Make '*' the default ml2 flat_networks configuration

Update the ml2 flat_networks configuration to set '*' as the
default because that has been effectively the default behavior due
to a bug with the empty list.

Also, fix the empty list configuration for disabling flat networks.

DocImpact
UpgradeImpact

Change-Id: I13eb22afd7c0d011154b58a1bd218fd4fa82a8d9
Closes-bug: #1437745
Co-Authored-By: Martin Hickey <martin.hickey@ie.ibm.com>

etc/neutron/plugins/ml2/ml2_conf.ini

@@ -61,12 +61,12 @@
 
 [ml2_type_flat]
 # (ListOpt) List of physical_network names with which flat networks
-# can be created. Use * to allow flat networks with arbitrary
-# physical_network names.
+# can be created. Use default '*' to allow flat networks with arbitrary
+# physical_network names. Use an empty list to disable flat networks.
 #
-# flat_networks =
+# flat_networks = *
 # Example:flat_networks = physnet1,physnet2
-# Example:flat_networks = *
+# Example:flat_networks =
 
 [ml2_type_vlan]
 # (ListOpt) List of <physical_network>[:<vlan_min>:<vlan_max>] tuples

neutron/plugins/ml2/drivers/type_flat.py

@@ -30,10 +30,11 @@ LOG = log.getLogger(__name__)
 
 flat_opts = [
     cfg.ListOpt('flat_networks',
-                default=[],
+                default='*',
                 help=_("List of physical_network names with which flat "
-                       "networks can be created. Use * to allow flat "
-                       "networks with arbitrary physical_network names."))
+                       "networks can be created. Use default '*' to allow "
+                       "flat networks with arbitrary physical_network names. "
+                       "Use an empty list to disable flat networks."))
 ]
 
 cfg.CONF.register_opts(flat_opts, "ml2_type_flat")
@@ -72,9 +73,8 @@ class FlatTypeDriver(helpers.BaseTypeDriver):
         if '*' in self.flat_networks:
             LOG.info(_LI("Arbitrary flat physical_network names allowed"))
             self.flat_networks = None
-        elif not all(self.flat_networks):
-            msg = _("physical network name is empty")
-            raise exc.InvalidInput(error_message=msg)
+        elif not self.flat_networks:
+            LOG.info(_LI("Flat networks are disabled"))
         else:
             LOG.info(_LI("Allowable flat physical_network names: %s"),
                      self.flat_networks)
@@ -93,6 +93,9 @@ class FlatTypeDriver(helpers.BaseTypeDriver):
         if not physical_network:
             msg = _("physical_network required for flat provider network")
             raise exc.InvalidInput(error_message=msg)
+        if self.flat_networks is not None and not self.flat_networks:
+            msg = _("Flat provider networks are disabled")
+            raise exc.InvalidInput(error_message=msg)
         if self.flat_networks and physical_network not in self.flat_networks:
             msg = (_("physical_network '%s' unknown for flat provider network")
                    % physical_network)

neutron/tests/unit/plugins/ml2/drivers/test_type_flat.py

@@ -19,6 +19,7 @@ from neutron.plugins.common import constants as p_const
 from neutron.plugins.ml2 import config
 from neutron.plugins.ml2 import driver_api as api
 from neutron.plugins.ml2.drivers import type_flat
+from neutron.tests import base
 from neutron.tests.unit import testlib_api
 
 
@@ -50,14 +51,21 @@ class FlatTypeTest(testlib_api.SqlTestCase):
         self.driver.validate_provider_segment(segment)
 
     def test_validate_provider_phynet_name(self):
+        self.driver._parse_networks([])
+        segment = {api.NETWORK_TYPE: p_const.TYPE_FLAT,
+                   api.PHYSICAL_NETWORK: 'flat_net1'}
         self.assertRaises(exc.InvalidInput,
-                          self.driver._parse_networks,
-                          entries=[''])
+                          self.driver.validate_provider_segment,
+                          segment=segment)
 
     def test_validate_provider_phynet_name_multiple(self):
-        self.assertRaises(exc.InvalidInput,
-                          self.driver._parse_networks,
-                          entries=['flat_net1', ''])
+        self.driver._parse_networks(['flat_net1', 'flat_net2'])
+        segment = {api.NETWORK_TYPE: p_const.TYPE_FLAT,
+                   api.PHYSICAL_NETWORK: 'flat_net1'}
+        self.driver.validate_provider_segment(segment)
+        segment = {api.NETWORK_TYPE: p_const.TYPE_FLAT,
+                   api.PHYSICAL_NETWORK: 'flat_net2'}
+        self.driver.validate_provider_segment(segment)
 
     def test_validate_provider_segment_without_physnet_restriction(self):
         self.driver._parse_networks('*')
@@ -133,3 +141,16 @@ class FlatTypeTest(testlib_api.SqlTestCase):
         config.cfg.CONF.set_override('path_mtu', 0, group='ml2')
         self.driver.physnet_mtus = {}
         self.assertEqual(0, self.driver.get_mtu('physnet1'))
+
+
+class FlatTypeDefaultTest(base.BaseTestCase):
+
+    def setUp(self):
+        super(FlatTypeDefaultTest, self).setUp()
+        self.driver = type_flat.FlatTypeDriver()
+        self.driver.physnet_mtus = []
+
+    def test_validate_provider_segment_default(self):
+        segment = {api.NETWORK_TYPE: p_const.TYPE_FLAT,
+                   api.PHYSICAL_NETWORK: 'other_flat_net'}
+        self.driver.validate_provider_segment(segment)