Check for hybrid plugging in OVS

There is a cold migration scenario that leaves some interfaces behind in
case port binding changes from hybrid to direct plugging between the
nodes. This patch adds functionality that checks presence of
intermediate linux bridge and clears things up properly if found.

Signed-off-by: Jakub Libosvar <libosvar@redhat.com>
Change-Id: Ic5b38a0467b3c18e38bec005d80cd1f5f0e66b28

releasenotes/notes/OVSVif-hybrid-unplug-f37bf57bc8e913de.yaml

@@ -0,0 +1,10 @@
+---
+
+feature:
+  - |
+    The unplug() method for VIFOpenVSwitch type now checks for existence of
+    linux bridge used in hybrid plugging mechanism. In case it exists, the
+    interfaces related to the hybrid plugging are deleted too. This is useful
+    in particular for cold migration use case when target node has updated
+    port binding that doesn't use hybrid plugging, while the original plugging
+    was hybrid.

vif_plug_ovs/ovs.py

@@ -363,7 +363,7 @@ class OvsPlugin(plugin.PluginBase):
                 constants.OVS_VHOSTUSER_PREFIX,
                 vif.id))
 
-    def _unplug_bridge(self, vif, instance_info):
+    def _unplug_bridge(self, vif, instance_info, linux_bridge_name):
         """UnPlug using hybrid strategy
 
         Unhook port from OVS, unhook port from bridge, delete
@@ -372,7 +372,7 @@ class OvsPlugin(plugin.PluginBase):
 
         v1_name, v2_name = self.get_veth_pair_names(vif)
 
-        linux_net.delete_bridge(vif.bridge_name, v1_name)
+        linux_net.delete_bridge(linux_bridge_name, v1_name)
 
         self.ovsdb.delete_ovs_vif_port(vif.network.bridge, v2_name)
 
@@ -439,9 +439,13 @@ class OvsPlugin(plugin.PluginBase):
             if self.config.per_port_bridge:
                 self._unplug_port_bridge(vif, instance_info)
             else:
-                self._unplug_vif_generic(vif, instance_info)
+                linux_bridge_name = self.gen_port_name('qbr', vif.id)
+                if ip_lib.exists(linux_bridge_name):
+                    self._unplug_bridge(vif, instance_info, linux_bridge_name)
+                else:
+                    self._unplug_vif_generic(vif, instance_info)
         elif isinstance(vif, objects.vif.VIFBridge):
-            self._unplug_bridge(vif, instance_info)
+            self._unplug_bridge(vif, instance_info, vif.bridge_name)
         elif isinstance(vif, objects.vif.VIFVHostUser):
             self._unplug_vhostuser(vif, instance_info)
         elif isinstance(vif, objects.vif.VIFHostDevice):

vif_plug_ovs/tests/unit/test_plugin.py

@@ -588,3 +588,17 @@ class PluginTest(testtools.TestCase):
         ]
         delete_ovs_vif_port.assert_has_calls(calls)
         delete_ovs_bridge.assert_called_once_with('pbb679325f-ca8')
+
+    @mock.patch.object(ip_lib, 'exists', return_value=True)
+    @mock.patch.object(ovs.OvsPlugin, '_unplug_bridge')
+    def test_unplug_hybrid_bridge(self, m_unplug_bridge, m_ip_lib_exists):
+        plugin = ovs.OvsPlugin.load(constants.PLUGIN_NAME)
+        plugin.unplug(self.vif_ovs, self.instance)
+        m_unplug_bridge.assert_called_once()
+
+    @mock.patch.object(ip_lib, 'exists', return_value=False)
+    @mock.patch.object(ovs.OvsPlugin, '_unplug_vif_generic')
+    def test_unplug_ovs(self, m_unplug_generic, m_ip_lib_exists):
+        plugin = ovs.OvsPlugin.load(constants.PLUGIN_NAME)
+        plugin.unplug(self.vif_ovs, self.instance)
+        m_unplug_generic.assert_called_once()