使用python logging的配置

简介

在python中使用logging模块，对log进行配置时，可以使用配置文件，而不用再python源码中进行配置。
这样方便更改logging的配置。

使用basicConfig进行配置

使用logging.basicConfig来加载配置文件。


import logging  LOG_FILENAME="myapp.log"
logging.basicConfig(filename=LOG_FILENAME,level=logging.DEBUG)  logging.debug("this is a debugmsg!")
logging.info("this is a infomsg!")
logging.warn("this is a warn msg!")
logging.error("this is a error msg!")
logging.critical("this is a critical msg!")

使用config.fileConfig进行配置

使用logging.config.fileConfig来加载配置文件。

import logging
import logging.config# 加载配置文件
logging.config.fileConfig("logging2.conf")#create logger
logger = logging.getLogger("simpleExample")
## getLogger中的参数如果在配置文件中找不到，则缺省使用root配置。## log
logger.debug("debug message")
logger.info("info message")
logger.warn("warn message")
logger.error("error message")
logger.critical("critical message")

可以看看fileConfig的具体定义：


def fileConfig(fname, defaults=None, disable_existing_loggers=True):"""Read the logging configuration from a ConfigParser-format file.This can be called several times from an application, allowing an end userthe ability to select from various pre-canned configurations (if thedeveloper provides a mechanism to present the choices and load the chosenconfiguration)."""import ConfigParsercp = ConfigParser.ConfigParser(defaults)if hasattr(fname, 'readline'):cp.readfp(fname)else:cp.read(fname)formatters = _create_formatters(cp)# critical sectionlogging._acquireLock()try:logging._handlers.clear()del logging._handlerList[:]# Handlers add themselves to logging._handlershandlers = _install_handlers(cp, formatters)_install_loggers(cp, handlers, disable_existing_loggers)finally:logging._releaseLock()

配置文件

这里是示例的配置文件

[loggers]
keys=root,simpleExample[handlers]
keys=consoleHandler,fileHandler[formatters]
keys=simpleFormatter[logger_root]
level=DEBUG
handlers=fileHandler[logger_simpleExample]
level=DEBUG
handlers=consoleHandler,fileHandler
qualname=simpleExample
propagate=0[handler_consoleHandler]
class=StreamHandler
level=WARNING
formatter=simpleFormatter
args=(sys.stdout,)[handler_fileHandler]
class=FileHandler
level=DEBUG
formatter=simpleFormatter
args=('testbyconfig.log','a+')[formatter_simpleFormatter]
format=%(asctime)s - %(name)s - %(levelname)s - %(message)s
datefmt=

配置说明[loggers]

在loggers中使用keys定义几个logger，在code中使用。

[loggers]
keys=root,simpleExample

实践中需要注意的是，一般root强制定义。在code中getLogger(“loggerName”)如果不匹配loggerName时，会使用root。

具体的logger项目配置section，使用的section名以logger_连接上具体的名称。如logger_root, logger_simpleExample。

这里是logging中的实现代码

#---------------------------------------------------------------------------
# Utility functions at module level.
# Basically delegate everything to the root logger.
#---------------------------------------------------------------------------def getLogger(name=None):"""Return a logger with the specified name, creating it if necessary.If no name is specified, return the root logger."""if name:return Logger.manager.getLogger(name)else:return root# ... ...class Manager(object):"""There is [under normal circumstances] just one Manager instance, whichholds the hierarchy of loggers."""def __init__(self, rootnode):"""Initialize the manager with the root node of the logger hierarchy."""self.root = rootnodeself.disable = 0self.emittedNoHandlerWarning = 0self.loggerDict = {}self.loggerClass = Nonedef getLogger(self, name):"""Get a logger with the specified name (channel name), creating itif it doesn't yet exist. This name is a dot-separated hierarchicalname, such as "a", "a.b", "a.b.c" or similar.If a PlaceHolder existed for the specified name [i.e. the loggerdidn't exist but a child of it did], replace it with the createdlogger and fix up the parent/child references which pointed to theplaceholder to now point to the logger."""rv = Noneif not isinstance(name, basestring):raise TypeError('A logger name must be string or Unicode')if isinstance(name, unicode):name = name.encode('utf-8')_acquireLock()try:if name in self.loggerDict:rv = self.loggerDict[name]if isinstance(rv, PlaceHolder):ph = rvrv = (self.loggerClass or _loggerClass)(name)rv.manager = selfself.loggerDict[name] = rvself._fixupChildren(ph, rv)self._fixupParents(rv)else:rv = (self.loggerClass or _loggerClass)(name)rv.manager = selfself.loggerDict[name] = rvself._fixupParents(rv)finally:_releaseLock()return rv#... ...

配置说明[logger_name]

在这里配置要使用的logger-handlers：可以使用consoleHandler，fileHandler……。

配置说明[handler_handlerName]

在这里配置要使用logger的handlers的对应的配置.
如class、format、level及对应的args;args是传入class函数的参数。

如consoleHandler对应了

class=StreamHandler
level=WARNING
formatter=simpleFormatter
args=(sys.stdout,)

而 handler_fileHandler 对应的配置

class=FileHandler
level=DEBUG
formatter=simpleFormatter
args=('testbyconfig.log','a+')

配置说明[formatter_simpleFormatter]

这里配置日志的formatter，如：

format=%(asctime)s - %(name)s - %(levelname)s - %(message)s