEOUT WHILE WAITING FOR"
+            raise Exception("TIMEOUT WHILE WAITING FOR"
-                                       " NAMESPACES TO BE CREATED")
+                            " NAMESPACES TO BE CREATED")
 
 
 def ping(host, cmd, private_key):

test-requirements.txt

@@ -6,6 +6,7 @@ hacking!=0.13.0,<0.14,>=0.12.0 # Apache-2.0
 astroid<1.4.0 # LGPLv2.1 # breaks pylint 1.4.4
 coverage!=4.4,>=4.0 # Apache-2.0
 fixtures>=3.0.0 # Apache-2.0/BSD
+flake8-import-order==0.12 # LGPLv3
 mock>=2.0 # BSD
 pylint==1.4.5 # GPLv2
 python-subunit>=0.0.18 # Apache-2.0/BSD

tox.ini

@@ -90,6 +90,7 @@ commands = sphinx-build -W -b html doc/source doc/build
 ignore = E125,E126,E128,E129,E265,H404,H405,N530,N531
 show-source = true
 exclude = .venv,.git,.tox,dist,doc,.tmp,*lib/python*,*egg,build,tools,.ropeproject,rally-scenarios
+import-order-style = pep8
 
 [hacking]
 import_exceptions = neutron_vpnaas._i18n