Allow older versions of libvirt to delete vms

Libvirt < 0.9.4 doesn't support undefineFlags, so the vms can't be
deleted. This patch adds a workaround to fallback to the old style
of undefine if undefineFlags throws an Attribute error. It also
attempts to remove any managed save images that exist.

Fixes bug 1051010

Change-Id: I155fe2ab3be347b1515c5aab4a9233921bd722ca

nova/tests/test_libvirt.py

@@ -2165,8 +2165,7 @@ class LibvirtConnTestCase(test.TestCase):
         instance = db.instance_create(self.context, self.test_instance)
         conn.destroy(instance, {})
 
-    def test_destroy(self):
+    def test_destroy_undefines(self):
-        """Ensure destroy calls virDomain.undefineFlags"""
         mock = self.mox.CreateMock(libvirt.virDomain)
         mock.destroy()
         mock.undefineFlags(1).AndReturn(1)
@@ -2186,9 +2185,7 @@ class LibvirtConnTestCase(test.TestCase):
                     "uuid": "875a8070-d0b9-4949-8b31-104d125c9a64"}
         conn.destroy(instance, [])
 
-    def test_destroy_noflag(self):
+    def test_destroy_undefines_no_undefine_flags(self):
-        """Ensure destroy calls virDomain.undefine
-        if mock.undefineFlags raises an error"""
         mock = self.mox.CreateMock(libvirt.virDomain)
         mock.destroy()
         mock.undefineFlags(1).AndRaise(libvirt.libvirtError('Err'))
@@ -2209,6 +2206,51 @@ class LibvirtConnTestCase(test.TestCase):
                     "uuid": "875a8070-d0b9-4949-8b31-104d125c9a64"}
         conn.destroy(instance, [])
 
+    def test_destroy_undefines_no_attribute_with_managed_save(self):
+        mock = self.mox.CreateMock(libvirt.virDomain)
+        mock.destroy()
+        mock.undefineFlags(1).AndRaise(AttributeError())
+        mock.hasManagedSaveImage(0).AndReturn(True)
+        mock.managedSaveRemove(0)
+        mock.undefine()
+
+        self.mox.ReplayAll()
+
+        def fake_lookup_by_name(instance_name):
+            return mock
+
+        def fake_get_info(instance_name):
+            return {'state': power_state.SHUTDOWN}
+
+        conn = libvirt_driver.LibvirtDriver(False)
+        self.stubs.Set(conn, '_lookup_by_name', fake_lookup_by_name)
+        self.stubs.Set(conn, 'get_info', fake_get_info)
+        instance = {"name": "instancename", "id": "instanceid",
+                    "uuid": "875a8070-d0b9-4949-8b31-104d125c9a64"}
+        conn.destroy(instance, [])
+
+    def test_destroy_undefines_no_attribute_no_managed_save(self):
+        mock = self.mox.CreateMock(libvirt.virDomain)
+        mock.destroy()
+        mock.undefineFlags(1).AndRaise(AttributeError())
+        mock.hasManagedSaveImage(0).AndRaise(AttributeError())
+        mock.undefine()
+
+        self.mox.ReplayAll()
+
+        def fake_lookup_by_name(instance_name):
+            return mock
+
+        def fake_get_info(instance_name):
+            return {'state': power_state.SHUTDOWN}
+
+        conn = libvirt_driver.LibvirtDriver(False)
+        self.stubs.Set(conn, '_lookup_by_name', fake_lookup_by_name)
+        self.stubs.Set(conn, 'get_info', fake_get_info)
+        instance = {"name": "instancename", "id": "instanceid",
+                    "uuid": "875a8070-d0b9-4949-8b31-104d125c9a64"}
+        conn.destroy(instance, [])
+
     def test_private_destroy(self):
         """Ensure Instance not found skips undefine"""
         mock = self.mox.CreateMock(libvirt.virDomain)