Fix spare amphora check and creation

This patch fixes an issue when the SparesPool table is empty that blocks
spare amphorae creation. It creates a new spares pool entry if the table
is empty.

Story 2005352
Task 30306

Change-Id: I0ce2778277640ee9e509c709bf8621b8b025d6d3

octavia/db/migration/alembic_migrations/versions/46d914b2a5e5_seed_the_spares_pool_table.py

@@ -0,0 +1,47 @@
+# Copyright 2019 Michael Johnson
+#
+#    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.
+
+"""Seed the spares_pool table
+
+Revision ID: 46d914b2a5e5
+Revises: 6ffc710674ef
+Create Date: 2019-04-03 14:03:25.596157
+
+"""
+
+
+import datetime
+
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision = '46d914b2a5e5'
+down_revision = '6ffc710674ef'
+
+
+def upgrade():
+    # Create temporary table for table data seeding
+    insert_table = sa.table(
+        u'spares_pool',
+        sa.column(u'updated_at', sa.DateTime),
+    )
+
+    # Note: The date/time doesn't matter, we just need to seed the table.
+    op.bulk_insert(
+        insert_table,
+        [
+            {'updated_at': datetime.datetime.now()}
+        ]
+    )

releasenotes/notes/fix-spare-amphora-check-and-creation-3adf939b45610155.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    Fixed an issue that prevents spare amphorae to be created.