Fix block-device-mapping when volume_size is empty

The Nova API responds with an validation error when a bdm is submitted
containing an empty volume_size. So instead omit that attribute when it
is empty.

Change-Id: Iba905fca8c440a03e828c20922f3b813bba3fa3a
Closes-Bug: 1677236

openstackclient/compute/v2/server.py

@@ -544,7 +544,7 @@ class CreateServer(command.ShowOne):
                     else:
                         mapping['source_type'] = 'volume'
                     mapping['destination_type'] = 'volume'
-                    if len(dev_map) > 2:
+                    if len(dev_map) > 2 and dev_map[2]:
                         mapping['volume_size'] = dev_map[2]
                     if len(dev_map) > 3:
                         mapping['delete_on_termination'] = dev_map[3]

openstackclient/tests/unit/compute/v2/test_server.py

@@ -817,8 +817,7 @@ class TestServerCreate(TestServer):
                 'uuid': real_volume_mapping.split(':', 1)[0],
                 'destination_type': 'volume',
                 'source_type': 'volume',
-                'delete_on_termination': '0',
-                'volume_size': ''
+                'delete_on_termination': '0'
             }],
             nics=[],
             scheduler_hints={},

releasenotes/notes/bug-1677236-7de9d11c3f0fb5ed.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fix creating a server with a block-device-mapping when volume_size
+    is empty.
+    [Bug `1677236 <https://bugs.launchpad.net/bugs/1652827>`_]