Allows --flat_interface flag to override db

 * this replicates what commit 8efe15209 did for vlan_interface
 * includes a test to verify that the override works
 * cleans up memory usage in the vlan test
 * Fixes bug 944734

Change-Id: I21a04a43051f723029513c4c9548003f959cff37

3 files changed, 36 insertions, 5 deletions

diff --git a/nova/network/linux_net.py b/nova/network/linux_net.py
index 46d2aadd6..230755b81 100755
--- a/nova/network/linux_net.py
+++ b/nova/network/linux_net.py
@@ -951,9 +951,10 @@ class LinuxBridgeInterfaceDriver(LinuxNetInterfaceDriver):
                            network,
                            mac_address)
         else:
+            iface = FLAGS.flat_interface or network['bridge_interface']
             LinuxBridgeInterfaceDriver.ensure_bridge(
                           network['bridge'],
-                          network['bridge_interface'],
+                          iface,
                           network, gateway)
 
         # NOTE(vish): applying here so we don't get a lock conflict
diff --git a/nova/tests/test_linux_net.py b/nova/tests/test_linux_net.py
index 1c57220d5..39a5d3bed 100644
--- a/nova/tests/test_linux_net.py
+++ b/nova/tests/test_linux_net.py
@@ -421,9 +421,11 @@ class LinuxNetworkTestCase(test.TestCase):
 
         driver = linux_net.LinuxBridgeInterfaceDriver()
 
+        info = {}
+
         @classmethod
         def test_ensure(_self, vlan, bridge, interface, network, mac_address):
-            self.passed_interface = interface
+            info['passed_interface'] = interface
 
         self.stubs.Set(linux_net.LinuxBridgeInterfaceDriver,
                        'ensure_vlan_bridge', test_ensure)
@@ -434,10 +436,37 @@ class LinuxNetworkTestCase(test.TestCase):
                 "vlan": "fake"
         }
         driver.plug(network, "fakemac")
-        self.assertEqual(self.passed_interface, "base_interface")
+        self.assertEqual(info['passed_interface'], "base_interface")
         self.flags(vlan_interface="override_interface")
         driver.plug(network, "fakemac")
-        self.assertEqual(self.passed_interface, "override_interface")
+        self.assertEqual(info['passed_interface'], "override_interface")
+        driver.plug(network, "fakemac")
+
+    def test_flat_override(self):
+        """Makes sure flat_interface flag overrides network bridge_interface.
+
+        Allows heterogeneous networks a la bug 833426"""
+
+        driver = linux_net.LinuxBridgeInterfaceDriver()
+
+        info = {}
+
+        @classmethod
+        def test_ensure(_self, bridge, interface, network, gateway):
+            info['passed_interface'] = interface
+
+        self.stubs.Set(linux_net.LinuxBridgeInterfaceDriver,
+                       'ensure_bridge', test_ensure)
+
+        network = {
+                "bridge": "br100",
+                "bridge_interface": "base_interface",
+        }
+        driver.plug(network, "fakemac")
+        self.assertEqual(info['passed_interface'], "base_interface")
+        self.flags(flat_interface="override_interface")
+        driver.plug(network, "fakemac")
+        self.assertEqual(info['passed_interface'], "override_interface")
 
     def _test_initialize_gateway(self, existing, expected, routes=''):
         self.flags(fake_network=False)
diff --git a/nova/virt/libvirt/vif.py b/nova/virt/libvirt/vif.py
index 268a84525..ada4a7701 100644
--- a/nova/virt/libvirt/vif.py
+++ b/nova/virt/libvirt/vif.py
@@ -90,10 +90,11 @@ class LibvirtBridgeDriver(VIFDriver):
                                              network['bridge'],
                                              iface)
             else:
+                iface = FLAGS.flat_interface or network['bridge_interface']
                 LOG.debug(_("Ensuring bridge %s"), network['bridge'])
                 linux_net.LinuxBridgeInterfaceDriver.ensure_bridge(
                                         network['bridge'],
-                                        network['bridge_interface'])
+                                        iface)
 
         return self._get_configurations(network, mapping)