compute: Stop silently ignore --(no-)disk-overcommit

These options are not supported from Nova API microversion 2.25 and
above. This can be a source of confusion. Start warning, with an eye on
erroring out in the future.

Change-Id: I53f27eb3e3c1a84d0d77a1672c008d0e8bb8536f
Signed-off-by: Stephen Finucane <sfinucan@redhat.com>

openstackclient/compute/v2/server.py

@@ -2519,7 +2519,10 @@ revert to release the new server and restart the old one.""")
             '--disk-overcommit',
             action='store_true',
             default=False,
-            help=_('Allow disk over-commit on the destination host'),
+            help=_(
+                'Allow disk over-commit on the destination host'
+                '(supported with --os-compute-api-version 2.24 or below)'
+            ),
         )
         disk_group.add_argument(
             '--no-disk-overcommit',
@@ -2528,6 +2531,7 @@ revert to release the new server and restart the old one.""")
             default=False,
             help=_(
                 'Do not over-commit disk on the destination host (default)'
+                '(supported with --os-compute-api-version 2.24 or below)'
             ),
         )
         parser.add_argument(
@@ -2603,6 +2607,15 @@ revert to release the new server and restart the old one.""")
 
             if compute_client.api_version < api_versions.APIVersion('2.25'):
                 kwargs['disk_over_commit'] = parsed_args.disk_overcommit
+            elif parsed_args.disk_overcommit is not None:
+                # TODO(stephenfin): Raise an error here in OSC 7.0
+                msg = _(
+                    'The --disk-overcommit and --no-disk-overcommit '
+                    'options are only supported by '
+                    '--os-compute-api-version 2.24 or below; this will '
+                    'be an error in a future release'
+                )
+                self.log.warning(msg)
 
             server.live_migrate(**kwargs)
         else:

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

@@ -4832,6 +4832,40 @@ class TestServerMigrate(TestServer):
         self.assertNotCalled(self.servers_mock.migrate)
         self.assertIsNone(result)
 
+    def test_server_live_migrate_with_disk_overcommit_post_v224(self):
+        arglist = [
+            '--live-migration',
+            '--disk-overcommit',
+            self.server.id,
+        ]
+        verifylist = [
+            ('live', None),
+            ('live_migration', True),
+            ('block_migration', None),
+            ('disk_overcommit', True),
+            ('wait', False),
+        ]
+        parsed_args = self.check_parser(self.cmd, arglist, verifylist)
+
+        self.app.client_manager.compute.api_version = \
+            api_versions.APIVersion('2.25')
+
+        with mock.patch.object(self.cmd.log, 'warning') as mock_warning:
+            result = self.cmd.take_action(parsed_args)
+
+        self.servers_mock.get.assert_called_with(self.server.id)
+        # There should be no 'disk_over_commit' value present
+        self.server.live_migrate.assert_called_with(
+            block_migration='auto',
+            host=None)
+        self.assertNotCalled(self.servers_mock.migrate)
+        self.assertIsNone(result)
+        # A warning should have been logged for using --disk-overcommit.
+        mock_warning.assert_called_once()
+        self.assertIn(
+            'The --disk-overcommit and --no-disk-overcommit options ',
+            str(mock_warning.call_args[0][0]))
+
     def test_server_live_migrate_with_false_value_options(self):
         arglist = [
             '--live', 'fakehost', '--no-disk-overcommit',

releasenotes/notes/warn-on-disk-overcommit-087ae46f12d74693.yaml

@@ -0,0 +1,9 @@
+---
+upgrade:
+  - |
+    A warning will now be emitted when using the ``--disk-overcommit``
+    or ``--no-disk-overcommit`` flags of the ``server migrate`` command on
+    Compute API microversion 2.25 or greater. This feature is only supported
+    before this microversion and previously the flag was silently ignored on
+    newer microversions. This warning will become an error in a future
+    release.