prolog

Tools and convenience methods to simplify and expedite Python logging.

• Simple - though opinionated - setup for common use-cases
• Extensively and easily configurable via user and local files, as well as environ variables
• Comes with full featured formatters and handlers that can also be used in normal logging situations

Usage

basic_config

The easiest way to begin using prolog is to add the following to your application code:

import prolog
prolog.basic_config()

This will configure the root logger for the default level logging.INFO and set up two handlers: a colorized, console streaming handler, as well as a file handler set to log to the default file - pypro.log - in the main app's directory.

To specify select loggers defined in application or library code, you pass the comma-seperated names of the desired loggers:

prolog.basic_config('myapp,another_app')

basic_config accepts the following parameters:

loggers

The desired loggers to configure; can be either a comma-separated string of logger names, a list of Logger instances, or None for the root logger.

level

Specify the logging level for all loggers and handlers. Can be either the numeric value or string name for the desired level.

handlers

The handlers to add to the given loggers; can be a comma-separated string of shortcut names ('stream' or 'file', by default) or a list of Handler instances.

propagate

Indicates whether each logger instance will be set to propagte.

reset_handlers

If True, force a reset of all currently configured handlers.

cfg

The prolog.config.PrologConfig instance to use. If not given, the default will be used (prolog.config.config). For all preceding parameters except for loggers set to None (the default), cfg will be used to determine the appropriate setting.

Examples

Once installed, prolog can be invoked to show configuration settings or sample usage:

$ python -m prolog sample --level=DEBUG basic

Setting colors via environments variables:

$ export PYPROLOG_LEVEL_COLORS='CRITICAL:white,red;ERROR:lightred;DEBUG:lightgray,cyan;*:gray,gray'
$ python -m prolog sample --level=DEBUG basic

Develop and testing

$ pip install invoke
$ inv develop
$ inv test

Configuration

Prolog can be configured via a number of different options:

• User-level configuration file, using appdirs to determine the user's configuration directory plus pyprolog/config, which must be a JSON encoded file containing a dictionary overriding any of the defaults listed below
• Current working directory configuration file .pyprologrc, also JSON
• Environment variables, see below
• Manipulation of the default prolog.config.config instance or instantiating your own
• Generating a logging.config.dictConfig dict via prolog.config.dict_config

Defaults

LEVEL = 'INFO'
SHORT_FMT = "{levelname}:{name} {message}"
LONG_FMT = '[{asctime} {name}:{levelname}:{module}:{lineno}] {message}'

COLOR_LONG_FMT = '{color}[{asctime} {name}:{levelname}:{module}:{lineno}]{endcolor} {message}'
COLOR_SHORT_FMT = '{color}{levelname}:{name}{endcolor} {message}'
LEVEL_COLORS = 'DEBUG:magenta;INFO:blue;WARNING:yellow;ERROR:red;CRITICAL:white,red'

DATE_FMT = "%Y-%m-%dT%H:%M:%S"
STYLE_FMT = '{'

HANDLERS = 'stream,file'
PROPAGATE = False
DISABLE_EXISTING = True
RESET_HANDLERS = True

STREAM_LEVEL = 'NOTSET'
STREAM_FORMATTER = 'color'
STREAM_STREAM = 'sys.stderr'

FILE_LEVEL = 'NOTSET'
FILE_FORMATTER = 'long'
FILE_FILENAME = 'pypro.log'
FILE_MAX_BYTES = 0
FILE_BACKUP_COUNT = 0

Environment

By default, the prolog.config.config instance will load any environment variable begging with PYPROLOG_ and ending with any of the defaults listed above. For instance, to override the default logging level, do the following before executing your application code:

$ export PYPROLOG_LEVEL='DEBUG'
$ python myapp.py