Fix bug with not implemented virConnect.registerCloseCallback

The unit test test_connection_to_primitive fails many times due to
"virConnect instance has no attribute 'registerCloseCallback'".

registerCloseCallback has been added since original(community's)
python-libvirt v1.0.0, and v1.2.0 also contains the method.
However ubuntu cloud's v1.0.1 does not contain the method, and current
version check of python-libvirt does not work.
This patch tries to operate the method and catch TypeError exception if
the method does not exist instead of the version check.

Co-Authored-By: Sahid Orentino Ferdjaoui <sahid.ferdjaoui@cloudwatt.com>
Closes-Bug: #1266711
Change-Id: I4ec9ff9a684639ae5b146f400c90115c83afcda7

nova/tests/virt/libvirt/fakelibvirt.py

@@ -642,6 +642,9 @@ class Connection(object):
     def domainEventRegisterAny(self, dom, eventid, callback, opaque):
         self._event_callbacks[eventid] = [callback, opaque]
 
+    def registerCloseCallback(self, cb, opaque):
+        pass
+
     def getCapabilities(self):
         """Return spoofed capabilities."""
         return '''<capabilities>

nova/tests/virt/libvirt/test_libvirt.py

@@ -705,8 +705,15 @@ class LibvirtConnTestCase(test.TestCase):
         self.assertThat(expected, matchers.DictMatches(result))
 
     def test_close_callback(self):
-        def get_lib_version_stub():
+        class FakeConn(object):
-            return (1 * 1000 * 1000) + (0 * 1000) + 1
+            def getLibVersion(self):
+                return (1 * 1000 * 1000) + (0 * 1000) + 1
+
+            def domainEventRegisterAny(self, *args, **kwargs):
+                pass
+
+            def registerCloseCallback(self, cb, opaque):
+                pass
 
         self.close_callback = None
 
@@ -714,32 +721,80 @@ class LibvirtConnTestCase(test.TestCase):
             self.close_callback = cb
 
         conn = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)
-        self.stubs.Set(self.conn, "getLibVersion", get_lib_version_stub)
+        conn._wrapped_conn = FakeConn()
+
         self.mox.StubOutWithMock(conn, '_connect')
-        self.mox.StubOutWithMock(self.conn, 'registerCloseCallback')
+        self.mox.StubOutWithMock(conn._conn, 'registerCloseCallback')
         self.mox.StubOutWithMock(conn, 'set_host_enabled')
 
-        conn._connect(mox.IgnoreArg(), mox.IgnoreArg()).AndReturn(self.conn)
+        conn._connect(mox.IgnoreArg(), mox.IgnoreArg()).AndReturn(conn._conn)
-        self.conn.registerCloseCallback(
+        conn._conn.registerCloseCallback(
-            mox.IgnoreArg(), mox.IgnoreArg()).WithSideEffects(
+            mox.IgnoreArg(), mox.IgnoreArg()
-                set_close_callback)
+        ).WithSideEffects(set_close_callback)
         conn.set_host_enabled('fake-mini', True)
         conn.set_host_enabled('fake-mini', 'Connection to libvirt lost: 1')
-        conn._connect(mox.IgnoreArg(), mox.IgnoreArg()).AndReturn(self.conn)
+        conn._connect(mox.IgnoreArg(), mox.IgnoreArg()).AndReturn(conn._conn)
         conn.set_host_enabled('fake-mini', True)
-        self.conn.registerCloseCallback(mox.IgnoreArg(), mox.IgnoreArg())
+        conn._conn.registerCloseCallback(mox.IgnoreArg(), mox.IgnoreArg())
         self.mox.ReplayAll()
 
         # verify that the driver registers for the close callback
         # and re-connects after receiving the callback
-        conn._get_connection()
+        conn._get_new_connection()
 
         self.assertTrue(self.close_callback)
-        self.close_callback(self.conn, 1, None)
+        self.close_callback(conn._conn, 1, None)
 
         conn._get_connection()
         self.mox.UnsetStubs()
 
+    def test_close_callback_bad_signature(self):
+        class FakeConn(object):
+            def getLibVersion(self):
+                return (1 * 1000 * 1000) + (0 * 1000) + 0
+
+            def domainEventRegisterAny(self, *args, **kwargs):
+                pass
+
+            def registerCloseCallback(self, cb, opaque, *args, **kwargs):
+                pass
+
+        conn = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)
+        conn._wrapped_conn = FakeConn()
+
+        self.mox.StubOutWithMock(conn, '_connect')
+        self.mox.StubOutWithMock(conn._conn, 'registerCloseCallback')
+        self.mox.StubOutWithMock(conn, 'set_host_enabled')
+
+        conn._connect(mox.IgnoreArg(), mox.IgnoreArg()).AndReturn(conn._conn)
+        conn.set_host_enabled('fake-mini', True)
+        conn._conn.registerCloseCallback(
+            mox.IgnoreArg(), mox.IgnoreArg()).AndRaise(TypeError)
+
+        self.mox.ReplayAll()
+        conn._get_new_connection()
+
+    def test_close_callback_not_defined(self):
+        class FakeConn():
+            def getLibVersion(self):
+                return (0 * 1000 * 1000) + (9 * 1000) + 0
+
+            def domainEventRegisterAny(self, *args, **kwargs):
+                pass
+
+        conn = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)
+        conn._wrapped_conn = FakeConn()
+
+        self.mox.StubOutWithMock(conn, '_connect')
+        self.mox.StubOutWithMock(conn, 'set_host_enabled')
+
+        conn._connect(mox.IgnoreArg(), mox.IgnoreArg()).AndReturn(
+            conn._wrapped_conn)
+        conn.set_host_enabled('fake-mini', True)
+
+        self.mox.ReplayAll()
+        conn._get_new_connection()
+
     def test_cpu_features_bug_1217630(self):
         conn = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)
 
