DESCRIPTION.rst 7.0 KB

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  1. .. image:: http://www.structlog.org/en/latest/_static/structlog_logo_small.png
  2. :alt: structlog Logo
  3. :width: 256px
  4. :target: http://www.structlog.org/
  5. ========================================
  6. structlog: Structured Logging for Python
  7. ========================================
  8. .. image:: https://readthedocs.org/projects/structlog/badge/?version=stable
  9. :target: https://structlog.readthedocs.io/en/stable/?badge=stable
  10. :alt: Documentation Status
  11. .. image:: https://travis-ci.org/hynek/structlog.svg?branch=master
  12. :target: https://travis-ci.org/hynek/structlog
  13. .. image:: https://codecov.io/github/hynek/structlog/branch/master/graph/badge.svg
  14. :target: https://codecov.io/github/hynek/structlog
  15. :alt: Test Coverage
  16. .. image:: https://www.irccloud.com/invite-svg?channel=%23structlog&hostname=irc.freenode.net&port=6697&ssl=1
  17. :target: https://www.irccloud.com/invite?channel=%23structlog&hostname=irc.freenode.net&port=6697&ssl=1
  18. .. begin
  19. ``structlog`` makes logging in Python less painful and more powerful by adding structure to your log entries.
  20. 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.
  21. *No* `monkey patching <https://en.wikipedia.org/wiki/Monkey_patch>`_ involved in either case.
  22. Easier Logging
  23. ==============
  24. You can stop writing prose and start thinking in terms of an event that happens in the context of key/value pairs:
  25. .. code-block:: pycon
  26. >>> from structlog import get_logger
  27. >>> log = get_logger()
  28. >>> log.info("key_value_logging", out_of_the_box=True, effort=0)
  29. 2016-04-20 16:20.13 key_value_logging effort=0 out_of_the_box=True
  30. Each log entry is a meaningful dictionary instead of an opaque string now!
  31. Data Binding
  32. ============
  33. 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:
  34. .. code-block:: pycon
  35. >>> log = log.bind(user="anonymous", some_key=23)
  36. >>> log = log.bind(user="hynek", another_key=42)
  37. >>> log.info("user.logged_in", happy=True)
  38. 2016-04-20 16:20.13 user.logged_in another_key=42 happy=True some_key=23 user='hynek'
  39. Powerful Pipelines
  40. ==================
  41. Each log entry goes through a `processor pipeline <http://www.structlog.org/en/stable/processors.html>`_ that is just a chain of functions that receive a dictionary and return a new dictionary that gets fed into the next function.
  42. That allows for simple but powerful data manipulation:
  43. .. code-block:: python
  44. def timestamper(logger, log_method, event_dict):
  45. """Add a timestamp to each log entry."""
  46. event_dict["timestamp"] = time.time()
  47. return event_dict
  48. There are `plenty of processors <http://www.structlog.org/en/stable/api.html#module-structlog.processors>`_ for most common tasks coming with ``structlog``:
  49. - Collectors of `call stack information <http://www.structlog.org/en/stable/api.html#structlog.processors.StackInfoRenderer>`_ ("How did this log entry happen?"),
  50. - …and `exceptions <http://www.structlog.org/en/stable/api.html#structlog.processors.format_exc_info>`_ ("What happened‽").
  51. - Unicode encoders/decoders.
  52. - Flexible `timestamping <http://www.structlog.org/en/stable/api.html#structlog.processors.TimeStamper>`_.
  53. Formatting
  54. ==========
  55. ``structlog`` is completely flexible about *how* the resulting log entry is emitted.
  56. Since each log entry is a dictionary, it can be formatted to **any** format:
  57. - A colorful key/value format for `local development <http://www.structlog.org/en/stable/development.html>`_,
  58. - `JSON <http://www.structlog.org/en/stable/api.html#structlog.processors.JSONRenderer>`_ for easy parsing,
  59. - or some standard format you have parsers for like nginx or Apache httpd.
  60. Internally, formatters are processors whose return value (usually a string) is passed into loggers that are responsible for the output of your message.
  61. ``structlog`` comes with multiple useful formatters out of-the-box.
  62. Output
  63. ======
  64. ``structlog`` is also very flexible with the final output of your log entries:
  65. - A **built-in** lightweight printer like in the examples above.
  66. Easy to use and fast.
  67. - Use the **standard library**'s or **Twisted**'s logging modules for compatibility.
  68. 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.
  69. Or the other way round: ``structlog`` comes with a ``logging`` formatter that allows for processing third party log records.
  70. - Don't format it to a string at all!
  71. ``structlog`` passes you a dictionary and you can do with it whatever you want.
  72. Reported uses cases are sending them out via network or saving them in a database.
  73. .. -end-
  74. Project Information
  75. ===================
  76. ``structlog`` is dual-licensed under `Apache License, version 2 <http://choosealicense.com/licenses/apache/>`_ and `MIT <http://choosealicense.com/licenses/mit/>`_, available from `PyPI <https://pypi.python.org/pypi/structlog/>`_, the source code can be found on `GitHub <https://github.com/hynek/structlog>`_, the documentation at http://www.structlog.org/.
  77. ``structlog`` targets Python 2.7, 3.4 and newer, and PyPy.
  78. If you need any help, visit us on ``#structlog`` on `Freenode <https://freenode.net>`_!
  79. Release Information
  80. ===================
  81. 17.2.0 (2017-05-15)
  82. -------------------
  83. Backward-incompatible changes:
  84. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  85. *none*
  86. Deprecations:
  87. ^^^^^^^^^^^^^
  88. *none*
  89. Changes:
  90. ^^^^^^^^
  91. - ``structlog.stdlib.ProcessorFormatter`` now accepts *keep_exc_info* and *keep_stack_info* arguments to control what to do with this information on log records.
  92. Most likely you want them both to be ``False`` therefore it's the default.
  93. `#109 <https://github.com/hynek/structlog/issues/109>`_
  94. - ``structlog.stdlib.add_logger_name()`` now works in ``structlog.stdlib.ProcessorFormatter``'s ``foreign_pre_chain``.
  95. `#112 <https://github.com/hynek/structlog/issues/112>`_
  96. - Clear log record args in ``structlog.stdlib.ProcessorFormatter`` after rendering.
  97. This fix is for you if you tried to use it and got ``TypeError: not all arguments converted during string formatting`` exceptions.
  98. `#116 <https://github.com/hynek/structlog/issues/116>`_
  99. `#117 <https://github.com/hynek/structlog/issues/117>`_
  100. `Full changelog <http://www.structlog.org/en/stable/changelog.html>`_.
  101. Authors
  102. =======
  103. ``structlog`` is written and maintained by `Hynek Schlawack <https://hynek.me/>`_.
  104. It’s inspired by previous work done by `Jean-Paul Calderone <http://as.ynchrono.us/>`_ and `David Reid <https://dreid.org/>`_.
  105. The development is kindly supported by `Variomedia AG <https://www.variomedia.de/>`_.
  106. A full list of contributors can be found on GitHub’s `overview <https://github.com/hynek/structlog/graphs/contributors>`_.
  107. Some of them disapprove of the addition of thread local context data. :)
  108. The ``structlog`` logo has been contributed by `Russell Keith-Magee <https://github.com/freakboy3742>`_.