Isolate placement database config

The placement database connection (which can use the same connection
string as the api database) needs to be managed from its own module so
that the nova db files are not imported as this eventually leads to
importing object-related and other code which the placement service does
not need.

The wsgi application is now responsible for initializing the database
configuration.

Fixtures and a number of tests are updated to reflected the new
location of the placement engine.

The original parse_args needed to import RPC and database related
modules that are not required in the placement context. A new
_parse_args method is added to wsgi.py which does the minimal required
work. Because we no longer use the central parse_args, the placement
db sync in nova/cmd/manager.py must make a manual configuration of the
context manager.

blueprint placement-extract

Change-Id: I2fff528060ec52a4a2e26a6484bdf18359b95f77

nova/api/openstack/placement/db_api.py

@@ -0,0 +1,40 @@
+#    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 context manager for placement database connection, kept in its
+own file so the nova db_api (which has cascading imports) is not imported.
+"""
+
+
+from oslo_db.sqlalchemy import enginefacade
+
+
+placement_context_manager = enginefacade.transaction_context()
+
+
+def _get_db_conf(conf_group, connection=None):
+    kw = dict(conf_group.items())
+    if connection is not None:
+        kw['connection'] = connection
+    return kw
+
+
+def configure(conf):
+    if conf.placement_database.connection is None:
+        placement_context_manager.configure(
+            **_get_db_conf(conf.api_database))
+    else:
+        placement_context_manager.configure(
+            **_get_db_conf(conf.placement_database))
+
+
+def get_placement_engine():
+    return placement_context_manager.get_legacy_facade().get_engine()

nova/api/openstack/placement/objects/consumer.py

@@ -15,10 +15,10 @@ from oslo_versionedobjects import base
 from oslo_versionedobjects import fields
 import sqlalchemy as sa
 
+from nova.api.openstack.placement import db_api
 from nova.api.openstack.placement import exception
 from nova.api.openstack.placement.objects import project as project_obj
 from nova.api.openstack.placement.objects import user as user_obj
-from nova.db.sqlalchemy import api as db_api
 from nova.db.sqlalchemy import api_models as models
 
 CONSUMER_TBL = models.Consumer.__table__

nova/api/openstack/placement/objects/project.py

@@ -16,8 +16,8 @@ from oslo_versionedobjects import base
 from oslo_versionedobjects import fields
 import sqlalchemy as sa
 
+from nova.api.openstack.placement import db_api
 from nova.api.openstack.placement import exception
-from nova.db.sqlalchemy import api as db_api
 from nova.db.sqlalchemy import api_models as models
 
 CONF = cfg.CONF

nova/api/openstack/placement/objects/resource_provider.py

@@ -37,11 +37,11 @@ from sqlalchemy import func
 from sqlalchemy import sql
 from sqlalchemy.sql import null
 
+from nova.api.openstack.placement import db_api
 from nova.api.openstack.placement import exception
 from nova.api.openstack.placement.objects import consumer as consumer_obj
 from nova.api.openstack.placement.objects import project as project_obj
 from nova.api.openstack.placement.objects import user as user_obj
-from nova.db.sqlalchemy import api as db_api
 from nova.db.sqlalchemy import api_models as models
 from nova.db.sqlalchemy import resource_class_cache as rc_cache
 from nova.i18n import _

nova/api/openstack/placement/objects/user.py

@@ -16,8 +16,8 @@ from oslo_versionedobjects import base
 from oslo_versionedobjects import fields
 import sqlalchemy as sa
 
+from nova.api.openstack.placement import db_api
 from nova.api.openstack.placement import exception
-from nova.db.sqlalchemy import api as db_api
 from nova.db.sqlalchemy import api_models as models
 
 CONF = cfg.CONF

nova/api/openstack/placement/wsgi.py

@@ -19,14 +19,24 @@ import os
 import os.path
 
 from oslo_log import log as logging
+from oslo_utils import importutils
+import pbr.version
 
+from nova.api.openstack.placement import db_api
 from nova.api.openstack.placement import deploy
+from nova.common import config
 from nova import conf
-from nova import config
+
+
+profiler = importutils.try_import('osprofiler.opts')
+
 
 CONFIG_FILE = 'nova.conf'
 
 
+version_info = pbr.version.VersionInfo('nova')
+
+
 def setup_logging(config):
     # Any dependent libraries that have unhelp debug levels should be
     # pinned to a higher default.
@@ -47,10 +57,23 @@ def _get_config_file(env=None):
     return os.path.join(dirname, CONFIG_FILE)
 
