From e5152a2ee383a3d92a7a5a0750ee4753ead55e35 Mon Sep 17 00:00:00 2001
From: Dan Smith <dansmith@redhat.com>
Date: Mon, 28 Aug 2017 10:56:59 -0700
Subject: [PATCH] Add uuid online migration for migrations

This adds an online data migration for nova-manage that will background-
process migrations in the database to have a uuid.

Related to blueprint migration-allocations

Change-Id: I5b4b235b88367c361d38371d430d67ff583a906c
---
 nova/cmd/manage.py                |  3 +++
 nova/db/sqlalchemy/api.py         | 19 ++++++++++++++++++
 nova/tests/unit/db/test_db_api.py | 32 +++++++++++++++++++++++++++++++
 3 files changed, 54 insertions(+)

diff --git a/nova/cmd/manage.py b/nova/cmd/manage.py
index 89494bcf3b..b46fa368c0 100644
--- a/nova/cmd/manage.py
+++ b/nova/cmd/manage.py
@@ -82,6 +82,7 @@ from nova import config
 from nova import context
 from nova import db
 from nova.db import migration
+from nova.db.sqlalchemy import api as sa_db
 from nova import exception
 from nova.i18n import _
 from nova import objects
@@ -666,6 +667,8 @@ class DbCommands(object):
         quotas_obj.migrate_quota_limits_to_api_db,
         # Added in Pike
         quotas_obj.migrate_quota_classes_to_api_db,
+        # Added in Queens
+        sa_db.migration_migrate_to_uuid,
     )
 
     def __init__(self):
diff --git a/nova/db/sqlalchemy/api.py b/nova/db/sqlalchemy/api.py
index afe1b80e40..4e69506c58 100644
--- a/nova/db/sqlalchemy/api.py
+++ b/nova/db/sqlalchemy/api.py
@@ -4821,6 +4821,25 @@ def migration_get_all_by_filters(context, filters):
     return query.all()
 
 
+@pick_context_manager_writer
+def migration_migrate_to_uuid(context, count):
+    # Avoid circular import
+    from nova import objects
+
+    db_migrations = model_query(context, models.Migration).filter_by(
+        uuid=None).limit(count).all()
+
+    done = 0
+    for db_migration in db_migrations:
+        mig = objects.Migration(context)
+        mig._from_db_object(context, mig, db_migration)
+        done += 1
+
+    # We don't have any situation where we can (detectably) not
+    # migrate a thing, so report anything that matched as "completed".
+    return done, done
+
+
 ##################
 
 
diff --git a/nova/tests/unit/db/test_db_api.py b/nova/tests/unit/db/test_db_api.py
index 75e3d1d183..7f33029a56 100644
--- a/nova/tests/unit/db/test_db_api.py
+++ b/nova/tests/unit/db/test_db_api.py
@@ -3827,6 +3827,38 @@ class ServiceTestCase(test.TestCase, ModelsObjectComparatorMixin):
         self.assertEqual(0, total)
         self.assertEqual(0, done)
 
+    def test_migration_migrate_to_uuid(self):
+        total, done = sqlalchemy_api.migration_migrate_to_uuid(self.ctxt, 10)
+        self.assertEqual(0, total)
+        self.assertEqual(0, done)
+
+        # Create two migrations, one with a uuid and one without.
+        db.migration_create(self.ctxt,
+                            dict(source_compute='src', source_node='srcnode',
+                                 dest_compute='dst', dest_node='dstnode',
+                                 status='running'))
+        db.migration_create(self.ctxt,
+                            dict(source_compute='src', source_node='srcnode',
+                                 dest_compute='dst', dest_node='dstnode',
+                                 status='running',
+                                 uuid=uuidsentinel.migration2))
+
+        # Now migrate them, we should find one and update one
+        total, done = sqlalchemy_api.migration_migrate_to_uuid(self.ctxt, 10)
+        self.assertEqual(1, total)
+        self.assertEqual(1, done)
+
+        # Get the migrations back to make sure the original uuid didn't change.
+        migrations = db.migration_get_all_by_filters(self.ctxt, {})
+        uuids = [m.uuid for m in migrations]
+        self.assertIn(uuidsentinel.migration2, uuids)
+        self.assertNotIn(None, uuids)
+
+        # Run the online migration again to see nothing was processed.
+        total, done = sqlalchemy_api.migration_migrate_to_uuid(self.ctxt, 10)
+        self.assertEqual(0, total)
+        self.assertEqual(0, done)
+
 
 class BaseInstanceTypeTestCase(test.TestCase, ModelsObjectComparatorMixin):
     def setUp(self):