mark oslo.vmware as optional dependency

Driver-specific requirements are not hard requirements, since the
choice of drivers is up to the operator. The oslo.vmware module is
herein moved out of requirements.txt and instead listed as an optional
dependency using the extras functionality in setup.cfg.

A check is added to the vmdk driver to gracefully handle import errors
if the vmdk driver is used and oslo.vmware is not found.

Change-Id: I9b00edc38f0700304a1a164f0679a734f8701ebe
Closes-Bug: #1475739

cinder/volume/drivers/vmware/vmdk.py

@@ -32,11 +32,16 @@ from oslo_log import log as logging
 from oslo_utils import excutils
 from oslo_utils import units
 from oslo_utils import uuidutils
-from oslo_vmware import api
-from oslo_vmware import exceptions
-from oslo_vmware import image_transfer
-from oslo_vmware import pbm
-from oslo_vmware import vim_util
+try:
+    import oslo_vmware
+except ImportError:
+    oslo_vmware = None
+else:
+    from oslo_vmware import api
+    from oslo_vmware import exceptions
+    from oslo_vmware import image_transfer
+    from oslo_vmware import pbm
+    from oslo_vmware import vim_util
 import six
 
 from cinder import exception
@@ -268,6 +273,11 @@ class VMwareEsxVmdkDriver(driver.VolumeDriver):
         :param context: Context information
         """
 
+        if oslo_vmware is None:
+            msg = _("Missing 'oslo_vmware' python module, ensure the library"
+                    " is installed and available.")
+            raise exception.VolumeDriverException(message=msg)
+
         # Throw error if required parameters are not set.
         required_params = ['vmware_host_ip',
                            'vmware_host_username',

requirements.txt

@@ -50,5 +50,4 @@ stevedore>=1.5.0 # Apache-2.0
 suds-jurko>=0.6
 WebOb>=1.2.3
 oslo.i18n>=1.5.0 # Apache-2.0
-oslo.vmware>=1.16.0 # Apache-2.0
 os-brick>=0.3.2 # Apache-2.0

setup.cfg

@@ -25,6 +25,10 @@ setup-hooks =
 packages =
     cinder
 
+[extras]
+vmdk =
+  oslo.vmware>=1.16.0 # Apache-2.0
+
 [entry_points]
 cinder.scheduler.filters =
     AvailabilityZoneFilter = cinder.openstack.common.scheduler.filters.availability_zone_filter:AvailabilityZoneFilter

tox.ini

@@ -13,6 +13,7 @@ install_command = pip install {opts} {packages}
 
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
+       .[vmdk]
 
 # By default ostestr will set concurrency
 # to ncpu, to specify something else use