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structlog 16.1.0

Structured Logging for Python

structlog makes logging in Python less painful and more powerful by adding structure to your log entries.

It’s up to you whether you want structlog to take care about the output of your log entries or whether you prefer to forward them to an existing logging system like the standard library’s logging module. No monkey patching involved in either case.

Easier Logging

You can stop writing prose and start thinking in terms of an event that happens in the context of key/value pairs:

>>> from structlog import get_logger
>>> log = get_logger()
>>> log.info("key_value_logging", out_of_the_box=True, effort=0)
out_of_the_box=True effort=0 event='key_value_logging'

Each log entry is a meaningful dictionary instead of an opaque string now!

Data Binding

Since log entries are dictionaries, you can start binding and re-binding key/value pairs to your loggers to ensure they are present in every following logging call:

>>> log = log.bind(user="anonymous", some_key=23)
>>> log = log.bind(user="hynek", another_key=42)
>>> log.info("user.logged_in", happy=True)
some_key=23 user='hynek' another_key=42 happy=True event='user.logged_in'

Powerful Pipelines

Each log entry goes through a processor pipeline that is just a chain of functions that receive a dictionary and return a new dictionary that gets fed into the next function. That allows for simple but powerful data manipulation:

def timestamper(logger, log_method, event_dict):
    """Add a timestamp to each log entry."""
    event_dict["timestamp"] = calendar.timegm(time.gmtime())
    return event_dict

There are plenty of processors for most common tasks coming with structlog:

Formatting

structlog is completely flexible about how the resulting log entry is emitted. Since each log entry is a dictionary, it can be formatted to any format:

  • A colorful key/value format for local development,
  • JSON for easy parsing,
  • or some standard format you have parsers for like nginx or Apache httpd.

Internally, formatters are processors whose return value is passed into wrapped loggers and structlog comes with multiple useful formatters out of-the-box.

Output

structlog is also very flexible with the final output of your log entries:

  • A built-in lightweight printer like in the examples above. Easy to configure and fast.
  • Use the standard library’s or Twisted’s logging modules for compatibility. In this case structlog works like a wrapper that formats a string and passes them off into existing systems that won’t ever know that structlog even exists.
  • Don’t format it to a string at all! structlog passes you a dictionary and you can do with it whatever you want. Reported uses cases are sending them out via network or saving them in a database.

Project Information

structlog is dual-licensed under Apache License, version 2 and MIT, available from PyPI, the source code can be found on GitHub, the documentation at http://www.structlog.org/.

structlog targets Python 2.7, 3.4 and newer, and PyPy.

If you need any help, visit us on #structlog on Freenode!

Release Information

16.1.0 (2016-05-24)

Backward-incompatible changes:

  • Python 3.3 and 2.6 aren’t supported anymore. They may work by chance but any effort to keep them working has ceased.

    The last Python 2.6 release was on October 29, 2013 and isn’t supported by the CPython core team anymore. Major Python packages like Django and Twisted dropped Python 2.6 a while ago already.

    Python 3.3 never had a significant user base and wasn’t part of any distribution’s LTS release.

Changes:

  • Add a drop_missing argument to KeyValueRenderer. If key_order is used and a key is missing a value, it’s not rendered at all instead of being rendered as None. #67
  • Exceptions without a __traceback__ are now also rendered on Python 3.
  • Don’t cache loggers in lazy proxies returned from get_logger(). This lead to in-place mutation of them if used before configuration which in turn lead to the problem that configuration was applied only partially to them later. #72

Full changelog.

Authors

structlog is written and maintained by Hynek Schlawack. It’s inspired by previous work done by Jean-Paul Calderone and David Reid.

The development is kindly supported by Variomedia AG.

A full list of contributors can be found on GitHub’s overview. Some of them disapprove of the addition of thread local context data. :)

 
File Type Py Version Uploaded on Size
structlog-16.1.0-py2.py3-none-any.whl (md5, pgp) Python Wheel py2.py3 2016-05-24 28KB
structlog-16.1.0.tar.gz (md5, pgp) Source 2016-05-24 150KB