Hyper-V: Fix missing WMI namespace issue on Windows 2008 R2

The Hyper-V driver uses the Microsoft\Windows\SMB WMI namespace
in order to handle SMB shares. The issue is that this namespace is
not available on Windows versions prior to Windows Server 2012.

For this reason, the Hyper-V driver fails to initialize on Windows
Server 2008 R2.

This patch fixes the issue by properly handling the PathUtils
initialization.

Closes-Bug: #1463044
Change-Id: Ia99576589af6049ee07337c631ed7d5d6cf602d9
(cherry picked from commit 0625df9956)

nova/tests/unit/virt/hyperv/test_base.py

@@ -23,7 +23,9 @@ class HyperVBaseTestCase(test.NoDBTestCase):
     def setUp(self):
         super(HyperVBaseTestCase, self).setUp()
 
-        wmi_patcher = mock.patch('__builtin__.wmi', create=True)
+        self._mock_wmi = mock.MagicMock()
+        wmi_patcher = mock.patch('__builtin__.wmi', create=True,
+                                 new=self._mock_wmi)
         platform_patcher = mock.patch('sys.platform', 'win32')
 
         platform_patcher.start()

nova/tests/unit/virt/hyperv/test_pathutils.py

@@ -32,6 +32,26 @@ class PathUtilsTestCase(test_base.HyperVBaseTestCase):
 
         self._pathutils = pathutils.PathUtils()
 
+    def _test_smb_conn(self, smb_available=True):
+        self._mock_wmi.x_wmi = Exception
+        self._mock_wmi.WMI.side_effect = None if smb_available else Exception
+
+        self._pathutils._set_smb_conn()
+
+        if smb_available:
+            expected_conn = self._mock_wmi.WMI.return_value
+            self.assertEqual(expected_conn, self._pathutils._smb_conn)
+        else:
+            self.assertRaises(vmutils.HyperVException,
+                              getattr,
+                              self._pathutils, '_smb_conn')
+
+    def test_smb_conn_available(self):
+        self._test_smb_conn()
+
+    def test_smb_conn_unavailable(self):
+        self._test_smb_conn(smb_available=False)
+
     @mock.patch.object(pathutils.PathUtils, 'rename')
     @mock.patch.object(os.path, 'isfile')
     @mock.patch.object(os, 'listdir')

nova/virt/hyperv/pathutils.py

@@ -49,7 +49,24 @@ ERROR_INVALID_NAME = 123
 
 class PathUtils(object):
     def __init__(self):
-        self._smb_conn = wmi.WMI(moniker=r"root\Microsoft\Windows\SMB")
+        self._set_smb_conn()
+
+    @property
+    def _smb_conn(self):
+        if self._smb_conn_attr:
+            return self._smb_conn_attr
+        raise vmutils.HyperVException(_("The SMB WMI namespace is not "
+                                        "available on this OS version."))
+
+    def _set_smb_conn(self):
+        # The following namespace is not available prior to Windows
+        # Server 2012. utilsfactory is not used in order to avoid a
+        # circular dependency.
+        try:
+            self._smb_conn_attr = wmi.WMI(
+                moniker=r"root\Microsoft\Windows\SMB")
+        except wmi.x_wmi:
+            self._smb_conn_attr = None
 
     def open(self, path, mode):
         """Wrapper on __builtin__.open used to simplify unit testing."""