nova-api源码-启动服务
结构地图
nova-api服务是nova组件的入口，在启动时存在大量初始化的操作，比如加载api、创建wsgi server、策略加载等。对于openstack中所有组件而言，项目中的setup.cfg文件，就是组件的结构地图，其中包含了所有服务的入口。
console_scripts =
nova-api = nova.cmd.api:main
nova-api-metadata = nova.cmd.api_metadata:main
nova-api-os-compute = nova.cmd.api_os_compute:main
nova-compute = nova.cmd.compute:main
nova-conductor = nova.cmd.conductor:main
nova-manage = nova.cmd.manage:main
nova-novncproxy = nova.cmd.novncproxy:main
nova-policy = nova.cmd.policy:main
nova-rootwrap = oslo_rootwrap.cmd:main
nova-rootwrap-daemon = oslo_rootwrap.cmd:daemon
nova-scheduler = nova.cmd.scheduler:main
nova-serialproxy = nova.cmd.serialproxy:main
nova-spicehtml5proxy = nova.cmd.spicehtml5proxy:main
nova-status = nova.cmd.status:main
线上环境也可以通过查看entry_points文件：
# /usr/lib/python2.7/site-packages/nova-20.6.0-py2.7.egg-info/entry_points.txt
[console_scripts]
nova-api = nova.cmd.api:main
nova-api-metadata = nova.cmd.api_metadata:main
nova-api-os-compute = nova.cmd.api_os_compute:main
nova-compute = nova.cmd.compute:main
nova-conductor = nova.cmd.conductor:main
nova-console = nova.cmd.console:main
nova-dhcpbridge = nova.cmd.dhcpbridge:main
nova-manage = nova.cmd.manage:main
nova-network = nova.cmd.network:main
nova-novncproxy = nova.cmd.novncproxy:main
nova-policy = nova.cmd.policy:main
nova-rootwrap = oslo_rootwrap.cmd:main
nova-rootwrap-daemon = oslo_rootwrap.cmd:daemon
nova-scheduler = nova.cmd.scheduler:main
nova-serialproxy = nova.cmd.serialproxy:main
nova-spicehtml5proxy = nova.cmd.spicehtml5proxy:main
nova-status = nova.cmd.status:main
nova-xvpvncproxy = nova.cmd.xvpvncproxy:main
服务入口
nova-api的入口文件：
# nova/cmd/api.py
def main():
config.parse_args(sys.argv)
logging.setup(CONF, "nova")
objects.register_all()
gmr_opts.set_defaults(CONF)
if 'osapi_compute' in CONF.enabled_apis:
# NOTE(mriedem): This is needed for caching the nova-compute service
# version.
objects.Service.enable_min_version_cache()
log = logging.getLogger(__name__)
gmr.TextGuruMeditation.setup_autorun(version, conf=CONF)
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("%s. ``enabled_apis`` includes bad values. "
"Fix to remove this warning.", ex)
if started == 0:
log.error('No APIs were started. '
'Check the enabled_apis config option.')
sys.exit(1)
launcher.wait()
服务启动时，config.parse_args(sys.argv)就先获取配置参数。nova服务的配置在/etc/nova/nova.conf文件中。
[DEFAULT]
#
# From nova.conf
#
#
# Availability zone for internal services. For more information, refer to the
# documentation. (string value)
#internal_service_availability_zone=internal
#
# Default availability zone for compute services. For more information, refer to
# the documentation. (string value)
#default_availability_zone=nova
... ...
nova-api入口函数中最重要的两句代码为：
server = service.WSGIService(api, use_ssl=should_use_ssl)
launcher.launch_service(server, workers=server.workers or 1)
根据nova参数配置中的enabled_apis选项，先声明一个WSGIService实例，第一个参数就是enabled_apis中配置的一项，再通过launch_service启动这个WSGI服务。
配置加载
# nova/config.py
def parse_args(argv, default_config_files=None, configure_db=True,
init_rpc=True):
log.register_options(CONF)
# NOTE(sean-k-mooney): this filter addresses bug #1825584
# https://bugs.launchpad.net/nova/+bug/1825584
# eventlet monkey-patching breaks AMQP heartbeat on uWSGI
rabbit_logger = logging.getLogger('oslo.messaging._drivers.impl_rabbit')
rabbit_logger.addFilter(rabbit_heartbeat_filter)
# 配置默认值 包括wsgi服务中间件 消息队列交换器
set_lib_defaults()
if profiler:
profiler.set_defaults(CONF)
CONF(argv[1:],
project='nova',
version=version.version_string(),
default_config_files=default_config_files)
# 声明一个rpc server
if init_rpc:
rpc.init(CONF)
if configure_db:
main_db_api.configure(CONF)
api_db_api.configure(CONF)
配置默认值：
def set_lib_defaults():
"""Update default value for configuration options from other namespace.
