Empty option value maybe cause Unity driver failed to initialize

If the value of list type option is empty, Unity driver may failed to
initialize.

Example:
unity_io_ports=
unity_storage_pool_names=

Change-Id: Ib5850d984bfd3651d308f448993251e9ec5a9460
Closes-bug: #1775518
(cherry picked from commit 2ecfd6144b)
(cherry picked from commit c7f9d29e17)

cinder/tests/unit/volume/drivers/dell_emc/unity/test_driver.py

@@ -129,7 +129,8 @@ class UnityDriverTest(unittest.TestCase):
     def test_default_initialize(self):
         config = conf.Configuration(None)
         iscsi_driver = driver.UnityDriver(configuration=config)
-        self.assertIsNone(config.unity_storage_pool_names)
+        self.assertListEqual([], config.unity_storage_pool_names)
+        self.assertListEqual([], config.unity_io_ports)
         self.assertTrue(config.san_thin_provision)
         self.assertEqual('', config.san_ip)
         self.assertEqual('admin', config.san_login)

cinder/tests/unit/volume/drivers/dell_emc/unity/test_utils.py

@@ -254,3 +254,24 @@ class UnityUtilsTest(unittest.TestCase):
         ret = utils.get_backend_qos_specs(volume)
         expected = {'maxBWS': 2, 'id': 'max_2_mbps', 'maxIOPS': None}
         self.assertEqual(expected, ret)
+
+    def test_remove_empty(self):
+        option = mock.Mock()
+        value_list = [' pool1', 'pool2 ', '     pool3  ']
+        ret = utils.remove_empty(option, value_list)
+        expected = ['pool1', 'pool2', 'pool3']
+        self.assertListEqual(expected, ret)
+
+    def test_remove_empty_none(self):
+        option = mock.Mock()
+        value_list = None
+        ret = utils.remove_empty(option, value_list)
+        expected = None
+        self.assertEqual(expected, ret)
+
+    def test_remove_empty_empty_list(self):
+        option = mock.Mock()
+        value_list = []
+        ret = utils.remove_empty(option, value_list)
+        expected = None
+        self.assertEqual(expected, ret)

cinder/volume/drivers/dell_emc/unity/driver.py

@@ -31,11 +31,11 @@ CONF = cfg.CONF
 
 UNITY_OPTS = [
     cfg.ListOpt('unity_storage_pool_names',
-                default=None,
+                default=[],
                 help='A comma-separated list of storage pool names to be '
                 'used.'),
     cfg.ListOpt('unity_io_ports',
-                default=None,
+                default=[],
                 help='A comma-separated list of iSCSI or FC ports to be used. '
                      'Each port can be Unix-style glob expressions.'),
     cfg.BoolOpt('remove_empty_host',
@@ -63,9 +63,12 @@ class UnityDriver(driver.ManageableVD,
         2.0.2 - Support remove empty host
         2.0.3 - Cherry-pick the fix for 1773305 to return the targets which
                 connect to the logged-out initiators
+        2.0.4 - Fixes bug 1775518 to make sure driver succeed to initialize
+                even though the value of unity_io_ports and
+                unity_storage_pool_names are empty
     """
 
-    VERSION = '02.00.03'
+    VERSION = '02.00.04'
     VENDOR = 'Dell EMC'
     # ThirdPartySystems wiki page
     CI_WIKI_NAME = "EMC_UNITY_CI"

cinder/volume/drivers/dell_emc/unity/utils.py

@@ -270,12 +270,13 @@ def get_backend_qos_specs(volume):
 
 
 def remove_empty(option, value_list):
-    if value_list is not None:
+    if value_list:
         value_list = list(filter(None, map(str.strip, value_list)))
         if not value_list:
             raise exception.InvalidConfigurationValue(option=option,
                                                       value=value_list)
         return value_list
+    return None
 
 
 def match_any(full, patterns):

releasenotes/notes/bug-1775518-fix-unity-empty-list-issue-2d6b7c33aae1ffcc.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Dell EMC Unity: Fixes bug 1775518 to make sure driver succeed
+    to initialize even though the value of unity_io_ports and
+    unity_storage_pool_names are empty