# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# 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.

"""Starter script for Nova Compute."""

import sys
import traceback

from oslo.config import cfg

from nova import config
import nova.db.api
from nova import exception
from nova.openstack.common import log as logging
from nova import service
from nova import utils

CONF = cfg.CONF
CONF.import_opt('compute_topic', 'nova.compute.rpcapi')
CONF.import_opt('use_local', 'nova.conductor.api', group='conductor')


def block_db_access():
    class NoDB(object):
        def __getattr__(self, attr):
            return self

        def __call__(self, *args, **kwargs):
            stacktrace = "".join(traceback.format_stack())
            LOG = logging.getLogger('nova.compute')
            LOG.error('No db access allowed in nova-compute: %s' % stacktrace)
            raise exception.DBNotAllowed('nova-compute')

    nova.db.api.IMPL = NoDB()


def main():
    config.parse_args(sys.argv)
    logging.setup('nova')
    utils.monkey_patch()

    if not CONF.conductor.use_local:
        block_db_access()

    server = service.Service.create(binary='nova-compute',
                                    topic=CONF.compute_topic,
                                    db_allowed=False)
    service.serve(server)
    service.wait()