Add database migration and model for consumers

Part of blueprint placement-project-user

Change-Id: Iecbe0eb5717afb0b13ca90d4868a3ca5f9e8902b

nova/db/sqlalchemy/api_migrations/migrate_repo/versions/043_placement_consumers.py

@@ -0,0 +1,44 @@
+#    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.
+"""Database migrations for consumers"""
+
+from migrate import UniqueConstraint
+from sqlalchemy import Column
+from sqlalchemy import DateTime
+from sqlalchemy import Index
+from sqlalchemy import Integer
+from sqlalchemy import MetaData
+from sqlalchemy import String
+from sqlalchemy import Table
+
+
+def upgrade(migrate_engine):
+    meta = MetaData()
+    meta.bind = migrate_engine
+
+    consumers = Table('consumers', meta,
+        Column('created_at', DateTime),
+        Column('updated_at', DateTime),
+        Column('id', Integer, primary_key=True, nullable=False,
+               autoincrement=True),
+        Column('uuid', String(length=36), nullable=False),
+        Column('project_id', String(length=255), nullable=False),
+        Column('user_id', String(length=255), nullable=False),
+        Index('consumers_project_id_uuid_idx', 'project_id', 'uuid'),
+        Index('consumers_project_id_user_id_uuid_idx', 'project_id', 'user_id',
+              'uuid'),
+        UniqueConstraint('uuid', name='uniq_consumers0uuid'),
+        mysql_engine='InnoDB',
+        mysql_charset='latin1'
+    )
+
+    consumers.create(checkfirst=True)

nova/db/sqlalchemy/api_models.py

@@ -582,3 +582,20 @@ class ResourceProviderTrait(API_BASE):
                                   ForeignKey('resource_providers.id'),
                                   primary_key=True,
                                   nullable=False)
+
+
+class Consumer(API_BASE):
+    """Represents a resource consumer."""
+
+    __tablename__ = 'consumers'
+    __table_args__ = (
+        Index('consumers_project_id_uuid_idx', 'project_id', 'uuid'),
+        Index('consumers_project_id_user_id_uuid_idx', 'project_id', 'user_id',
+              'uuid'),
+        schema.UniqueConstraint('uuid', name='uniq_consumers0uuid'),
+    )
+
+    id = Column(Integer, primary_key=True, nullable=False, autoincrement=True)
+    uuid = Column(String(36), nullable=False)
+    project_id = Column(String(255), nullable=False)
+    user_id = Column(String(255), nullable=False)