refstack/refstack/db/utils.py
Vladislav Kuzmin 4e390ee67b Add oslo libraries and command-line utility
Add oslo libraries for works with database and config.
Refactor database relation code. Move it in refstack/db.

Now after istallation of refstack available a command-line
utility: `refstack-manage` and `refstack-api`.

`refstack-manage`

This utlity provide commands for manipulation of database
migrations and setup config file through
--config-file /path/to/refstack.conf option.

Config file should contain database connection string.
For example:

[DEFAULT]
sql_connection = mysql://root:passw0rd@127.0.0.1/refstack

Add ability to runtime updrade/downgrade db through command-line utillity.

`refstack-api`

This utility allow to launch api on gunicorn server. Specify config through
--env REFSTACK_OSLO_CONFIG=/path/to/refstack.conf

Change-Id: Ibea97d433d54d307233aa04e9487f1a1230e7487
2015-02-04 16:54:59 +04:00

55 lines
1.7 KiB
Python

# Copyright (c) 2015 Mirantis, Inc.
# All Rights Reserved.
#
# 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.
"""Utilities for database."""
import logging
from oslo.config import cfg
CONF = cfg.CONF
LOG = logging.getLogger(__name__)
class PluggableBackend(object):
"""A pluggable backend loaded lazily based on some value."""
def __init__(self, pivot, **backends):
self.__backends = backends
self.__pivot = pivot
self.__backend = None
def __get_backend(self):
if not self.__backend:
backend_name = CONF[self.__pivot]
if backend_name not in self.__backends:
raise Exception('Invalid backend: %s' % backend_name)
backend = self.__backends[backend_name]
if isinstance(backend, tuple):
name = backend[0]
fromlist = backend[1]
else:
name = backend
fromlist = backend
self.__backend = __import__(name, None, None, fromlist)
LOG.debug('backend %s', self.__backend)
return self.__backend
def __getattr__(self, key):
backend = self.__get_backend()
return getattr(backend, key)