openstack L版本neutron server启动分析

本文分析的是OpenStack的L版本neutron server的启动流程

首先看下进程信息

4 S neutron  16698     1  1  80   0 - 97381 ep_pol 22:51 ?        00:00:07 /usr/bin/python2 /usr/bin/neutron-server --config-file /usr/share/neutron/neutron-dist.conf --config-dir /usr/shareneutron/server --config-file /etc/neutron/neutron.conf --config-file /etc/neutron/plugin.ini --config-dir /etc/neutron/conf.d/common --config-dir /etc/neutron/conf.d/neutron-server --log-file /var/log/neutron/server.log
1 S neutron  16740 16698  0  80   0 - 98051 ep_pol 22:51 ?        00:00:00 /usr/bin/python2 /usr/bin/neutron-server --config-file /usr/share/neutron/neutron-dist.conf --config-dir /usr/share/neutron/server --config-file /etc/neutron/neutron.conf --config-file /etc/neutron/plugin.ini --config-dir /etc/neutron/conf.d/common --config-dir /etc/neutron/conf.d/neutron-server --log-file /var/log/neutron/server.log

会发现有两个neutron-server进程，而16740是16698的子进程，具体为什么出现这种情况有待探讨。

从上面信息我们得出，neutron-server的执行入口在/usr/bin/neutron-server看下启动的入口脚本

/usr/bin/neutron-server

import sys

from neutron.cmd.eventlet.server import main_wsgi_eventlet
if __name__ == "__main__":
sys.exit(main_wsgi_eventlet())

~

在看下neutron.cmd.eventlet.server，会发现代码如下

from neutron.server import rpc_eventlet
from neutron.server import wsgi_eventlet
from neutron.server import wsgi_pecan

def main_wsgi_eventlet():
wsgi_eventlet.main()

# Eventlet patching is not required for Pecan, but some plugins still spawn
# eventlet threads
def main_wsgi_pecan():
wsgi_pecan.main()

def main_rpc_eventlet():
rpc_eventlet.main()

接着看下netron.server.wsgi_eventlet

import eventlet
from oslo_log import log
from neutron.i18n import _LI
from neutron import server
from neutron import service
LOG = log.getLogger(__name__)
def _eventlet_wsgi_server():
pool = eventlet.GreenPool()
neutron_api = service.serve_wsgi(service.NeutronApiService)
api_thread = pool.spawn(neutron_api.wait)
try:
neutron_rpc = service.serve_rpc()
except NotImplementedError:
LOG.info(_LI("RPC was already started in parent process by "
"plugin."))
else:
rpc_thread = pool.spawn(neutron_rpc.wait)
plugin_workers = service.start_plugin_workers()
for worker in plugin_workers:
pool.spawn(worker.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()
def main():
server.boot_server(_eventlet_wsgi_server)

server.boot_server在server.__init__.py中实现的，具体代码如下

import sys

from oslo_config import cfg

from neutron.common import config

def boot_server(server_func):
# the configuration will be read into the cfg.CONF global data structure
config.init(sys.argv[1:])
config.setup_logging()
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:
server_func()
except KeyboardInterrupt:
pass
except RuntimeError as e:
sys.exit(_("ERROR: %s") % e)

所以，代码中的server_func函数就是_eventlet_wsgi_server，后面的分析继续从_eventlet_wsgi_server即可。