deprecate `volume_api_class and network_api_class`

Both of these options only had one real in tree sensible
option. Deprecate these so they can be removed and turned into
constants in Newton.

This adds a new ``use_neutron`` config option to replace the
network_api_class option.

Change-Id: Ia79269e2bca0468edde830fc82a15b234e1abcbf

nova/network/__init__.py

@@ -15,19 +15,51 @@
 #    under the License.
 
 import oslo_config.cfg
+from oslo_log import log as logging
 from oslo_utils import importutils
 
+from nova.i18n import _LW
+
+LOG = logging.getLogger(__name__)
+
+NOVA_NET_API = 'nova.network.api.API'
+NEUTRON_NET_API = 'nova.network.neutronv2.api.API'
+
 _network_opts = [
     oslo_config.cfg.StrOpt('network_api_class',
-                           default='nova.network.api.API',
-                           help='The full class name of the '
-                                'network API class to use'),
+                           default=NOVA_NET_API,
+                           help='DEPRECATED: The full class name of the '
+                                'network API class to use. ``use_neutron`` '
+                                'should be used instead.',
+                           deprecated_for_removal=True),
+    oslo_config.cfg.BoolOpt('use_neutron',
+                            default=False,
+                            help="""
+Whether to use Neutron or Nova Network as the back end for networking.
+Defaults to False (indicating Nova network). Set to True to use neutron.
+""")
+
 ]
 
 oslo_config.cfg.CONF.register_opts(_network_opts)
 
 
 def API(skip_policy_check=False):
-    network_api_class = oslo_config.cfg.CONF.network_api_class
+    legacy_class = oslo_config.cfg.CONF.network_api_class
+    use_neutron = oslo_config.cfg.CONF.use_neutron
+
+    if legacy_class == NEUTRON_NET_API and not use_neutron:
+        # If they specified neutron via class, we should respect that
+        network_api_class = legacy_class
+        LOG.warn(_LW("Config mismatch. The network_api_class specifies %s, "
+                     "however use_neutron is not set to True. Using Neutron "
+                     "networking for now, however please set use_neutron to "
+                     "True in your configuration as network_api_class is "
+                     "deprecated and will be removed."), legacy_class)
+    elif use_neutron:
+        network_api_class = NEUTRON_NET_API
+    else:
+        network_api_class = NOVA_NET_API
+
     cls = importutils.import_class(network_api_class)
     return cls(skip_policy_check=skip_policy_check)

nova/tests/unit/network/test_config.py

@@ -0,0 +1,41 @@
+# Copyright 2016 HPE, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import nova.network
+import nova.test
+
+
+class NetworkAPIConfigTest(nova.test.NoDBTestCase):
+    """Test the transition from legacy to use_neutron config options."""
+
+    def test_default(self):
+        netapi = nova.network.API()
+        self.assertIsInstance(netapi, nova.network.api.API)
+
+    def test_use_neutron(self):
+        self.flags(use_neutron=True)
+        netapi = nova.network.API()
+        self.assertIsInstance(netapi, nova.network.neutronv2.api.API)
+
+    def test_dont_use_neutron(self):
+        self.flags(use_neutron=False)
+        netapi = nova.network.API()
+        self.assertIsInstance(netapi, nova.network.api.API)
+
+    def test_legacy_use_neutron(self):
+        """use neutron even if config is false because of legacy option."""
+        self.flags(use_neutron=False)
+        self.flags(network_api_class='nova.network.neutronv2.api.API')
+        netapi = nova.network.API()
+        self.assertIsInstance(netapi, nova.network.neutronv2.api.API)

nova/volume/__init__.py

@@ -18,10 +18,11 @@ import oslo_config.cfg
 from oslo_utils import importutils
 
 _volume_opts = [
-    oslo_config.cfg.StrOpt('volume_api_class',
-                                     default='nova.volume.cinder.API',
-                                     help='The full class name of the '
-                                          'volume API class to use'),
+    oslo_config.cfg.StrOpt(
+        'volume_api_class',
+        default='nova.volume.cinder.API',
+        help='DEPRECATED: The full class name of the volume API class to use',
+        deprecated_for_removal=True)
 ]
 
 oslo_config.cfg.CONF.register_opts(_volume_opts)

releasenotes/notes/rm_volume_manager-78fed5be43d285b3.yaml

@@ -0,0 +1,15 @@
+---
+upgrade:
+
+  - A new ``use_neutron`` option is introduced which replaces the
+    obtuse ``network_api_class`` option. This defaults to 'False' to
+    match existing defaults, however if ``network_api_class`` is set
+    to the known Neutron value Neutron networking will still be used
+    as before.
+
+deprecations:
+
+  - Deprecate ``volume_api_class`` and ``network_api_class`` config
+    options. We only have one sensible backend for either of
+    these. These options will be removed and turned into constants in
+    Newton.