Add an update_cell command to nova-manage

In case a cell record was incorrectly created, or needs to be updated
to point to a new database or mq endpoint, we need a way for users to
be able to update a CellMapping record. Since deleting and re-creating
is definitely not an option, this patch adds an update_cell which
allows updating the mutable fields if necessary.

Change-Id: I75ddfa458a6fb650f1098505193398984f2be596

doc/source/man/nova-manage.rst

@@ -163,6 +163,17 @@ Nova Cells v2
     found, 2 if host mappings were found for the cell (cell not empty), and
     3 if there are instances mapped to the cell (cell not empty).
 
+``nova-manage cell_v2 update_cell --cell_uuid <cell_uuid> [--name <cell_name>] [--transport-url <transport_url>] [--database_connection <database_connection>]``
+
+    Updates the properties of a cell by the given uuid. If the cell is not
+    found by uuid, this command will return an exit code of 1. If the
+    properties cannot be set, this will return 2. Otherwise, the exit code
+    will be 0.
+
+    NOTE: Updating the transport_url or database_connection fields on
+    a running system will NOT result in all nodes immediately using the
+    new values. Use caution when changing these values.
+
 Nova Logs
 ~~~~~~~~~
 

nova/cmd/manage.py

@@ -1496,6 +1496,49 @@ class CellV2Commands(object):
         cell_mapping.destroy()
         return 0
 
+    @args('--cell_uuid', metavar='<cell_uuid>', dest='cell_uuid',
+          required=True, help=_('The uuid of the cell to update.'))
+    @args('--name', metavar='<name>', dest='name',
+          help=_('Set the cell name.'))
+    @args('--transport-url', metavar='<transport>', dest='transport_url',
+          help=_('Set the cell transport_url. NOTE that running nodes '
+                 'will not see the change until restart!'))
+    @args('--database_connection', metavar='<database>', dest='db_connection',
+          help=_('Set the cell database_connection. NOTE that running nodes '
+                 'will not see the change until restart!'))
+    def update_cell(self, cell_uuid, name, transport_url, db_connection):
+        """Updates the properties of a cell by the given uuid.
+
+        If the cell is not found by uuid, this command will return an exit
+        code of 1. If the properties cannot be set, this will return 2.
+        Otherwise, the exit code will be 0.
+
+        NOTE: Updating the transport_url or database_connection fields on
+        a running system will NOT result in all nodes immediately using the
+        new values. Use caution when changing these values.
+        """
+        ctxt = context.get_admin_context()
+        try:
+            cell_mapping = objects.CellMapping.get_by_uuid(ctxt, cell_uuid)
+        except exception.CellMappingNotFound:
+            print(_('Cell with uuid %s was not found.') % cell_uuid)
+            return 1
+
+        if name:
+            cell_mapping.name = name
+        if transport_url:
+            cell_mapping.transport_url = transport_url
+        if db_connection:
+            cell_mapping.database_connection = db_connection
+
+        try:
+            cell_mapping.save()
+        except Exception as e:
+            print(_('Unable to update CellMapping: %s') % e)
+            return 2
+
+        return 0
+
 
 CATEGORIES = {
     'account': AccountCommands,

nova/tests/unit/test_nova_manage.py

@@ -1532,6 +1532,38 @@ class CellV2CommandsTestCase(test.NoDBTestCase):
         output = self.output.getvalue().strip()
         self.assertEqual('', output)
 
+    def test_update_cell_not_found(self):
+        self.assertEqual(1, self.commands.update_cell(
+            uuidsentinel.cell1, 'foo', 'fake://new', 'fake:///new'))
+        self.assertIn('not found', self.output.getvalue())
+
+    def test_update_cell_failed(self):
+        ctxt = context.get_admin_context()
+        objects.CellMapping(context=ctxt, uuid=uuidsentinel.cell1,
+                            name='cell1',
+                            transport_url='fake://mq',
+                            database_connection='fake:///db').create()
+        with mock.patch('nova.objects.CellMapping.save') as mock_save:
+            mock_save.side_effect = Exception
+            self.assertEqual(2, self.commands.update_cell(
+                uuidsentinel.cell1, 'foo', 'fake://new', 'fake:///new'))
+        self.assertIn('Unable to update', self.output.getvalue())
+
+    def test_update_cell_success(self):
+        ctxt = context.get_admin_context()
+        objects.CellMapping(context=ctxt, uuid=uuidsentinel.cell1,
+                            name='cell1',
+                            transport_url='fake://mq',
+                            database_connection='fake:///db').create()
+        self.assertEqual(0, self.commands.update_cell(
+            uuidsentinel.cell1, 'foo', 'fake://new', 'fake:///new'))
+        cm = objects.CellMapping.get_by_uuid(ctxt, uuidsentinel.cell1)
+        self.assertEqual('foo', cm.name)
+        self.assertEqual('fake://new', cm.transport_url)
+        self.assertEqual('fake:///new', cm.database_connection)
+        output = self.output.getvalue().strip()
+        self.assertEqual('', output)
+
 
 class TestNovaManageMain(test.NoDBTestCase):
     """Tests the nova-manage:main() setup code."""