Drop the container_actions table foreign key

container_actions.container_uuid is a foreign key of
container.uuid. When user delete a container, zun will delete the
data of the container from database. With this foreign key contrain,
it will generate error in deleting container data.

This commit remove the container_actions table's foreign key. Using
orm.relationship to join container_actions.container_uuid and
container.uuid.

Change-Id: Iac25adc69495826e6d5b0109eb729a0387e63c0b

zun/db/sqlalchemy/alembic/versions/8b0082d9e7c1_drop_foreign_key_of_container_actions.py

@@ -0,0 +1,43 @@
+#    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.
+
+"""drop foreign key of container_actions container_uuid
+
+Revision ID: 8b0082d9e7c1
+Revises: b6bfca998431
+Create Date: 2017-12-14 15:32:38.520594
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '8b0082d9e7c1'
+down_revision = 'b6bfca998431'
+branch_labels = None
+depends_on = None
+
+from alembic import op
+from sqlalchemy.engine.reflection import Inspector as insp
+
+CONTAINER_ACTIONS = 'container_actions'
+CONTAINER = 'container'
+
+
+def upgrade():
+    bind = op.get_bind()
+
+    inspector = insp.from_engine(bind)
+    foreign_keys = inspector.get_foreign_keys(CONTAINER_ACTIONS)
+
+    for foreign_key in foreign_keys:
+        if foreign_key.get('referred_table') == CONTAINER:
+            op.drop_constraint(foreign_key.get('name'), CONTAINER_ACTIONS,
+                               type_="foreignkey")

zun/db/sqlalchemy/models.py

@@ -427,6 +427,11 @@ class ContainerAction(Base):
     start_time = Column(DateTime, default=timeutils.utcnow)
     finish_time = Column(DateTime)
     message = Column(String(255))
+    container = orm.relationship(
+        "Container", backref="container_actions",
+        foreign_keys=container_uuid,
+        primaryjoin='and_(ContainerAction.container_uuid == Container.uuid)'
+    )
 
 
 class ContainerActionEvent(Base):