Added alembic DB migration framework

This patch adds alembic DB migration framework required by
neutron-dynamic-routing repository for defining new data
models to realize BGP dynamic routing functionality in neutron.

Below changes are done as part of this patch-set:
 - Added new alembic migration framework.
 - PEP8 changes for alembic migration check.

Change-Id: I395ca9541bceda40bbc0c0870e58c18231ba44e9
Implements: blueprint bgp-spinout
Partial-Bug: #1560003

neutron_dynamic_routing/db/migration/README

@@ -0,0 +1,2 @@
+For details refer to:
+http://docs.openstack.org/developer/neutron-dynamic-routing/alembic_migration.html

neutron_dynamic_routing/db/migration/alembic_migrations/env.py

@@ -0,0 +1,88 @@
+#    Copyright 2016 Huawei Technologies India Pvt Limited.
+#
+#    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.
+
+from logging import config as logging_config
+
+from alembic import context
+from neutron.db import model_base
+from oslo_config import cfg
+from oslo_db.sqlalchemy import session
+import sqlalchemy as sa
+from sqlalchemy import event
+
+from neutron_dynamic_routing.db.migration.models import head  # noqa
+
+
+MYSQL_ENGINE = None
+DR_VERSION_TABLE = 'alembic_version_dr'
+config = context.config
+neutron_config = config.neutron_config
+logging_config.fileConfig(config.config_file_name)
+target_metadata = model_base.BASEV2.metadata
+
+
+def set_mysql_engine():
+    try:
+        mysql_engine = neutron_config.command.mysql_engine
+    except cfg.NoSuchOptError:
+        mysql_engine = None
+
+    global MYSQL_ENGINE
+    MYSQL_ENGINE = (mysql_engine or
+                    model_base.BASEV2.__table_args__['mysql_engine'])
+
+
+def run_migrations_offline():
+    set_mysql_engine()
+
+    kwargs = dict()
+    if neutron_config.database.connection:
+        kwargs['url'] = neutron_config.database.connection
+    else:
+        kwargs['dialect_name'] = neutron_config.database.engine
+    kwargs['version_table'] = DR_VERSION_TABLE
+    context.configure(**kwargs)
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+@event.listens_for(sa.Table, 'after_parent_attach')
+def set_storage_engine(target, parent):
+    if MYSQL_ENGINE:
+        target.kwargs['mysql_engine'] = MYSQL_ENGINE
+
+
+def run_migrations_online():
+    set_mysql_engine()
+    engine = session.create_engine(neutron_config.database.connection)
+
+    connection = engine.connect()
+    context.configure(
+        connection=connection,
+        target_metadata=target_metadata,
+        version_table=DR_VERSION_TABLE
+    )
+    try:
+        with context.begin_transaction():
+            context.run_migrations()
+    finally:
+        connection.close()
+        engine.dispose()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

neutron_dynamic_routing/db/migration/alembic_migrations/script.py.mako

@@ -0,0 +1,36 @@
+#    Copyright 2016 Huawei Technologies India Pvt Limited.
+#
+#    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.
+#
+
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision}
+Create Date: ${create_date}
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = ${repr(up_revision)}
+down_revision = ${repr(down_revision)}
+% if branch_labels:
+branch_labels = ${repr(branch_labels)}
+%endif
+
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+def upgrade():
+    ${upgrades if upgrades else "pass"}

neutron_dynamic_routing/db/migration/alembic_migrations/versions/CONTRACT_HEAD

@@ -0,0 +1 @@
+61cc795e43e8

neutron_dynamic_routing/db/migration/alembic_migrations/versions/EXPAND_HEAD

@@ -0,0 +1 @@
+f399fa0f5f25

neutron_dynamic_routing/db/migration/alembic_migrations/versions/newton/contract/61cc795e43e8_initial.py

@@ -0,0 +1,37 @@
+#    Copyright 2016 Huawei Technologies India Pvt Limited.
+#
+#    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.
+#
+
+"""initial
+
+Revision ID: 61cc795e43e8
+Revises: start_neutron_dynamic_routing
+Create Date: 2016-05-03 08:30:18.421995
+
+"""
+
+from neutron.db import migration
+from neutron.db.migration import cli
+
+# revision identifiers, used by Alembic.
+revision = '61cc795e43e8'
+down_revision = 'start_neutron_dynamic_routing'
+branch_labels = (cli.CONTRACT_BRANCH,)
+
+# milestone identifier, used by neutron-db-manage
+neutron_milestone = [migration.NEWTON]
+
+
+def upgrade():
+    pass

neutron_dynamic_routing/db/migration/alembic_migrations/versions/newton/expand/f399fa0f5f25_initial.py

@@ -0,0 +1,37 @@
+#    Copyright 2016 Huawei Technologies India Pvt Limited.
+#
+#    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.
+#
+
+"""initial
+
+Revision ID: f399fa0f5f25
+Revises: None
+Create Date: 2016-05-03 08:30:18.421995
+
+"""
+
+from neutron.db import migration
+from neutron.db.migration import cli
+
+# revision identifiers, used by Alembic.
+revision = 'f399fa0f5f25'
+down_revision = 'start_neutron_dynamic_routing'
+branch_labels = (cli.EXPAND_BRANCH,)
+
+# milestone identifier, used by neutron-db-manage
+neutron_milestone = [migration.NEWTON]
+
+
+def upgrade():
+    pass

neutron_dynamic_routing/db/migration/alembic_migrations/versions/start_neutron_dynamic_routing.py

@@ -0,0 +1,30 @@
+#    Copyright 2016 Huawei Technologies India Pvt Limited.
+#
+#    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.
+#
+
+"""start neutron-dynamic-routing chain
+
+Revision ID: start_neutron_dynamic_routing
+Revises: None
+Create Date: 2016-04-26 18:42:08.262632
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = 'start_neutron_dynamic_routing'
+down_revision = None
+
+
+def upgrade():
+    pass

neutron_dynamic_routing/db/migration/models/head.py

@@ -0,0 +1,19 @@
+#    Copyright 2016 Huawei Technologies India Pvt Limited.
+#
+#    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.
+
+from neutron.db import model_base
+
+
+def get_metadata():
+    return model_base.BASEV2.metadata

setup.cfg

@@ -24,6 +24,10 @@ packages =
 setup-hooks =
     pbr.hooks.setup_hook
 
+[entry_points]
+neutron.db.alembic_migrations =
+    neutron-dynamic-routing = neutron_dynamic_routing.db.migration:alembic_migrations
+
 [build_sphinx]
 all_files = 1
 build-dir = doc/build

tox.ini

@@ -24,7 +24,9 @@ install_command = {toxinidir}/tools/tox_install.sh unconstrained {opts} {package
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:pep8]
-commands = flake8
+commands =
+  flake8
+  neutron-db-manage --subproject neutron-dynamic-routing --database-connection sqlite:// check_migration
 
 [testenv:i18n]
 commands = python ./tools/check_i18n.py ./neutron-dynamic-routing ./tools/i18n_cfg.py