1、启动cinder-api服务
当你通过cinder-api命令（如：/usr/bin/cinder-api --config-file /etc/cinder/cinder.conf）启动api服务时，执行的实际上是
cinder/cmd/api.py/main()函数， 如下：
[root@xgto02n010027244133 ~]# cat /usr/bin/cinder-api
#!/usr/bin/python2
# PBR Generated from u'console_scripts'
import sys
from cinder.cmd.api import main
if __name__ == "__main__":
sys.exit(main())
cinder/cmd/api.py/main()函数，内容如下：
def main():
objects.register_all() #加载辅助对象，封装与数据库相关的操作
gmr_opts.set_defaults(CONF) #oslo_reports模块，用于生成错误报告，如内存泄漏等
CONF(sys.argv[1:], project='cinder',
version=version.version_string())
config.set_middleware_defaults()
logging.setup(CONF, "cinder")
python_logging.captureWarnings(True)
utils.monkey_patch() # monkey-patch，替换库比如socket、thread等，不改变import的行为，改变的是操作的指向函数
gmr.TextGuruMeditation.setup_autorun(version, conf=CONF)
"""初始化rpc：
设置全局Transport和Notifier,Transport是
oslo_messaging/transport.py/Transport实例，我采用的是默认的
rpc_backend=rabbit，所以Transport采用的driver=oslo_messaging/
_drivers/impl_rabbit.py/RabbitDriver；Notifier是一个通知消息发
送器，它借助Transport将通知发送发送给ceilometer
"""
rpc.init(CONF)
#通过服务启动器启动WSGI服务（`osapi_volume`）并等待服务启动成功
#在初始化WSGI服务时，会设置路由映射以及加载WSGI应用程序
#在启动WSGI服务时，会启动http监听
launcher = service.process_launcher()
server = service.WSGIService('osapi_volume') #创建一个名为`osapi_volume`的`WSGIService`服务对象 ，2里面详解
launcher.launch_service(server, workers=server.workers)
launcher.wait()
2、创建 WSGIService 服务对象
from oslo_service import wsgi
from cinder import service
cinder/service.py:class WSGIService(service.ServiceBase):
class WSGIService(service.ServiceBase):
"""Provides ability to launch API from a 'paste' configuration."""
def __init__(self, name, loader=None):
"""Initialize, but do not start the WSGI server.
初始化，但是并不启动wsgi server服务
:param name: The name of the WSGI server given to the loader.
:param loader: Loads the WSGI application using the given name.
:returns: None
"""
self.name = name #服务名`osapi_volume`
self.manager = self._get_manager() #加载名为（`osapi_volume_manager`）的管理器，返回值为None）
#创建WSGI应用加载器，并根据配置文件(`cinder.conf`)设置应用配置路径，config_path` = `/etc/cinder/api-paste.ini‘
self.loader = loader or wsgi.Loader(CONF) #该函数会寻找cinder.conf文件中 api_paste_config 参数对应的配置文件，并保存到变量中
self.app = self.loader.load_app(name) #加载WSGI应用并设置路由映射，return paste.urlmap.URLMap
"""
根据配置文件(`cinder.conf`)设置监听地址及工作线程数
如果未指定监听ip及端口就分别设置为`0.0.0.0`及`0`
如果为指定工作线程数就设置为cpu个数
如果设置的工作线程数小于1，则抛异常
"""
self.host = getattr(CONF, '%s_listen' % name, "0.0.0.0")
self.port = getattr(CONF, '%s_listen_port' % name, 0)
self.use_ssl = getattr(CONF, '%s_use_ssl' % name, False)
self.workers = (getattr(CONF, '%s_workers' % name, None) or
processutils.get_worker_count())
if self.workers and self.workers < 1:
worker_name = '%s_workers' % name
msg = (_("%(worker_name)s value of %(workers)d is invalid, "
"must be greater than 0.") %
{'worker_name': worker_name,
'workers': self.workers})
raise exception.InvalidInput(msg)
"""如果CONF.profiler.enabled = True就开启性能分析
创建一个类型为`Messaging`的通知器(`_notifier`)，将性能数据发送给
ceilometer
"""
setup_profiler(name, self.host)
##创建WSGI服务器对象
self.server = wsgi.Server(CONF,
name,
self.app,
host=self.host,
port=self.port,
use_ssl=self.use_ssl)
在cinder.conf配置文件中与cinder api服务有关的参数
# File name for the paste.deploy config for api service (string value)
api_paste_config = /etc/cinder/api-paste.ini
在初始化WSGIService服务对象过程中，主要完成了如下操作：
1)加载WSGI Application（Python Paste Deployment）
2)设置路由映射（Python Routes）
3)创建WSGI服务器对象并完成初始化
2.1 对wsgi的使用
oslo_service/wsgi.py
class Loader(object):
"""Used to load WSGI applications from paste configurations."""