 
+def _parse_args(argv, default_config_files):
+    logging.register_options(conf.CONF)
+
+    if profiler:
+        profiler.set_defaults(conf.CONF)
+
+    config.set_middleware_defaults()
+
+    conf.CONF(argv[1:], project='nova', version=version_info.version_string(),
+              default_config_files=default_config_files)
+
+
 def init_application():
     # initialize the config system
     conffile = _get_config_file()
-    config.parse_args([], default_config_files=[conffile])
+    _parse_args([], default_config_files=[conffile])
+    db_api.configure(conf.CONF)
 
     # initialize the logging system
     setup_logging(conf.CONF)

nova/db/sqlalchemy/api.py

@@ -79,7 +79,6 @@ LOG = logging.getLogger(__name__)
 
 main_context_manager = enginefacade.transaction_context()
 api_context_manager = enginefacade.transaction_context()
-placement_context_manager = enginefacade.transaction_context()
 
 
 def _get_db_conf(conf_group, connection=None):
@@ -100,12 +99,6 @@ def _context_manager_from_context(context):
 def configure(conf):
     main_context_manager.configure(**_get_db_conf(conf.database))
     api_context_manager.configure(**_get_db_conf(conf.api_database))
-    if conf.placement_database.connection is None:
-        placement_context_manager.configure(
-            **_get_db_conf(conf.api_database))
-    else:
-        placement_context_manager.configure(
-            **_get_db_conf(conf.placement_database))
 
     if profiler_sqlalchemy and CONF.profiler.enabled \
             and CONF.profiler.trace_sqlalchemy:
@@ -148,10 +141,6 @@ def get_api_engine():
     return api_context_manager.get_legacy_facade().get_engine()
 
 
-def get_placement_engine():
-    return placement_context_manager.get_legacy_facade().get_engine()
-
-
 _SHADOW_TABLE_PREFIX = 'shadow_'
 _DEFAULT_QUOTA_NAME = 'default'
 PER_PROJECT_QUOTAS = ['fixed_ips', 'floating_ips', 'networks']

nova/db/sqlalchemy/migration.py

@@ -24,6 +24,7 @@ from oslo_log import log as logging
 import sqlalchemy
 from sqlalchemy.sql import null
 
+from nova.api.openstack.placement import db_api as placement_db
 from nova.db.sqlalchemy import api as db_session
 from nova import exception
 from nova.i18n import _
@@ -43,7 +44,7 @@ def get_engine(database='main', context=None):
     if database == 'api':
         return db_session.get_api_engine()
     if database == 'placement':
-        return db_session.get_placement_engine()
+        return placement_db.get_placement_engine()
 
 
 def db_sync(version=None, database='main', context=None):

nova/tests/fixtures.py

@@ -37,6 +37,7 @@ from requests import adapters
 from wsgi_intercept import interceptor
 
 from nova.api.openstack.compute import tenant_networks
+from nova.api.openstack.placement import db_api as placement_db
 from nova.api.openstack import wsgi_app
 from nova.api import wsgi
 from nova.compute import rpcapi as compute_rpcapi
@@ -580,6 +581,7 @@ class Database(fixtures.Fixture):
         global SESSION_CONFIGURED
         if not SESSION_CONFIGURED:
             session.configure(CONF)
+            placement_db.configure(CONF)
             SESSION_CONFIGURED = True
         self.database = database
         if database == 'main':
@@ -593,7 +595,7 @@ class Database(fixtures.Fixture):
         elif database == 'api':
             self.get_engine = session.get_api_engine
         elif database == 'placement':
-            self.get_engine = session.get_placement_engine
+            self.get_engine = placement_db.get_placement_engine
 
     def _cache_schema(self):
         global DB_SCHEMA
@@ -637,7 +639,7 @@ class DatabaseAtVersion(fixtures.Fixture):
         elif database == 'api':
             self.get_engine = session.get_api_engine
         elif database == 'placement':
-            self.get_engine = session.get_placement_engine
+            self.get_engine = placement_db.get_placement_engine
 
     def cleanup(self):
         engine = self.get_engine()

nova/tests/functional/api/openstack/placement/db/test_consumer.py

@@ -13,13 +13,13 @@
 from oslo_config import cfg
 import sqlalchemy as sa
 
+from nova.api.openstack.placement import db_api
 from nova.api.openstack.placement import exception
 from nova.api.openstack.placement.objects import consumer as consumer_obj
 from nova.api.openstack.placement.objects import project as project_obj
 from nova.api.openstack.placement.objects import resource_provider as rp_obj
 from nova.api.openstack.placement.objects import user as user_obj
 from nova import context
-from nova.db.sqlalchemy import api as db_api
 from nova import test
 from nova.tests import fixtures
 from nova.tests.functional.api.openstack.placement.db import test_base as tb