Versions follow CalVer with a strict backwards compatibility policy.
Put simply, you shouldn’t ever be afraid to upgrade
structlog if you’re using its public APIs.
Whenever there is a need to break compatibility, it is announced here in the changelog, and raises a
DeprecationWarning for a year (if possible) before it’s finally really broken.
You cannot rely on the default settings and the
They may be adjusted in the future to provide a better experience when starting to use
So please make sure to always properly configure your applications.
structlogswitched its packaging to flit. Users shouldn’t notice a difference, but (re-)packagers might.
sort_keysboolean parameter that allows to disable the sorting of keys on output. #358
structlog.processors.TimeStampernow works well with FreezeGun even when it gets applied before the loggers are configured. #364
structlog.stdlib.AsyncBoundLoggernow determines the running loop when logging, not on instantiation. That has a minor performance impact, but makes it more robust when loops change (e.g.
aiohttp.web.run_app()), or you want to use
sync_blbefore a loop has started.
structlog.stdlib.ProcessorFormatternow has a processors argument that allows to define a processor chain to run over all log entries.
Before running the chain, two additional keys are added to the event dictionary:
_from_structlog. With them it’s possible to extract information from
logging.LogRecords and differentiate between
logginglog entries while processing them.
The old processor (singular) parameter is now deprecated, but no plans exist to remove it. #365
To implement pretty exceptions (see Changes below),
structlog.dev.ConsoleRenderernow formats exceptions itself.
Make sure to remove
format_exc_infofrom your processor chain if you configure
structlogmanually. This change is not really breaking, because the old use-case will keep working as before. However if you pass
pretty_exceptions=True(which is the default if either
better-exceptionsis installed), a warning will be raised and the exception will be renderered without prettyfication.
structlogis now importable if
None(e.g. when running using
structlog.contextvars.get_contextvars()can now be used to get a copy of the current thread-local/context-local context that has been bound using
structlog.contextvars.bind_contextvars(). #331 #337
structlog.contextvars.get_merged_contextvars(bl)do the same, but also merge the context from a bound logger bl. Same pull requests as previous change.
structlog.contextvars.bind_contextvars()now returns a mapping of keys to
contextvars.Tokens, allowing you to reset values using the new
Exception rendering in
structlog.dev.ConsoleLoggeris now configurable using the
exception_formattersetting. If either the rich or the better-exceptions package is present,
structlogwill use them for pretty-printing tracebacks.
richtakes precedence over
better-exceptionsif both are present.
All use of
coloramaon non-Windows systems has been excised. Thus, colors are now enabled by default in
structlog.dev.ConsoleRendereron non-Windows systems. You can keep using
coloramato customize colors, of course. #345
The final processor can now return a
Python 2.7 and 3.5 aren’t supported anymore. The package meta data should ensure that you keep getting 20.1.0 on those versions. #244
structlogis now fully type-annotated. This won’t break your applications, but if you use Mypy, it will most likely break your CI.
Check out the new chapter on typing for details.
The default bound logger (
wrapper_class) if you don’t configure
structloghas changed. It’s mostly compatible with the old one but a few uncommon methods like
errdon’t exist anymore.
You can regain the old behavior by using
Please note that due to the various interactions between settings, it’s possible that you encounter even more errors. We strongly urge you to always configure all possible settings since the default configuration is not covered by our backward compatibility policy.
_contextattribute of a bound logger is now deprecated. Please use the new
structloghas now type hints for all of its APIs! Since
structlogis highly dynamic and configurable, this led to a few concessions like a specialized
structlog.stdlib.get_logger()whose only difference to
structlog.get_logger()is that it has the correct type hints.
We consider them provisional for the time being – i.e. the backward compatibility does not apply to them in its full strength until we feel we got it right. Please feel free to provide feedback! #223, #282
structlog.make_filtering_loggerthat can be used like
configure(wrapper_class=make_filtering_bound_logger(logging.INFO)). It creates a highly optimized bound logger whose inactive methods only consist of a
return None. This is now also the default logger.
