Increase the instance_info column size to LONGTEXT on MySQL/MariaDB

In MySQL, the maximum size of TEXT is 64KiB. The instance_info column
is defined as TEXT and can potentially hold big amount of data
(partly affected by cloud-init scripts for the node).

This patch-set resizes nodes.instance_info to LONGTEXT which allows up
to 4GiB of data to be stored in the column. This change is relevant only
to MySQL and does not affect PostgreSQL or any other DB flavor. The fix
also addresses the upgrade process of the column.

Change-Id: Ifb9a49d4258a559cf2175d902e9424a3f98065c5
Closes-Bug: #1596421

ironic/db/sqlalchemy/alembic/versions/e918ff30eb42_resize_column_nodes_instance_info.py

@@ -0,0 +1,32 @@
+#    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.
+
+"""resize column nodes instance_info
+
+Revision ID: e918ff30eb42
+Revises: b4130a7fc904
+Create Date: 2016-06-28 13:30:19.396203
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = 'e918ff30eb42'
+down_revision = 'b4130a7fc904'
+
+from alembic import op
+from oslo_db.sqlalchemy import types as db_types
+
+
+def upgrade():
+    op.alter_column('nodes', 'instance_info',
+                    existing_type=db_types.JsonEncodedDict.impl,
+                    type_=db_types.JsonEncodedDict(mysql_as_long=True).impl)

ironic/db/sqlalchemy/models.py

@@ -136,7 +136,7 @@ class Node(Base):
     target_provision_state = Column(String(15), nullable=True)
     provision_updated_at = Column(DateTime, nullable=True)
     last_error = Column(Text, nullable=True)
-    instance_info = Column(db_types.JsonEncodedDict)
+    instance_info = Column(db_types.JsonEncodedDict(mysql_as_long=True))
     properties = Column(db_types.JsonEncodedDict)
     driver = Column(String(255))
     driver_info = Column(db_types.JsonEncodedDict)

ironic/tests/unit/db/sqlalchemy/test_migrations.py

@@ -698,6 +698,44 @@ class TestMigrationsMySQL(MigrationCheckersMixin,
                           test_base.BaseTestCase):
     FIXTURE = test_fixtures.MySQLOpportunisticFixture
 
+    def _pre_upgrade_e918ff30eb42(self, engine):
+
+        nodes = db_utils.get_table(engine, 'nodes')
+
+        # this should always fail pre-upgrade
+        mediumtext = 'a' * (pow(2, 16) + 1)
+        uuid = uuidutils.generate_uuid()
+        expected_to_fail_data = {'uuid': uuid, 'instance_info': mediumtext}
+        self.assertRaises(db_exc.DBError,
+                          nodes.insert().execute, expected_to_fail_data)
+
+        # this should always work pre-upgrade
+        text = 'a' * (pow(2, 16) - 1)
+        uuid = uuidutils.generate_uuid()
+        valid_pre_upgrade_data = {'uuid': uuid, 'instance_info': text}
+        nodes.insert().execute(valid_pre_upgrade_data)
+
+        return valid_pre_upgrade_data
+
+    def _check_e918ff30eb42(self, engine, data):
+
+        nodes = db_utils.get_table(engine, 'nodes')
+
+        # check that the data for the successful pre-upgrade
+        # entry didn't change
+        node = nodes.select(nodes.c.uuid == data['uuid']).execute().first()
+        self.assertIsNotNone(node)
+        self.assertEqual(data['instance_info'], node['instance_info'])
+
+        # now this should pass post-upgrade
+        test = 'b' * (pow(2, 16) + 1)
+        uuid = uuidutils.generate_uuid()
+        data = {'uuid': uuid, 'instance_info': test}
+        nodes.insert().execute(data)
+
+        node = nodes.select(nodes.c.uuid == uuid).execute().first()
+        self.assertEqual(test, node['instance_info'])
+
 
 class TestMigrationsPostgreSQL(MigrationCheckersMixin,
                                WalkVersionsMixin,

releasenotes/notes/bug-1596421-0cb8f59073f56240.yaml

@@ -0,0 +1,9 @@
+---
+upgrade:
+  - Extends the ``instance_info`` column in the nodes table for MySQL/MariaDB
+    from up to 64KiB to up to 4GiB (type is changed from TEXT to LONGTEXT).
+    This upgrade will not be executed on PostgreSQL as its TEXT is unlimited.
+fixes:
+  - The config drive passed to the node can now contain more than 64KiB
+    in case of MySQL/MariaDB. For more details see `bug 1596421
+    <https://bugs.launchpad.net/ironic/+bug/1596421>`_.