Move libvirt VIF XML config into designer.py

There are a fixed set of sensible XML configurations for
network VIFs. Create some helper methods for configuring
these configurations. Then update the VIF drivers to call
these APIs. The 'designer.py' file will serve as a place
for any policy based XML configuration helpers, as distinct
from config.py which is purely dealing with XML parsing
and formatting

Blueprint: libvirt-vif-driver
Change-Id: I857607c15ed576c65f898df4eb7533505742324b
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

3 files changed, 138 insertions, 36 deletions

diff --git a/nova/virt/libvirt/config.py b/nova/virt/libvirt/config.py
index 222e6d52d..6785c8823 100644
--- a/nova/virt/libvirt/config.py
+++ b/nova/virt/libvirt/config.py
@@ -1,6 +1,6 @@
 # vim: tabstop=4 shiftwidth=4 softtabstop=4
 
-# Copyright (c) 2012 Red Hat, Inc.
+# Copyright (C) 2012-2013 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
@@ -18,7 +18,11 @@
 Configuration for libvirt objects.
 
 Classes to represent the configuration of various libvirt objects
-and support conversion to/from XML
+and support conversion to/from XML. These classes are solely concerned
+by providing direct Object <-> XML document conversions. No policy or
+operational decisions should be made by code in these classes. Such
+policy belongs in the 'designer.py' module which provides simplified
+helpers for populating up config object instances.
 """
 
 from nova import exception
diff --git a/nova/virt/libvirt/designer.py b/nova/virt/libvirt/designer.py
new file mode 100644
index 000000000..b832db4fa
--- /dev/null
+++ b/nova/virt/libvirt/designer.py
@@ -0,0 +1,101 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright (C) 2013 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.
+
+"""
+Policy based configuration of libvirt objects
+
+This module provides helper APIs for populating the config.py
+classes based on common operational needs / policies
+"""
+
+from nova.virt import netutils
+
+
+def set_vif_guest_frontend_config(conf, mac, model, driver):
+    """Populate a LibvirtConfigGuestInterface instance
+    with guest frontend details"""
+    conf.mac_addr = mac
+    if model is not None:
+        conf.model = model
+    if driver is not None:
+        conf.driver_name = driver
+
+
+def set_vif_host_backend_bridge_config(conf, brname, tapname=None):
+    """Populate a LibvirtConfigGuestInterface instance
+    with host backend details for a software bridge"""
+    conf.net_type = "bridge"
+    conf.source_dev = brname
+    if tapname:
+        conf.target_dev = tapname
+    conf.script = ""
+
+
+def set_vif_host_backend_ethernet_config(conf, tapname):
+    """Populate a LibvirtConfigGuestInterface instance
+    with host backend details for an externally configured
+    host device.
+
+    NB use of this configuration is discouraged by
+    libvirt project and will mark domains as 'tainted'"""
+
+    conf.net_type = "ethernet"
+    conf.target_dev = tapname
+    conf.script = ""
+
+
+def set_vif_host_backend_ovs_config(conf, brname, interfaceid, tapname=None):
+    """Populate a LibvirtConfigGuestInterface instance
+    with host backend details for an OpenVSwitch bridge"""
+
+    conf.net_type = "bridge"
+    conf.source_dev = brname
+    conf.vporttype = "openvswitch"
+    conf.add_vport_param("interfaceid", interfaceid)
+    if tapname:
+        conf.target_dev = tapname
+    conf.script = ""
+
+
+def set_vif_host_backend_filter_config(conf, name,
+                                       primary_addr,
+                                       dhcp_server=None,
+                                       ra_server=None,
+                                       allow_same_net=False,
+                                       ipv4_cidr=None,
+                                       ipv6_cidr=None):
+    """Populate a LibvirtConfigGuestInterface instance
+    with host backend details for traffic filtering"""
+
+    conf.filtername = name
+    conf.add_filter_param("IP", primary_addr)
+
+    if dhcp_server:
+        conf.add_filter_param("DHCPSERVER", dhcp_server)
+
+    if ra_server:
+        conf.add_filter_param("RASERVER", ra_server)
+
+    if allow_same_net:
+        if ipv4_cidr:
+            net, mask = netutils.get_net_and_mask(ipv4_cidr)
+            conf.add_filter_param("PROJNET", net)
+            conf.add_filter_param("PROJMASK", mask)
+
+        if ipv6_cidr:
+            net, prefix = netutils.get_net_and_prefixlen(ipv6_cidr)
+            conf.add_filter_param("PROJNET6", net)
+            conf.add_filter_param("PROJMASK6", prefix)
diff --git a/nova/virt/libvirt/vif.py b/nova/virt/libvirt/vif.py
index 1dc30f73e..0cf1b1658 100644
--- a/nova/virt/libvirt/vif.py
+++ b/nova/virt/libvirt/vif.py
@@ -24,10 +24,10 @@ from nova.network import linux_net
 from nova.openstack.common import cfg
 from nova.openstack.common import log as logging
 from nova import utils
-from nova.virt import netutils
 