@@ -7606,18 +7661,26 @@ class LibvirtNonblockingTestCase(test.TestCase):
         jsonutils.to_primitive(connection._conn, convert_instances=True)
 
     def test_tpool_execute_calls_libvirt(self):
-        self.mox.StubOutWithMock(eventlet.tpool, 'execute')
         conn = libvirt.virConnect()
         conn.is_expected = True
+
+        self.mox.StubOutWithMock(eventlet.tpool, 'execute')
         eventlet.tpool.execute(
-            libvirt.openAuth, 'test:///default',
+            libvirt.openAuth,
-            mox.IgnoreArg(), mox.IgnoreArg()).AndReturn(conn)
+            'test:///default',
+            mox.IgnoreArg(),
+            mox.IgnoreArg()).AndReturn(conn)
         eventlet.tpool.execute(
             conn.domainEventRegisterAny,
             None,
             libvirt.VIR_DOMAIN_EVENT_ID_LIFECYCLE,
             mox.IgnoreArg(),
             mox.IgnoreArg())
+        if hasattr(libvirt.virConnect, 'registerCloseCallback'):
+            eventlet.tpool.execute(
+                conn.registerCloseCallback,
+                mox.IgnoreArg(),
+                mox.IgnoreArg())
         self.mox.ReplayAll()
 
         driver = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)

nova/virt/libvirt/driver.py

@@ -323,7 +323,6 @@ MIN_LIBVIRT_VERSION = (0, 9, 6)
 # When the above version matches/exceeds this version
 # delete it & corresponding code using it
 MIN_LIBVIRT_HOST_CPU_VERSION = (0, 9, 10)
-MIN_LIBVIRT_CLOSE_CALLBACK_VERSION = (1, 0, 1)
 MIN_LIBVIRT_DEVICE_CALLBACK_VERSION = (1, 1, 1)
 # Live snapshot requirements
 REQ_HYPERVISOR_LIVESNAPSHOT = "QEMU"
@@ -634,7 +633,7 @@ class LibvirtDriver(driver.ComputeDriver):
         self._wrapped_conn = wrapped_conn
 
         try:
-            LOG.debug(_("Registering for lifecycle events %s") % str(self))
+            LOG.debug(_("Registering for lifecycle events %s"), self)
             wrapped_conn.domainEventRegisterAny(
                 None,
                 libvirt.VIR_DOMAIN_EVENT_ID_LIFECYCLE,
@@ -644,17 +643,23 @@ class LibvirtDriver(driver.ComputeDriver):
             LOG.warn(_("URI %(uri)s does not support events: %(error)s"),
                      {'uri': self.uri(), 'error': e})
 
-        if self._has_min_version(wrapped_conn,
+        try:
-                                 MIN_LIBVIRT_CLOSE_CALLBACK_VERSION):
+            LOG.debug(_("Registering for connection events: %s") %
-            try:
+                      str(self))
-                LOG.debug(_("Registering for connection events: %s") %
+            wrapped_conn.registerCloseCallback(self._close_callback, None)
-                          str(self))
+        except (TypeError, AttributeError) as e:
-                wrapped_conn.registerCloseCallback(
+            # NOTE: The registerCloseCallback of python-libvirt 1.0.1+
-                        self._close_callback, None)
+            # is defined with 3 arguments, and the above registerClose-
-            except libvirt.libvirtError as e:
+            # Callback succeeds. However, the one of python-libvirt 1.0.0
-                LOG.warn(_("URI %(uri)s does not support connection"
+            # is defined with 4 arguments and TypeError happens here.
-                         " events: %(error)s"),
+            # Then python-libvirt 0.9 does not define a method register-
-                         {'uri': self.uri(), 'error': e})
+            # CloseCallback.
+            LOG.debug(_("The version of python-libvirt does not support "
+                        "registerCloseCallback or is too old: %s"), e)
+        except libvirt.libvirtError as e:
+            LOG.warn(_("URI %(uri)s does not support connection"
+                       " events: %(error)s"),
+                     {'uri': self.uri(), 'error': e})
 
         return wrapped_conn