nova-api nova-compute 启动服务的时候有的没有加配置文件有的加了

nova/nova/cmd/api.py
from nova import config

def main():
    config.parse_args(sys.argv)
    logging.setup(CONF, "nova")
    utils.monkey_patch()
    objects.register_all()
    if 'osapi_compute' in CONF.enabled_apis:
        # NOTE(mriedem): This is needed for caching the nova-compute service
        # version which is looked up when a server create request is made with
        # network id of 'auto' or 'none'.
        objects.Service.enable_min_version_cache()
    log = logging.getLogger(__name__)

    gmr.TextGuruMeditation.setup_autorun(version)

    launcher = service.process_launcher()
    started = 0
    for api in CONF.enabled_apis:
        should_use_ssl = api in CONF.enabled_ssl_apis
        try:
            server = service.WSGIService(api, use_ssl=should_use_ssl)
            launcher.launch_service(server, workers=server.workers or 1)
            started += 1
        except exception.PasteAppNotFound as ex:
            log.warning(
                _LW("%s. ``enabled_apis`` includes bad values. "
                    "Fix to remove this warning."), six.text_type(ex))

    if started == 0:
        log.error(_LE('No APIs were started. '
                      'Check the enabled_apis config option.'))
        sys.exit(1)

    launcher.wait()

nova/nova/config.py

def parse_args(argv, default_config_files=None, configure_db=True,
               init_rpc=True):
    log.register_options(CONF)
    # We use the oslo.log default log levels which includes suds=INFO
    # and add only the extra levels that Nova needs
    if CONF.glance.debug:
        extra_default_log_levels = ['glanceclient=DEBUG']
    else:
        extra_default_log_levels = ['glanceclient=WARN']
    log.set_defaults(default_log_levels=log.get_default_log_levels() +
                     extra_default_log_levels)
    rpc.set_defaults(control_exchange='nova')
    config.set_middleware_defaults()

    CONF(argv[1:],    代码从这里跟进去会用到第三方库，然后会去查找配置文件从etc 下面
         project='nova',
         version=version.version_string(),
         default_config_files=default_config_files)

    if init_rpc:
        rpc.init(CONF)

    if configure_db:
        sqlalchemy_api.configure(CONF)