Move network_driver into new nova.network.driver

Add a new load_network_driver() function which constrains the use of the
network_driver option and move the option into nova.network.driver.

blueprint: scope-config-opts
Change-Id: I0a839765890093dc871b48435cfd113e0f8e46c4

nova/api/manager.py

@@ -17,11 +17,7 @@
 #    under the License.
 
 from nova import manager
-from nova.openstack.common import cfg
-from nova.openstack.common import importutils
-
-CONF = cfg.CONF
-CONF.import_opt('network_driver', 'nova.config')
+from nova.network import driver
 
 
 class MetadataManager(manager.Manager):
@@ -32,7 +28,7 @@ class MetadataManager(manager.Manager):
     """
     def __init__(self, *args, **kwargs):
         super(MetadataManager, self).__init__(*args, **kwargs)
-        self.network_driver = importutils.import_module(CONF.network_driver)
+        self.network_driver = driver.load_network_driver()
 
     def init_host(self):
         """Perform any initialization.

nova/config.py

@@ -158,9 +158,6 @@ global_opts = [
                default=None,
                help='The default format an ephemeral_volume will be '
                     'formatted with on creation.'),
-    cfg.StrOpt('network_driver',
-               default='nova.network.linux_net',
-               help='Driver to use for network creation'),
     cfg.BoolOpt('use_ipv6',
                 default=False,
                 help='use ipv6'),

nova/network/driver.py

@@ -0,0 +1,44 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2012 Red Hat, 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 sys
+
+from nova.openstack.common import cfg
+from nova.openstack.common import importutils
+from nova.openstack.common import log as logging
+
+driver_opts = [
+    cfg.StrOpt('network_driver',
+               default='nova.network.linux_net',
+               help='Driver to use for network creation'),
+]
+CONF = cfg.CONF
+CONF.register_opts(driver_opts)
+
+LOG = logging.getLogger(__name__)
+
+
+def load_network_driver(network_driver=None):
+    if not network_driver:
+        network_driver = CONF.network_driver
+
+    if not network_driver:
+        LOG.error(_("Network driver option required, but not specified"))
+        sys.exit(1)
+
+    LOG.info(_("Loading network driver '%s'") % CONF.network_driver)
+
+    return importutils.import_module(CONF.network_driver)

nova/network/manager.py

@@ -60,6 +60,7 @@ from nova import exception
 from nova import ipv6
 from nova import manager
 from nova.network import api as network_api
+from nova.network import driver
 from nova.network import model as network_model
 from nova.network import rpcapi as network_rpcapi
 from nova.openstack.common import cfg
@@ -189,7 +190,6 @@ network_opts = [
 CONF = cfg.CONF
 CONF.register_opts(network_opts)
 CONF.import_opt('fake_network', 'nova.config')
-CONF.import_opt('network_driver', 'nova.config')
 CONF.import_opt('use_ipv6', 'nova.config')
 CONF.import_opt('my_ip', 'nova.config')
 
@@ -909,9 +909,7 @@ class NetworkManager(manager.SchedulerDependentManager):
     required_create_args = []
 
     def __init__(self, network_driver=None, *args, **kwargs):
-        if not network_driver:
-            network_driver = CONF.network_driver
-        self.driver = importutils.import_module(network_driver)
+        self.driver = driver.load_network_driver(network_driver)
         self.instance_dns_manager = importutils.import_object(
                 CONF.instance_dns_manager)
         self.instance_dns_domain = CONF.instance_dns_domain

nova/tests/network/test_linux_net.py

@@ -21,16 +21,14 @@ import mox
 
 from nova import context
 from nova import db
+from nova.network import driver
 from nova.network import linux_net
-from nova.openstack.common import cfg
 from nova.openstack.common import fileutils
 from nova.openstack.common import importutils
 from nova.openstack.common import log as logging
 from nova import test
 from nova import utils
 
-CONF = cfg.CONF
-CONF.import_opt('network_driver', 'nova.config')
 LOG = logging.getLogger(__name__)
 
 HOST = "testhost"
@@ -214,8 +212,7 @@ class LinuxNetworkTestCase(test.TestCase):
 
     def setUp(self):
         super(LinuxNetworkTestCase, self).setUp()
-        network_driver = CONF.network_driver
-        self.driver = importutils.import_module(network_driver)
+        self.driver = driver.load_network_driver()
         self.driver.db = db
         self.context = context.RequestContext('testuser', 'testproject',
                                               is_admin=True)