Merge lp:~mpontillo/maas/bug-1460189-python-vmomi-import into lp:~maas-committers/maas/trunk

[Mike Pontillo]

Import python-pyvmomi using import_module() just before use, so that there is no need to restart maas-clusterd after installing python-pyvmomi.

[Gavin Panella (allenap)]

Good stuff, but as ever I've blathered on a bit.

review: Approve

[Mike Pontillo (mpontillo)]

Some replies below. Thanks for the review!

=== modified file 'src/provisioningserver/drivers/hardware/tests/test_vmware.py'
--- src/provisioningserver/drivers/hardware/tests/test_vmware.py	2015-05-20 19:23:53 +0000
+++ src/provisioningserver/drivers/hardware/tests/test_vmware.py	2015-06-01 23:10:51 +0000
@@ -40,14 +40,6 @@
 from twisted.internet.threads import deferToThread
 
 
-try:
-    import pyVmomi
-    import pyVim.connect as vmomi_api
-except ImportError:
-    pyVmomi = None
-    vmomi_api = None
-
-
 class FakeVmomiVMSummaryConfig(object):
     def __init__(self, name, has_instance_uuid=None, has_uuid=None):
         self.name = name
@@ -230,7 +222,7 @@
 
     def setUp(self):
         super(TestVMwarePyvmomi, self).setUp()
-        if vmomi_api is None:
+        if vmware.try_pyvmomi_import() is False:
             self.skipTest('cannot test VMware without python-pyvmomi')
 
     def test_api_connection(self):

=== modified file 'src/provisioningserver/drivers/hardware/vmware.py'
--- src/provisioningserver/drivers/hardware/vmware.py	2015-05-20 07:02:32 +0000
+++ src/provisioningserver/drivers/hardware/vmware.py	2015-06-01 23:10:51 +0000
@@ -18,6 +18,7 @@
 
 from abc import abstractmethod
 from collections import OrderedDict
+from importlib import import_module
 import traceback
 from urllib import unquote
 
@@ -29,17 +30,31 @@
 from provisioningserver.utils.twisted import synchronous
 
 
-try:
-    import pyVmomi
-    from pyVmomi import vim
-    import pyVim.connect as vmomi_api
-except ImportError:
-    pyVmomi = None
-    vmomi_api = None
+vmomi_api = None
+vim = None
 
 maaslog = get_maas_logger("drivers.vmware")
 
 
+def try_pyvmomi_import():
+    """Attempt to import the pyVmomi API. This API is provided by the
+    python-pyvmomi package; if it doesn't work out, we need to notify
+    the user so they can install it.
+    """
+    global vim
+    global vmomi_api
+    try:
+        if vim is None:
+            vim_module = import_module('pyVmomi')
+            vim = getattr(vim_module, 'vim')
+        if vmomi_api is None:
+            vmomi_api = import_module('pyVim.connect')
+    except ImportError:
+        return False
+    else:
+        return True
+
+
 class VMwareAPIException(Exception):
     """Failure talking to the VMware API."""
 
@@ -321,7 +336,7 @@
 
 def _get_vmware_api(
         host, username, password, port=None, protocol=None):
-    if pyVmomi is not None:
+    if try_pyvmomi_import():
         # Attempt to detect the best available VMware API
         return VMwarePyvmomiAPI(
             host, username, password, port=port, protocol=protocol)