 from nova.virt.libvirt import config as vconfig
-
+from nova.virt.libvirt import designer
+from nova.virt import netutils
 LOG = logging.getLogger(__name__)
 
 libvirt_vif_opts = [
@@ -51,14 +51,18 @@ class LibvirtBaseVIFDriver(object):
 
     def get_config(self, instance, network, mapping):
         conf = vconfig.LibvirtConfigGuestInterface()
-        conf.mac_addr = mapping['mac']
-        if CONF.libvirt_type in ('kvm', 'qemu') and \
-                CONF.libvirt_use_virtio_for_bridges:
-            conf.model = "virtio"
+        model = None
+        driver = None
+        if (CONF.libvirt_type in ('kvm', 'qemu') and
+            CONF.libvirt_use_virtio_for_bridges):
+            model = "virtio"
             # Workaround libvirt bug, where it mistakenly
             # enables vhost mode, even for non-KVM guests
             if CONF.libvirt_type == "qemu":
-                conf.driver_name = "qemu"
+                driver = "qemu"
+
+        designer.set_vif_guest_frontend_config(
+            conf, mapping['mac'], model, driver)
 
         return conf
 
@@ -75,28 +79,26 @@ class LibvirtBridgeDriver(LibvirtBaseVIFDriver):
                      self).get_config(instance,
                                       network,
                                       mapping)
-        conf.net_type = "bridge"
-        conf.source_dev = network['bridge']
-        conf.script = ""
 
-        conf.filtername = "nova-instance-" + instance['name'] + "-" + mac_id
-        conf.add_filter_param("IP", mapping['ips'][0]['ip'])
-        if mapping['dhcp_server']:
-            conf.add_filter_param("DHCPSERVER", mapping['dhcp_server'])
+        designer.set_vif_host_backend_bridge_config(
+            conf, network['bridge'], None)
 
-        if CONF.use_ipv6:
-            conf.add_filter_param("RASERVER",
-                                  mapping.get('gateway_v6') + "/128")
+        name = "nova-instance-" + instance['name'] + "-" + mac_id
+        primary_addr = mapping['ips'][0]['ip']
+        dhcp_server = ra_server = ipv4_cidr = ipv6_cidr = None
 
+        if mapping['dhcp_server']:
+            dhcp_server = mapping['dhcp_server']
+        if CONF.use_ipv6:
+            ra_server = mapping.get('gateway_v6') + "/128"
         if CONF.allow_same_net_traffic:
-            net, mask = netutils.get_net_and_mask(network['cidr'])
-            conf.add_filter_param("PROJNET", net)
-            conf.add_filter_param("PROJMASK", mask)
+            ipv4_cidr = network['cidr']
             if CONF.use_ipv6:
-                net_v6, prefixlen_v6 = netutils.get_net_and_prefixlen(
-                                           network['cidr_v6'])
-                conf.add_filter_param("PROJNET6", net_v6)
-                conf.add_filter_param("PROJMASK6", prefixlen_v6)
+                ipv6_cidr = network['cidr_v6']
+
+        designer.set_vif_host_backend_filter_config(
+            conf, name, primary_addr, dhcp_server,
+            ra_server, ipv4_cidr, ipv6_cidr)
 
         return conf
 
@@ -146,9 +148,7 @@ class LibvirtOpenVswitchDriver(LibvirtBaseVIFDriver):
                                       network,
                                       mapping)
 
-        conf.net_type = "ethernet"
-        conf.target_dev = dev
-        conf.script = ""
+        designer.set_vif_host_backend_ethernet_config(conf, dev)
 
         return conf
 
@@ -279,10 +279,8 @@ class LibvirtOpenVswitchVirtualPortDriver(LibvirtBaseVIFDriver):
                                       network,
                                       mapping)
 
-        conf.net_type = "bridge"
-        conf.source_dev = CONF.libvirt_ovs_bridge
-        conf.vporttype = "openvswitch"
-        conf.add_vport_param("interfaceid", mapping['vif_uuid'])
+        designer.set_vif_host_backend_ovs_config(
+            conf, CONF.libvirt_ovs_bridge, mapping['vif_uuid'])
 
         return conf
 
@@ -316,9 +314,8 @@ class QuantumLinuxBridgeVIFDriver(LibvirtBaseVIFDriver):
                                       network,
                                       mapping)
 
-        conf.target_dev = dev
-        conf.net_type = "bridge"
-        conf.source_dev = bridge
+        designer.set_vif_host_backend_bridge_config(
+            conf, bridge, dev)
 
         return conf