Python中的不同日志级别

Question

我想做一件我认为很简单的事情。

其实我想用Python的日志模块，记录命令行上所有的信息，并且根据命令行参数设置的级别来记录，同时把日志保存到文件里，文件的日志级别固定为DEBUG。

我试着创建两个不同级别的日志记录器，但这并没有成功；然后我又尝试给两个不同的处理器设置级别，这两个处理器都添加到了根日志记录器上，但这也不行。那么，有没有什么好的建议让我知道该怎么做呢？（我在其他地方看到第二种方法应该是可行的，所以我是不是做错了什么？）

这是我目前设置日志系统的代码：

class LoggerSetup(object):
    """Setup the different logger objects
    """

    def __init__(self):
        self.root_logger = logging.getLogger()
        self.shell_hdlr = logging.StreamHandler()

    #TODO: add another logging handler which stores to a temporary file
    #which should be cleaned up later
    def setup_shell_logger(self, log_level):
        self.root_logger.setLevel(LOG_LEVELS[log_level])
        # in this way the root logger is not set but the handlers are set
        self.shell_hdlr = logging.StreamHandler()
        self.shell_hdlr.setLevel(LOG_LEVELS[log_level])
        self.shell_hdlr.setFormatter(StarFormatter())
        #FIXME: add the support for regular expression exclusion too
        self.root_logger.addHandler(self.shell_hdlr)

    def setup_log_include(self, log_include):
        """Set up the filter to include log messages
        """
        if log_include:
            incl = FilterInclude(log_include)
            self.shell_hdlr.addFilter(incl)

    def setup_log_exclude(self, log_exclude):
        """Set up the filters to exclude log messages
        """
        if log_exclude:
            excl = FilterExclude(log_exclude)
            self.shell_hdlr.addFilter(excl)

    def setup_file_logging(self):
        """Set up the file logger, which always logs in DEBUG mode
        even if the top level logger is set to another level
        """
        #XXX: not working, one possible way to make it work is to create
        #only one log, and different handler/filters to make to handle all
        #the different outputs
        file_handler = logging.FileHandler(LOG_FILENAME)
        # the file logging is always in debug mode
        file_handler.setLevel(logging.DEBUG)
        formatter = logging.Formatter('%(name)-12s: %(levelname)-8s %(message)s - %(asctime)s')
        file_handler.setFormatter(formatter)
        self.root_logger.addHandler(file_handler)

Answer 1

这是我在所有的Python命令行应用中使用的一个东西。虽然有点啰嗦，但你应该能得到一个记录器，它可以接受一个可选参数，这样就能在任何级别创建一个控制台记录器，而不管文件中记录的内容是什么：

#!/usr/bin/env python
import logging
from argparse import ArgumentParser

COMPANY_LOGGER = 'COMPANY.Python.Logger'
CONSL_LEVEL_RANGE = range(0, 51)
LOG_FILE = 'company.log'
FORMAT_STR = '%(asctime)s %(levelname)s %(message)s'

parser = ArgumentParser()
parser.add_argument('-c', '--console-log', metavar='ARG',
                    type=int, choices=range(0, 51),
                    action='store', dest='console_log',
                    default=None,
                    help='Adds a console logger for the level specified in the range 1..50')

args = parser.parse_args()

# Create logger
logger = logging.getLogger(COMPANY_LOGGER)
logger.setLevel(logging.DEBUG)
formatter = logging.Formatter(FORMAT_STR)

# Add FileHandler and only log WARNING and higher
fh = logging.FileHandler(LOG_FILE)
fh.name = 'File Logger'
fh.level = logging.WARNING
fh.formatter = formatter
logger.addHandler(fh)

# Add optional ConsoleHandler
if args.console_log:
    ch = logging.StreamHandler()
    ch.name = 'Console Logger'
    ch.level = args.console_log
    ch.formatter = formatter
    logger.addHandler(ch)

logger.debug('DEBUG')
logger.info('INFO')
logger.warning('WARNING')
logger.critical('CRITICAL')

当从命令行运行时，我们可以看到记录级别的不同。

-c1代表“DEBUG及以上”（这是最详细的），但company.log文件中仍然只记录WARNING及以上的内容：

~ zacharyyoung$ ./so.py -c1
2012-01-12 08:59:50,086 DEBUG DEBUG
2012-01-12 08:59:50,086 INFO INFO
2012-01-12 08:59:50,087 WARNING WARNING
2012-01-12 08:59:50,087 CRITICAL CRITICAL

~ zacharyyoung$ cat company.log 
2012-01-12 08:59:50,087 WARNING WARNING
2012-01-12 08:59:50,087 CRITICAL CRITICAL

-c20代表INFO：

~ zacharyyoung$ ./so.py -c20
2012-01-12 09:00:09,393 INFO INFO
2012-01-12 09:00:09,393 WARNING WARNING
2012-01-12 09:00:09,393 CRITICAL CRITICAL

~ zacharyyoung$ cat company.log 
2012-01-12 08:59:50,087 WARNING WARNING
2012-01-12 08:59:50,087 CRITICAL CRITICAL
2012-01-12 09:00:09,393 WARNING WARNING
2012-01-12 09:00:09,393 CRITICAL CRITICAL