def __init__(self, conf):
"""Initialize the loader, and attempt to find the config.
:param conf: Application config
:returns: None
"""
conf.register_opts(_options.wsgi_opts)
self.config_path = None
config_path = conf.api_paste_config
if not os.path.isabs(config_path):
self.config_path = conf.find_file(config_path)
elif os.path.exists(config_path):
self.config_path = config_path
if not self.config_path:
raise ConfigNotFound(path=config_path)
def load_app(self, name):
"""Return the paste URLMap wrapped WSGI application.
:param name: Name of the application to load.
:returns: Paste URLMap object wrapping the requested application.
:raises: PasteAppNotFound
"""
try:
LOG.debug("Loading app %(name)s from %(path)s",
{'name': name, 'path': self.config_path})
return deploy.loadapp("config:%s" % self.config_path, name=name)
except LookupError:
LOG.exception("Couldn't lookup app: %s", name)
raise PasteAppNotFound(name=name, path=self.config_path)
配置文件api-paste.ini内容如下
[composite:osapi_volume] use = call:cinder.api:root_app_factory /: apiversions /v1: openstack_volume_api_v1 /v2: openstack_volume_api_v2 /v3: openstack_volume_api_v3 [composite:openstack_volume_api_v1] use = call:cinder.api.middleware.auth:pipeline_factory noauth = cors http_proxy_to_wsgi request_id faultwrap sizelimit osprofiler noauth apiv1 keystone = cors http_proxy_to_wsgi request_id faultwrap sizelimit osprofiler authtoken keystonecontext apiv1 keystone_nolimit = cors http_proxy_to_wsgi request_id faultwrap sizelimit osprofiler authtoken keystonecontext apiv1 [composite:openstack_volume_api_v2] use = call:cinder.api.middleware.auth:pipeline_factory noauth = cors http_proxy_to_wsgi request_id faultwrap sizelimit osprofiler noauth apiv2 keystone = cors http_proxy_to_wsgi request_id faultwrap sizelimit osprofiler authtoken keystonecontext apiv2 keystone_nolimit = cors http_proxy_to_wsgi request_id faultwrap sizelimit osprofiler authtoken keystonecontext apiv2 cinder.conf文件中的api启动的配置 这三个参数控制的是api 版本的控制 # DEPRECATED: Deploy v1 of the Cinder API. (boolean value) # This option is deprecated for remoervice_down_timeal. # Its value may be silently ignored in the future. #enable_v1_api = false--------不加载v1对应的app # DEPRECATED: Deploy v2 of the Cinder API. (boolean value) # This option is deprecated for removal. # Its value may be silently ignored in the future. #enable_v2_api = True------------加载v2对应的app # Deploy v3 of the Cinder API. (boolean value) enable_v3_api = True-------------加载v3对应的app # The strategy to use for auth. Supports noauth or keystone. (string value) # Allowed values: noauth, keystone auth_strategy = keystone----------这个参数控制的api-paste.ini中选择哪一种认证方式