Python日志记录模块发出错误的时区信息 [英] Python logging module emits wrong timezone information

问题描述

我遇到了Python 2.7日志记录模块的问题.我的系统是Ubuntu 14.04 64bit，我住在意大利(目前是UTC + 1，没有夏令时)；系统已正确配置为这样.

I'm running into an issue with Python 2.7 logging module. My system is Ubuntu 14.04 64bit, and I live in Italy (currently UTC+1, no daylight saving); the system is properly configured as such.

我想在当前时区发出日志行，并填写正确的时区偏移信息.

请考虑以下代码段:

#!/usr/bin/env python
import sys
print sys.version_info
import commands
print "System time: %s" % commands.getoutput("date --rfc-3339=seconds")

import logging
import datetime
logging.basicConfig(level=logging.DEBUG, stream=sys.stdout, 
                        format="%(asctime)s:" + logging.BASIC_FORMAT,
                         datefmt="%Y-%m-%dT%H:%M:%S%z")

logger = logging.getLogger()
logger.info("Something happened")

产生以下结果:

sys.version_info(major=2, minor=7, micro=6, releaselevel='final', serial=0)
System time: 2015-01-09 11:21:44+01:00
2015-01-09T11:21:44+0000:INFO:root:Something happened

因此，系统知道正确的时间和偏移量，而Python似乎弄错了时间.

So, the system knows the proper time AND offset, while Python seems to get the time wrong.

在datetime文档中，据说对于strftime中的％z，结果为"UTC偏移量，格式为+ HHMM或-HHMM(如果对象是天真对象，则为空字符串)".

In datetime docs, it is said that for %z in strftime the result is"UTC offset in the form +HHMM or -HHMM (empty string if the the object is naive)".

因此，我期望获得以下任一结果:

So, I would have expected either of the following results:

1. 日志记录模块要登录UTC，所以我会得到类似10:21.44和+0000偏移量的信息；
2. 日志记录模块要登录本地时间，所以我会得到类似11:21:44和+01000偏移量的信息；
3. 日志记录模块提供了朴素的datetime对象，我们完全没有获得偏移量.

相反，在这里我似乎得到了不可预测的-显然是错误的-结果.这是怎么回事?是否可以配置日志记录模块以执行我想要的操作而不会覆盖logging.Formatter对象的转换器功能(当然，我可以在其中做任何我想做的事，但这对我来说显然是个错误)?

On the contrary, here I seem to get an unpredictable - and plainly wrong - result. What's up? Is it possible to configure the logging module to do what I want WITHOUT overriding the converter function of logging.Formatter objects (where, of course, I can do whatever I like, but this looks plainly a bug to me)?

推荐答案

logging使用不在时间元组中存储时区的time模块，与datetime.strftime()不同，time.strftime()不支持%z在Python 2上.您可以覆盖Formatter.formatTime()方法，以使用时区感知日期时间对象作为建议使用@dmg 代替:

logging uses time module that doesn't store timezone in a time tuple and time.strftime() unlike datetime.strftime() doesn't support %z on Python 2. You could override Formatter.formatTime() method to use timezone-aware datetime objects as @dmg suggested instead:

#!/usr/bin/env python
import logging
from datetime import datetime

import tzlocal # $ pip install tzlocal

def posix2local(timestamp, tz=tzlocal.get_localzone()):
    """Seconds since the epoch -> local time as an aware datetime object."""
    return datetime.fromtimestamp(timestamp, tz)

class Formatter(logging.Formatter):
    def converter(self, timestamp):
        return posix2local(timestamp)

    def formatTime(self, record, datefmt=None):
        dt = self.converter(record.created)
        if datefmt:
            s = dt.strftime(datefmt)
        else:
            t = dt.strftime(self.default_time_format)
            s = self.default_msec_format % (t, record.msecs)
        return s

logger = logging.getLogger(__name__)
handler = logging.StreamHandler()
handler.setFormatter(Formatter("%(asctime)s %(message)s", "%Y-%m-%dT%H:%M:%S%z"))
logger.addHandler(handler)
logger.setLevel(logging.DEBUG)

logger.info('something happened')

输出

2015-01-09T18:30:54+0100 something happened

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