Add manage command for cell0.

Add a nova manage command to insert a cell mapping for cell0.

    nova-manage cell_v2 map_cell0

blueprint cells-cell0

Change-Id: Ia000e970d66d75374fd7e4e8b9137e0c10939c8e

nova/cmd/manage.py

@@ -68,6 +68,7 @@ import oslo_messaging as messaging
 from oslo_utils import importutils
 from oslo_utils import uuidutils
 import six
+import six.moves.urllib.parse as urlparse
 
 from nova.api.ec2 import ec2utils
 from nova import availability_zones
@@ -1114,6 +1115,46 @@ class CellCommands(object):
 class CellV2Commands(object):
     """Commands for managing cells v2."""
 
+    @args('--database_connection',
+          metavar='<database_connection>',
+          help='The database connection url for cell0. '
+               'This is optional. If not provided, a standard database '
+               'connection will be used based on the API database connection '
+               'from the Nova configuration.'
+         )
+    def map_cell0(self, database_connection=None):
+        """Create a cell mapping for cell0.
+
+        cell0 is used for instances that have not been scheduled to any cell.
+        This generally applies to instances that have encountered an error
+        before they have been scheduled.
+
+        This command creates a cell mapping for this special cell which
+        requires a database to store the instance data.
+        """
+        def cell0_default_connection():
+            # If no database connection is provided one is generated
+            # based on the API database connection url.
+            # The cell0 database will use the same database scheme and
+            # netloc as the API database, with a related path.
+            scheme, netloc, path, query, fragment = \
+                urlparse.urlsplit(CONF.api_database.connection)
+            root, ext = os.path.splitext(path)
+            path = root + "_cell0" + ext
+            return urlparse.urlunsplit((scheme, netloc, path, query,
+                                        fragment))
+
+        dbc = database_connection or cell0_default_connection()
+        ctxt = context.RequestContext()
+        # A transport url of 'none://' is provided for cell0. RPC should not
+        # be used to access cell0 objects. Cells transport switching will
+        # ignore any 'none' transport type.
+        cell_mapping = objects.CellMapping(
+                ctxt, uuid=objects.CellMapping.CELL0_UUID, name="cell0",
+                transport_url="none:///",
+                database_connection=dbc)
+        cell_mapping.create()
+
     @args('--cell_uuid', metavar='<cell_uuid>', required=True,
             help='Unmigrated instances will be mapped to the cell with the '
                  'uuid provided.')

nova/objects/cell_mapping.py

@@ -22,6 +22,8 @@ class CellMapping(base.NovaTimestampObject, base.NovaObject):
     # Version 1.0: Initial version
     VERSION = '1.0'
 
+    CELL0_UUID = '00000000-0000-0000-0000-000000000000'
+
     fields = {
         'id': fields.IntegerField(read_only=True),
         'uuid': fields.UUIDField(),

nova/tests/unit/test_nova_manage.py

@@ -21,6 +21,7 @@ import mock
 from oslo_utils import uuidutils
 
 from nova.cmd import manage
+from nova import conf
 from nova import context
 from nova import db
 from nova.db import migration
@@ -33,6 +34,8 @@ from nova.tests.unit import fake_instance
 from nova.tests.unit.objects import test_network
 from nova.tests.unit import test_flavors
 
+CONF = conf.CONF
+
 
 class FixedIpCommandsTestCase(test.TestCase):
     def setUp(self):
@@ -882,3 +885,26 @@ class CellV2CommandsTestCase(test.TestCase):
             inst_mapping = objects.InstanceMapping.get_by_instance_uuid(ctxt,
                     uuid)
             self.assertEqual(ctxt.project_id, inst_mapping.project_id)
+
+    def test_map_cell0(self):
+        ctxt = context.RequestContext()
+        database_connection = 'fake:/foobar//'
+        self.commands.map_cell0(database_connection)
+        cell_mapping = objects.CellMapping.get_by_uuid(ctxt,
+                objects.CellMapping.CELL0_UUID)
+        self.assertEqual('cell0', cell_mapping.name)
+        self.assertEqual('none:///', cell_mapping.transport_url)
+        self.assertEqual(database_connection, cell_mapping.database_connection)
+
+    def test_map_cell0_default_database(self):
+        CONF.set_default('connection',
+                         'fake://netloc/nova_api',
+                         group='api_database')
+        ctxt = context.RequestContext()
+        self.commands.map_cell0()
+        cell_mapping = objects.CellMapping.get_by_uuid(ctxt,
+                objects.CellMapping.CELL0_UUID)
+        self.assertEqual('cell0', cell_mapping.name)
+        self.assertEqual('none:///', cell_mapping.transport_url)
+        self.assertEqual('fake://netloc/nova_api_cell0',
+                         cell_mapping.database_connection)

releasenotes/notes/create-cell0-mapping-60a9229c223a7516.yaml

@@ -0,0 +1,7 @@
+---
+upgrade:
+  - |
+    A new nova-manage command 'nova-manage cell_v2 map_cell0' is
+    now available. Creates a cell mapping for cell0, which is used for
+    storing instances that cannot be scheduled to any cell. This command
+    only needs to be called when upgrading to CellsV2.