Move global service networking opts to new module

The my_ip, host and use_ipv6 options are used all over the codebase
and they're pretty well related to each other. Create a new netconf
module for them to live in.

There are now no options registered globally in nova.config!

blueprint: scope-config-opts
Change-Id: Ifde37839ae6f38e6bf99dff1e80b8e25fd68ed25

nova/netconf.py

@@ -0,0 +1,62 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# All Rights Reserved.
+# 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 socket
+
+from nova.openstack.common import cfg
+
+CONF = cfg.CONF
+
+
+def _get_my_ip():
+    """
+    Returns the actual ip of the local machine.
+
+    This code figures out what source address would be used if some traffic
+    were to be sent out to some well known address on the Internet. In this
+    case, a Google DNS server is used, but the specific address does not
+    matter much.  No traffic is actually sent.
+    """
+    try:
+        csock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        csock.connect(('8.8.8.8', 80))
+        (addr, port) = csock.getsockname()
+        csock.close()
+        return addr
+    except socket.error:
+        return "127.0.0.1"
+
+
+netconf_opts = [
+    cfg.StrOpt('my_ip',
+               default=_get_my_ip(),
+               help='ip address of this host'),
+    cfg.StrOpt('host',
+               default=socket.getfqdn(),
+               help='Name of this node.  This can be an opaque identifier.  '
+                    'It is not necessarily a hostname, FQDN, or IP address. '
+                    'However, the node name must be valid within '
+                    'an AMQP key, and if using ZeroMQ, a valid '
+                    'hostname, FQDN, or IP address'),
+    cfg.BoolOpt('use_ipv6',
+                default=False,
+                help='use ipv6'),
+]
+
+CONF.register_opts(netconf_opts)