Neutron分析（2）——neutron-server启动过程分析

import sys
from neutron.server import main

if __name__ == "__main__":
    sys.exit(main())

ef main():
    # the configuration will be read into the cfg.CONF global data structure
    config.init(sys.argv[1:])
    if not cfg.CONF.config_file:
        sys.exit(_("ERROR: Unable to find configuration file via the default"
                   " search paths (~/.neutron/, ~/, /etc/neutron/, /etc/) and"
                   " the ‘--config-file‘ option!"))
    try:
        pool = eventlet.GreenPool()

        # 以协程方式启动Restful API
        neutron_api = service.serve_wsgi(service.NeutronApiService)
        api_thread = pool.spawn(neutron_api.wait)

        # 启动RPC API
        try:
            neutron_rpc = service.serve_rpc()
        except NotImplementedError:
            LOG.info(_("RPC was already started in parent process by plugin."))
        else:
            rpc_thread = pool.spawn(neutron_rpc.wait)

            # api and rpc should die together.  When one dies, kill the other.
            rpc_thread.link(lambda gt: api_thread.kill())
            api_thread.link(lambda gt: rpc_thread.kill())

        pool.waitall()
    except KeyboardInterrupt:
        pass
    except RuntimeError as e:
        sys.exit(_("ERROR: %s") % e)

plugin = manager.NeutronManager.get_plugin()

try:
        rpc = RpcWorker(plugin)

        if cfg.CONF.rpc_workers < 1:
            rpc.start()
            return rpc
        else:
            launcher = common_service.ProcessLauncher(wait_interval=1.0)
            launcher.launch_service(rpc, workers=cfg.CONF.rpc_workers)
            return launcher

def start(self):
        # We may have just forked from parent process.  A quick disposal of the
        # existing sql connections avoids producing errors later when they are
        # discovered to be broken.
        session.get_engine().pool.dispose()
        self._servers = self._plugin.start_rpc_listeners()

def serve_wsgi(cls):

    try:
        service = cls.create()
        service.start()
    except Exception:
        with excutils.save_and_reraise_exception():
            LOG.exception(_(‘Unrecoverable error: please check log ‘
                            ‘for details.‘))

    return service

def _run_wsgi(app_name):
    app = config.load_paste_app(app_name)
    if not app:
        LOG.error(_(‘No known API applications configured.‘))
        return
    server = wsgi.Server("Neutron")
    server.start(app, cfg.CONF.bind_port, cfg.CONF.bind_host,
                 workers=cfg.CONF.api_workers)
    # Dump all option values here after all options are parsed
    cfg.CONF.log_opt_values(LOG, std_logging.DEBUG)
    LOG.info(_("Neutron service started, listening on %(host)s:%(port)s"),
             {‘host‘: cfg.CONF.bind_host,
              ‘port‘: cfg.CONF.bind_port})
    return server