前面的博客已经将Gunicorn的核心流程给讲完了，剩下的最后其实就是Gunicorn的启动入口了
下面是Gunicorn入口函数：
def run():
"""\
The ``gunicorn`` command line runner for launching Gunicorn with
generic WSGI applications.
"""
from gunicorn.app.wsgiapp import WSGIApplication
WSGIApplication("%(prog)s [OPTIONS] [APP_MODULE]").run()
从代码来看主要涉及以下两个文件：
gunicorn/
├── app
│ ├── base.py
│ └── wsgiapp.py
其中主要涉及以下3个类：
class BaseApplication(object)
class Application(BaseApplication)
class WSGIApplication(Application)
BaseApplication
class BaseApplication(object):
"""
An application interface for configuring and loading
the various necessities for any given web framework.
"""
def __init__(self, usage=None, prog=None):
self.usage = usage
self.cfg = None
self.callable = None
self.prog = prog
self.logger = None
self.do_load_config()
def do_load_config(self):
"""
Loads the configuration
"""
try:
self.load_default_config()
self.load_config()
except Exception as e:
print("\nError: %s" % str(e), file=sys.stderr)
sys.stderr.flush()
sys.exit(1)
def load_default_config(self):
# init configuration
self.cfg = Config(self.usage, prog=self.prog)
def init(self, parser, opts, args):
raise NotImplementedError
def load(self):
raise NotImplementedError
def load_config(self):
"""
This method is used to load the configuration from one or several input(s).
Custom Command line, configuration file.
You have to override this method in your class.
"""
raise NotImplementedError
def reload(self):
self.do_load_config()
if self.cfg.spew:
debug.spew()
def wsgi(self):
if self.callable is None:
self.callable = self.load()
return self.callable
def run(self):
try:
Arbiter(self).run()
except RuntimeError as e:
print("\nError: %s\n" % e, file=sys.stderr)
sys.stderr.flush()
sys.exit(1)
BaseApplication干的事情比较简单，主要4件事：
- 导入配置，主要逻辑在
load_default_config()方法中，其中用户自定义配置导入未实现; - 导入
wsgi app，未实现具体逻辑，由子类去实现； - 启动
Arbiter进程； - 设置解析命令行参数，未实现具体逻辑。
Application
class Application(BaseApplication):
# 'init' and 'load' methods are implemented by WSGIApplication.
# pylint: disable=abstract-method
def chdir(self):
# chdir to the configured path before loading,
# default is the current dir
os.chdir(self.cfg.chdir)
# add the path to sys.path
if self.cfg.chdir not in sys.path:
sys.path.insert(0, self.cfg.chdir)
def get_config_from_filename(self, filename):
if not os.path.exists(filename):
raise RuntimeError("%r doesn't exist" % filename)
cfg = {
"__builtins__": __builtins__,
"__name__": "__config__",
"__file__": filename,
"__doc__": None,
"__package__": None
}
try:
execfile_(filename, cfg, cfg)
except Exception:
print("Failed to read config file: %s" % filename, file=sys.stderr)
traceback.print_exc()
sys.stderr.flush()
sys.exit(1)
return cfg
def get_config_from_module_name(self, module_name):
return vars(util.import_module(module_name))
def load_config_from_module_name_or_filename(self, location):
"""
Loads the configuration file: the file is a python file, otherwise raise an RuntimeError
Exception or stop the process if the configuration file contains a syntax error.
"""
if location.startswith("python:"):
module_name = location[len("python:"):]
cfg = self.get_config_from_module_name(module_name)
else:
if location.startswith("file:"):
filename = location[len("file:"):]
else:
filename = location
cfg = self.get_config_from_filename(filename)
for k, v in cfg.items():
# Ignore unknown names
if k not in self.cfg.settings:
continue
try:
self.cfg.set(k.lower(), v)
except:
print("Invalid value for %s: %s\n" % (k, v), file=sys.stderr)
sys.stderr.flush()
raise
return cfg
def load_config_from_file(self, filename):
return self.load_config_from_module_name_or_filename(location=filename)
def load_config(self):
# parse console args
parser = self.cfg.parser()
args = parser.parse_args()
# optional settings from apps
cfg = self.init(parser, args, args.args)
# set up import paths and follow symlinks
self.chdir()
# Load up the any app specific configuration
if cfg:
for k, v in cfg.items():
self.cfg.set(k.lower(), v)
env_args = parser.parse_args(self.cfg.get_cmd_args_from_env())
if args.config:
self.load_config_from_file(args.config)
elif env_args.config:
self.load_config_from_file(env_args.config)
else:
default_config = get_default_config_file()
if default_config is not None:
self.load_config_from_file(default_config)
# Load up environment configuration
for k, v in vars(env_args).items():
if v is None:
continue
if k == "args":
continue
self.cfg.set(k.lower(), v)
# Lastly, update the configuration with any command line settings.
for k, v in vars(args).items():
if v is None:
continue
if k == "args":
continue
self.cfg.set(k.lower(), v)
# current directory might be changed by the config now
# set up import paths and follow symlinks
self.chdir()
def run(self):
if self.cfg.check_config:
try:
self.load()
except:
msg = "\nError while loading the application:\n"
print(msg, file=sys.stderr)
traceback.print_exc()
sys.stderr.flush()
sys.exit(1)
sys.exit(0)
if self.cfg.spew:
debug.spew()
if self.cfg.daemon:
util.daemonize(self.cfg.enable_stdio_inheritance)
# set python paths
if self.cfg.pythonpath:
paths = self.cfg.pythonpath.split(",")
for path in paths:
pythonpath = os.path.abspath(path)
if pythonpath not in sys.path:
sys.path.insert(0, pythonpath)
super(Application, self).run()
Application主要实现了从文件中导入配置文件的功能。
WSGIApplication
class WSGIApplication(Application):
def init(self, parser, opts, args):
if opts.paste: # paste 配置
app_name = 'main'
path = opts.paste
if '#' in path:
path, app_name = path.split('#')
path = os.path.abspath(os.path.normpath(
os.path.join(util.getcwd(), path)))
if not os.path.exists(path):
raise ConfigError("%r not found" % path)
# paste application, load the config
self.cfgurl = 'config:%s#%s' % (path, app_name)
self.relpath = os.path.dirname(path)
from .pasterapp import paste_config
return paste_config(self.cfg, self.cfgurl, self.relpath)
if not args:
parser.error("No application module specified.")
self.cfg.set("default_proc_name", args[0])
self.app_uri = args[0]
def load_wsgiapp(self):
# load the app
return util.import_app(self.app_uri)
def load_pasteapp(self):
# load the paste app
from .pasterapp import load_pasteapp
return load_pasteapp(self.cfgurl, self.relpath, global_conf=self.cfg.paste_global_conf)
def load(self):
if self.cfg.paste is not None:
return self.load_pasteapp()
else:
return self.load_wsgiapp()
WSGIApplication主要实现的是如何导入实现WSGI协议的app。
一开始看Gunicorn源码，从WSGIApplication开始我也是有点晕，但后面从底层的几个基础类开始看，发现WSGIApplication这个实现就很简单了，一句话，就是“设置运行环境参数，拉起主进程，生成工作进程，开始处理请求”。
