db: add missing primary key in spares_pool table

In commit a205ab3ebe a new model
spares_pool has been introduced but the definition introduced by
0b468090e6 was missing the primary key.

In this commit we fixed the definition and add an update script for
already deployed env.

Note: without the PK this creates an error when Running Percona with
pxc_strict_mode == ENFORCING

Story: 2005531
Task: 30658
Change-Id: If70e5df5aea008e8998eaad912ba85dfb6bda77a
Signed-off-by: Sahid Orentino Ferdjaoui <sahid.ferdjaoui@canonical.com>

octavia/db/migration/alembic_migrations/versions/392fb85b4419_add_primary_key_to_spares_pool.py

@@ -0,0 +1,47 @@
+#    Copyright 2016 Rackspace
+#
+#    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.
+
+"""add primary key to spares_pool
+
+Revision ID: 392fb85b4419
+Revises: 46d914b2a5e5
+Create Date: 2019-04-30 09:58:54.159823
+
+"""
+
+from alembic import op
+from sqlalchemy.engine import reflection
+
+from oslo_log import log as logging
+
+
+# revision identifiers, used by Alembic.
+revision = '392fb85b4419'
+down_revision = '46d914b2a5e5'
+
+LOG = logging.getLogger(__name__)
+
+
+def upgrade():
+    bind = op.get_bind()
+    inspector = reflection.Inspector.from_engine(bind.engine)
+    pk = inspector.get_pk_constraint('spares_pool')
+    if not pk['constrained_columns']:
+        op.create_primary_key(
+            u'pk_spares_pool', u'spares_pool', [u'updated_at'])
+    else:
+        # Revision '46d914b2a5e5' has been updated to create the
+        # missing PK. Depending whether the env is already deployed or
+        # not we may or not have to add the primary key.
+        LOG.info("The primary key in spares_pool already exists, continuing.")

octavia/db/migration/alembic_migrations/versions/6ffc710674ef_spares_pool_table.py

@@ -31,5 +31,5 @@ down_revision = '7432f1d4ea83'
 def upgrade():
     op.create_table(
         u'spares_pool',
-        sa.Column(u'updated_at', sa.DateTime(), nullable=True,
+        sa.Column(u'updated_at', sa.DateTime(), primary_key=True,
                   server_default=sa.func.current_timestamp()))