https://github.com/wimglenn/logging_tz

Specify the UTC offset (%z) in Python 2 logging
https://github.com/wimglenn/logging_tz

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Specify the UTC offset (%z) in Python 2 logging

• Host: GitHub
• URL: https://github.com/wimglenn/logging_tz
• Owner: wimglenn
• Created: 2017-12-01T01:27:19.000Z (about 7 years ago)
• Default Branch: master
• Last Pushed: 2018-09-20T02:53:18.000Z (over 6 years ago)
• Last Synced: 2024-12-18T12:19:05.511Z (22 days ago)
• Language: Python
• Size: 8.79 KB
• Stars: 0
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.rst

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README

        
Using local time in Python2 logging

===================================

Python 2 logging module doesn't support using a timezone offset ``%z`` in the datetime format string.  An example failure mode is shown below:

.. code-block:: python

   import logging

   datefmt = '%Y-%m-%d %H:%M:%S%z'

   logging.basicConfig(format='%(asctime)s %(message)s', datefmt=datefmt)

   logging.warning("Dude, where's my tzinfo?")  # it's about 6.20 pm here in Chicago

   # 2017-02-27 18:23:05+0000 Dude, where's my tzinfo?

                        ^^^^^

Simply omitting the time zone offset would perhaps have been admissible, or perhaps even simply refusing to localize and just logging in UTC, but specifying the localized time **and** specifying a zero offset is certainly wrong.  The part marked ``^`` is incorrect, an offset timestamp should have looked more like this one:

.. code-block:: python

   import pytz

   from datetime import datetime

   chicago_now = datetime.now(tz=pytz.timezone('America/Chicago'))

   print chicago_now.strftime(datefmt)

   # 2017-02-27 18:23:13-0600

Indeed, that's how the logging output *does* look if run under Python 3.  But in Python 2, the ``%z`` directive is dropped.  This module provides a ``LocalFormatter`` intended as a drop-in replacement, to provide the correct handling of time zone offsets under Python 2:

.. code-block:: python

   import logging, logging_tz

   datefmt = '%Y-%m-%d %H:%M:%S%z'

   logger = logging.getLogger('wat')

   handler = logging.StreamHandler()

   formatter = logging_tz.LocalFormatter(fmt='%(asctime)s %(message)s', datefmt=datefmt)

   handler.setFormatter(formatter)

   logger.addHandler(handler)

   logger.warning("Ah, there's my tzinfo!")

   # 2017-02-27 18:25:53-0600 Ah, there's my tzinfo!

Additionally a ``ChicagoFormatter`` is offered as a convenience, to ease the pain for anyone insane enough to run their backend on CST instead of UTC.

FAQ

---

Q:

  How to install this library?

A:

  ``pip install logging_tz`` and then you can just use a ``logging_tz.LocalFormatter`` instead of the ``logging.Formatter``.

Q:

  You should log in UTC.  Why would you log in local time anyway?

A:

  `Yeah, I guess `_.  Although handling the date format correctly is at least better than mucking it up completely.

Q:

  Is that a bug in Python?

A:

  Hmm, arguably not, because the ``%z`` directive for time zone offset is not listed on the ``time.strftime`` table in the `Python 2 documentation `_.  It is `there in the Python 3 docs `_, though.

Q:

  Did people really ask you these questions?  I bet you just made them up for the FAQ.

A:

  That's a very good question - it's one I've frequently asked myself, in fact.