As a complement,
structlog.stdlib.add_log_level()can now additionally be imported as
structlog.processors.add_log_levelsince it just adds the method name to the event dict.
structlog.processors.add_log_level()is now part of the default configuration.
structlog.stdlib.ProcessorFormatterno longer uses exceptions for control flow, allowing
foreign_pre_chainprocessors to use
sys.exc_info()to access the real exception.
structlog.BytesLoggerto avoid unnecessary encoding round trips. Concretely this is useful with orjson which returns bytes. #271
The final processor now also may return bytes that are passed untouched to the wrapped logger.
structlog.get_context()allows you to retrieve the original context of a bound logger. #266,
structlog.testing.CapturingLoggerfor more unit testing goodness.
structlog.stdlib.AsyncBoundLoggerthat executes logging calls in a thread executor and therefore doesn’t block. #245
This is the last version to support Python 2.7 (including PyPy) and 3.5. All following versions will only support Python 3.6 or later.
The logger created by
structlog.get_logger()is not detected as an abstract method anymore, when attached to an abstract base class. #229
Python 3.4 is not supported anymore. It has been unsupported by the Python core team for a while now and its PyPI downloads are negligible.
It’s very unlikely that
structlogwill break under 3.4 anytime soon, but we don’t test it anymore.
Full Python 3.8 support for
Added more pass-through properties to
structlog.stdlib.BoundLogger. To makes it easier to use it as a drop-in replacement for
structlog.stdlib.ProcessorFormatternow takes a logger object as an optional keyword argument. This makes
ProcessorFormatterwork properly with
structlog.dev.ConsoleRenderernow uses no colors by default, if
coloramais not available. #215
coloramalazily, to prevent accidental side-effects just by importing
Added new processor
structlog.dev.set_exc_info()that will set
exc_info=Trueif the method’s name is
exc_infoisn’t set at all. This is only necessary when the standard library integration is not used. It fixes the problem that in the default configuration,
exceptblock would not print the exception without passing
exc_info=Trueto it explicitly. #130, #173, #200, #204
A best effort has been made to make as much of
structlogpickleable as possible to make it friendlier with
multiprocessingand similar libraries. Some classes can only be pickled on Python 3 or using the dill library though and that is very unlikely to change.
So far, the configuration proxy,
structlog.dev.ConsoleRendererhave been made pickelable. Please report if you need any another class fixed. #126
structlog.stdlib.ProcessorFormatter. It allows to pass a foreign log record’s
argsattribute to the event dictionary under the
str()on the event value. #221
As announced in 18.1.0,
pip install -e .[dev]now installs all development dependencies. Sorry for the inconveniences this undoubtedly will cause!
structlog.PrintLoggernow have a
fatal()log method. #181
Under certain (rather unclear) circumstances, the frame extraction could throw an
SystemError: error return without exception set. A workaround has been added. #174
structlog.stdlib.add_log_level_number()processor that adds the level number to the event dictionary. Can be used to simplify log filtering. #151
try_unbind()that works like
unbind()but doesn’t raise a
KeyErrorif one of the keys is missing. #171
The meaning of the
structlog[dev]installation target will change from “colorful output” to “dependencies to develop
structlog” in 19.1.0.
The main reason behind this decision is that it’s impossible to have a
structlogin your normal dependencies and additionally a
structlog[dev]for development (
pipwill report an error).
Empty strings are valid events now. #110
Do not encapsulate Twisted failures twice with newer versions of Twisted. #144
structlog.dev.ConsoleRenderernow accepts a force_colors argument to output colored logs even if the destination is not a tty. Use this option if your logs are stored in files that are intended to be streamed to the console.
structlog.dev.ConsoleRenderernow accepts a level_styles argument for overriding the colors for individual levels, as well as to add new levels. See the docs for
ConsoleRenderer.get_default_level_styles()for usage. #139
structlog.stdlib.BoundLogger.exception()now uses the
exc_infoargument if it has been passed instead of setting it unconditionally to
Default configuration now uses plain
dicts on Python 3.6+ and PyPy since they are ordered by default.
structlog.is_configured()to check whether or not
structloghas been configured.
structlog.get_config()to introspect current configuration.
structlog.stdlib.ProcessorFormatternow accepts keep_exc_info and keep_stack_info arguments to control what to do with this information on log records. Most likely you want them both to be
Falsetherefore it’s the default. #109
structlog.stdlib.add_logger_name()now works in
Clear log record args in
structlog.stdlib.ProcessorFormatterafter rendering. This fix is for you if you tried to use it and got
TypeError: not all arguments converted during string formattingexceptions. #116, #117
The main features of this release are massive improvements in standard library’s
Have a look at the updated standard library chapter on how to use them!
Special thanks go to
that made them possible.
