Update user_id length to match Keystone schema in volume_usage_cache

Update the maximum length to match the Keystone schema for maximum
user_id length in volume_usage_cache. In the case that Keystone were
to leverage the full varchar 64, there would potentially be data loss
and/or collision of user_ids across records.

This change originates from the conversation about increasing the
length of user_ids in Keystone:

http://lists.openstack.org/pipermail/openstack-dev/2014-February/028125.html

Even with the length not changing, it is important to ensure there is no
loss of data/resolution when relying on user_id to identify users uniquely.

Closes-Bug: #1226171
Change-Id: I05a5644a29d6e2432311c2ee5331970d5e8b0683

3 files changed, 40 insertions, 1 deletions

diff --git a/nova/db/sqlalchemy/migrate_repo/versions/244_increase_user_id_length_volume_usage_cache.py b/nova/db/sqlalchemy/migrate_repo/versions/244_increase_user_id_length_volume_usage_cache.py
new file mode 100644
index 0000000000..079003d733
--- /dev/null
+++ b/nova/db/sqlalchemy/migrate_repo/versions/244_increase_user_id_length_volume_usage_cache.py
@@ -0,0 +1,31 @@
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from sqlalchemy import MetaData, String, Table
+
+
+def upgrade(migrate_engine):
+    meta = MetaData(bind=migrate_engine)
+    table = Table('volume_usage_cache', meta, autoload=True)
+    col_resource = getattr(table.c, 'user_id')
+    # Match the maximum length of user_id in Keystone here instead of
+    # assuming explicitly a single UUID length.
+    col_resource.alter(type=String(64))
+
+
+def downgrade(migrate_engine):
+    meta = MetaData(bind=migrate_engine)
+    table = Table('volume_usage_cache', meta, autoload=True)
+    col_resource = getattr(table.c, 'user_id')
+    col_resource.alter(type=String(36))
diff --git a/nova/db/sqlalchemy/models.py b/nova/db/sqlalchemy/models.py
index 9f8043cc7c..ae4a1c3bb0 100644
--- a/nova/db/sqlalchemy/models.py
+++ b/nova/db/sqlalchemy/models.py
@@ -1144,7 +1144,7 @@ class VolumeUsage(BASE, NovaBase):
     volume_id = Column(String(36), nullable=False)
     instance_uuid = Column(String(36))
     project_id = Column(String(36))
-    user_id = Column(String(36))
+    user_id = Column(String(64))
     availability_zone = Column(String(255))
     tot_last_refreshed = Column(DateTime)
     tot_reads = Column(BigInteger, default=0)
diff --git a/nova/tests/db/test_migrations.py b/nova/tests/db/test_migrations.py
index 73531b986b..199aa5590c 100644
--- a/nova/tests/db/test_migrations.py
+++ b/nova/tests/db/test_migrations.py
@@ -695,6 +695,14 @@ class TestNovaMigrations(BaseWalkMigrationTestCase, CommonTestsMixIn):
         # confirm compute_node_stats exists
         db_utils.get_table(engine, 'compute_node_stats')
 
+    def _check_244(self, engine, data):
+        volume_usage_cache = db_utils.get_table(engine, 'volume_usage_cache')
+        self.assertEqual(64, volume_usage_cache.c.user_id.type.length)
+
+    def _post_downgrade_244(self, engine):
+        volume_usage_cache = db_utils.get_table(engine, 'volume_usage_cache')
+        self.assertEqual(36, volume_usage_cache.c.user_id.type.length)
+
 
 class TestBaremetalMigrations(BaseWalkMigrationTestCase, CommonTestsMixIn):
     """Test sqlalchemy-migrate migrations."""