Example, oslo lib config options. This is needed for
config generator tool to pick these default value changes.
https://docs.openstack.org/oslo.config/latest/cli/
generator.html#modifying-defaults-from-other-namespaces
"""
# Update default value of oslo.middleware cors config option.
middleware.set_defaults()
# Update default value of RPC transport control_exchange config option.
rpc.set_defaults(control_exchange='nova')
# Update default value of oslo_log default_log_levels and
# logging_context_format_string config option.
set_log_defaults()
# Update default value of oslo.policy policy_file config option.
policy_opts.set_defaults(CONF, policy.DEFAULT_POLICY_FILE)
WSGI启动
# 声明一个process_launcher实例
launcher = service.process_launcher()
# 声明WSGI
server = service.WSGIService(api, use_ssl=should_use_ssl)
# 加入launcher中启动
launcher.launch_service(server, workers=server.workers or 1)
launcher声明实际调用oslo-service库实现
# nova/service.py
def process_launcher():
return service.ProcessLauncher(CONF, restart_method='mutate')
oslo-service：
# oslo_service/service.py
class ProcessLauncher(object):
"""Launch a service with a given number of workers."""
def __init__(self, conf, wait_interval=0.01, restart_method='reload'):
"""Constructor.
:param conf: an instance of ConfigOpts
:param wait_interval: The interval to sleep for between checks
of child process exit.
:param restart_method: If 'reload', calls reload_config_files on
SIGHUP. If 'mutate', calls mutate_config_files on SIGHUP. Other
values produce a ValueError.
"""
self.conf = conf
conf.register_opts(_options.service_opts)
self.children = {}
self.sigcaught = None
self.running = True
self.wait_interval = wait_interval
self.launcher = None
rfd, self.writepipe = os.pipe()
self.readpipe = eventlet.greenio.GreenPipe(rfd, 'r')
self.signal_handler = SignalHandler()
self.handle_signal()
self.restart_method = restart_method
if restart_method not in _LAUNCHER_RESTART_METHODS:
raise ValueError(_("Invalid restart_method: %s") % restart_method)
WSGI实例：
# nova/service.py
class WSGIService(service.Service):
"""Provides ability to launch API from a 'paste' configuration."""
def __init__(self, name, loader=None, use_ssl=False, max_url_len=None):
"""Initialize, but do not start the WSGI server.
: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
# NOTE(danms): Name can be metadata, osapi_compute, per
# nova.service's enabled_apis
self.binary = 'nova-%s' % name
LOG.warning('Running %s using eventlet is deprecated. Deploy with '
'a WSGI server such as uwsgi or mod_wsgi.', self.binary)
self.topic = None
self.manager = self._get_manager()
self.loader = loader or api_wsgi.Loader()
self.app = self.loader.load_app(name)
# inherit all compute_api worker counts from osapi_compute
if name.startswith('openstack_compute_api'):
wname = 'osapi_compute'
else:
wname = name
self.host = getattr(CONF, '%s_listen' % name, "0.0.0.0")
self.port = getattr(CONF, '%s_listen_port' % name, 0)
self.workers = (getattr(CONF, '%s_workers' % wname, 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)s is invalid, "
"must be greater than 0") %
{'worker_name': worker_name,
'workers': str(self.workers)})
raise exception.InvalidInput(msg)
self.use_ssl = use_ssl
self.server = wsgi.Server(name,
self.app,
host=self.host,
port=self.port,
use_ssl=self.use_ssl,
max_url_len=max_url_len)
# Pull back actual port used
self.port = self.server.port
self.backdoor_port = None
setup_profiler(name, self.host)
启动WSGI
def launch_service(self, service, workers=1):
"""Launch a service with a given number of workers.
:param service: a service to launch, must be an instance of
:class:`oslo_service.service.ServiceBase`
:param workers: a number of processes in which a service
will be running
"""
_check_service_base(service)
wrap = ServiceWrapper(service, workers)
# Hide existing objects from the garbage collector, so that most
# existing pages will remain in shared memory rather than being
# duplicated between subprocesses in the GC mark-and-sweep. (Requires
# Python 3.7 or later.)
if hasattr(gc, 'freeze'):
gc.freeze()
LOG.info('Starting %d workers', wrap.workers)
while self.running and len(wrap.children) < wrap.workers:
self._start_child(wrap)
def _start_child(self, wrap):
if len(wrap.forktimes) > wrap.workers:
# Limit ourselves to one process a second (over the period of
# number of workers * 1 second). This will allow workers to
# start up quickly but ensure we don't fork off children that
# die instantly too quickly.
if time.time() - wrap.forktimes[0] < wrap.workers:
LOG.info('Forking too fast, sleeping')
time.sleep(1)
wrap.forktimes.pop(0)
wrap.forktimes.append(time.time())
pid = os.fork()
if pid == 0:
self.launcher = self._child_process(wrap.service)
while True:
self._child_process_handle_signal()
status, signo = self._child_wait_for_exit_or_signal(
self.launcher)
if not _is_sighup_and_daemon(signo):
self.launcher.wait()
break
self.launcher.restart()
os._exit(status)
LOG.debug('Started child %d', pid)
wrap.children.add(pid)
self.children[pid] = wrap
return pid
作者：红雨
出处：https://www.cnblogs.com/52why
微信公众号： 红雨python