The default renderer now is
structlog.dev.ConsoleRendererif you don’t configure
structlog. Colors are used if available and human-friendly timestamps are prepended. This is in line with our backward compatibility policy that explicitly excludes default settings.
structlog.stdlib.render_to_log_kwargs(). This allows you to use
logging-based formatters to take care of rendering your entries. #98
UNIX epoch timestamps from
structlog.processors.TimeStamperare more precise now.
Added repr_native_str to
structlog.dev.ConsoleRenderer. This allows for human-readable non-ASCII output on Python 2 (
repr()on Python 2 behaves like
ascii()on Python 3 in that regard). As per compatibility policy, it’s on (original behavior) in
KeyValueRendererand off (humand-friendly behavior) in
Added colors argument to
structlog.dev.ConsoleRendererand made it the default renderer. #78
Fixed bug with Python 3 and
structlog.stdlib.BoundLogger.log(). Error log level was not reproductible and was logged as exception one time out of two. #92
Positional arguments are now removed even if they are empty. #82
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.
key_orderis used and a key is missing a value, it’s not rendered at all instead of being rendered as
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
structlog.processors.format_exc_infonow support passing of Exceptions on Python 3.
Clean up the context when exiting
structlog.threadlocal.tmp_bindin case of exceptions. #64
Be more more lenient about missing
structlog.dev.ConsoleRendererthat renders the event dictionary aligned and with colors.
Use six for compatibility.
structlog.processors.UnicodeDecoderthat will decode all byte string values in an event dictionary to Unicode.
structlog.processors.JSONRendererwhich allows for using different (possibly faster) JSON encoders than the standard library.
Tolerate frames without a
__name__, better. #58
Officially support Python 3.5.
structlog.PrintLogger.failureas preparation for the new Twisted logging system.
Allow empty lists of processors. This is a valid use case since #26 has been merged. Before, supplying an empty list resulted in the defaults being used.
log.errfrom quoting strings rendered by
Better support of
Add option to specify target key in
Tolerate frames without a
Pass positional arguments to stdlib wrapped loggers that use string formatting. #19
Fixed a memory leak in greenlet code that emulates thread locals. It shouldn’t matter in practice unless you use multiple wrapped dicts within one program that is rather unlikely. #8
structlog.PrintLoggernow is thread-safe.
Test Twisted-related code on Python 3 (with some caveats).
Drop support for Python 3.2. There is no justification to add complexity for a Python version that nobody uses. If you are one of the 0.350% that use Python 3.2, please stick to the 0.4 branch; critical bugs will still be fixed.
Officially support Python 3.4.
Allow final processor to return a dictionary. See the adapting chapter. #26
from structlog import *works now (but you still shouldn’t use it).
Don’t cache proxied methods in
structlog.threadlocal._ThreadLocalDictWrapper. This doesn’t affect regular users.
Various doc fixes.
structlog.processors.StackInfoRendererfor adding stack information to log entries without involving exceptions. Also added it to default processor chain. #6
Allow optional positional arguments for
structlog.get_loggerthat are passed to logger factories. The standard library factory uses this for explicit logger naming. #12
structlog.processors.ExceptionPrettyPrinterfor development and testing when multiline log entries aren’t just acceptable but even helpful.
Allow the standard library name guesser to ignore certain frame names. This is useful together with frameworks.
Add meta data (e.g. function names, line numbers) extraction for wrapped stdlib loggers. #5
Fix stdlib’s name guessing.
structlog.processors.TimeStamperto API documentation.
Greatly enhanced and polished the documentation and added a new theme based on Write The Docs, requests, and Flask.
Add Python Standard Library-specific BoundLogger that has an explicit API instead of intercepting unknown method calls. See
structlog.ReturnLoggernow allows arbitrary positional and keyword arguments.
Add Twisted-specific BoundLogger that has an explicit API instead of intercepting unknown method calls. See
Allow logger proxies that are returned by
structlog.wrap_loggerto cache the BoundLogger they assemble according to configuration on first use. See the chapter on performance and the
Extract a common base class for loggers that does nothing except keeping the context state. This makes writing custom loggers much easier and more straight-forward. See
Promote to stable, thus henceforth a strict backward compatibility policy is put into effect.
structlog.processors.KeyValueRendererfor more predictable log entries with any
structlog.PrintLoggernow uses proper I/O routines and is thus viable not only for examples but also for production.
Enhance Twisted support by offering JSONification of non-structlog log entries.
Allow for custom serialization in