Add flavor migration routine

This adds a function and nova-manage command that moves flavors from
the main DB to the API DB. Note that it also includes an online
migration that doesn't actually change any data, but only resets the
autoincrement value for postgres, if necessary. This is not put
into the main migration simply because that one may run small chunks
of flavors and won't know what the real maximum is.

Related to blueprint flavor-cell-api

Depends-On: Ibc02acc60b1023039f2613f8949b95d55169fd30
Change-Id: I4ac31d6ff96595ea31d96d8604f690aa964d5709

nova/tests/functional/db/test_flavor.py

@@ -16,6 +16,7 @@ from nova.db.sqlalchemy import api as db_api
 from nova.db.sqlalchemy import api_models
 from nova import exception
 from nova import objects
+from nova.objects import flavor as flavor_obj
 from nova import test
 from nova.tests import fixtures
 
@@ -229,3 +230,28 @@ class FlavorObjectTestCase(test.NoDBTestCase):
         flavor.create()
         self.assertRaises(exception.MarkerNotFound,
                           self._test_get_all, 2, marker='noflavoratall')
+
+
+class FlavorMigrationTestCase(test.NoDBTestCase):
+    def setUp(self):
+        super(FlavorMigrationTestCase, self).setUp()
+        self.useFixture(fixtures.Database())
+        self.useFixture(fixtures.Database(database='api'))
+        self.context = context.get_admin_context()
+
+    def test_migration(self):
+        main_flavors = len(db.flavor_get_all(self.context))
+        match, done = flavor_obj.migrate_flavors(self.context, 50)
+        self.assertEqual(main_flavors, match)
+        self.assertEqual(main_flavors, done)
+        self.assertEqual(0, len(db.flavor_get_all(self.context)))
+        self.assertEqual(main_flavors,
+                         len(objects.FlavorList.get_all(self.context)))
+
+    def test_migrate_flavor_reset_autoincrement(self):
+        # NOTE(danms): Not much we can do here other than just make
+        # sure that the non-postgres case does not explode.
+        match, done = flavor_obj.migrate_flavor_reset_autoincrement(
+            self.context, 0)
+        self.assertEqual(0, match)
+        self.assertEqual(0, done)