Skip to main content

Tag-based logging for Python 3.

Project description

Tag-based logging library for Python 3.

This logging library is based on the following concepts (partially inspired by the twelve-factor app):

  • All output is written unbuffered to stdout. (There are no handlers.)
  • The application controls the output in a print()-style syntax. (There are no formatters.)
  • Output lines are tagged and the actual output can be filtered by tags. (There are no log levels.)
  • All configuration is taken from environment variables. (There are no configuration files.)
  • All logging to the standard logging library is redirected to this library. (We are greedy.)

Tagging mechanism

  • Every log output is tagged with a set of implicitly assigned or explicitly specified tags.
  • Explicit tags are specified in a list as optional first parameter of log methods e.g.[‘tag’], …)
  • Implicit tags are:
    • The name of the module that contains the log statement.
    • The name used as log method e.g. log.warning(). Note: There are no pre-defined log methods. Any valid method name if possible e.g. log.whatever() or log.this_too().
    • In case of logging redirected from the standard library:
      • The log level name in lowercase.
      • The name of the logger e.g. ‘root’ for the root logger.


The actual log output is filtered by a list of included or excluded tags. If an include list is specified, only those logs are printed of which at least one tag is part of the include list. If an exclude list is specified, only those logs are printed of which no tag is part of the exclude list. If no list is specified, all logs are printed. If both lists are specified, the exclude list has priority.

Hint: To omit all log output, specify an include list with an unused tag e.g. LOG_INCLUDE=_nothing


$ pip install rlib-log

Getting Started

$ LOG_INCLUDE = debug;some_tag
from rlog import log

log.debug('How many fingers:', 10)
log.something(['some_tag'], 'Output something with additional tag.')

Configuration / environment variables

LOG_FTIME = “%x %X.%f” (default) | <strftime-style format for the time>

LOG_OUTPUT = native (default) | json The JSON-formatted output line is a dict with the following fields: - time: a float value of the timestamp (see datetime.timestamp()) - tags: a list of the log tags - args: a list of the positional arguments - kwargs: a dict of the keyword arguments - exception (optional): a tuple if exception info if that was available during logging

LOG_INCLUDE = <;-separated list of tags to be included in output>

LOG_EXCLUDE = <;-separated list of tags to be excluded from output>

LOG_LOGGING_LEVEL = DEBUG (default) | <level name for standard logging redirect>

LOG_THREADED = false (default) | true When threaded log is enabled, log output is done within a daemon thread that is started during module import.


“MIT”. See LICENSE for details. Copyright, 2018.

Project details

Release history Release notifications | RSS feed

This version


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Files for rlib-log, version 0.1
Filename, size File type Python version Upload date Hashes
Filename, size rlib-log-0.1.tar.gz (5.2 kB) File type Source Python version None Upload date Hashes View

Supported by

AWS AWS Cloud computing Datadog Datadog Monitoring Facebook / Instagram Facebook / Instagram PSF Sponsor Fastly Fastly CDN Google Google Object Storage and Download Analytics Huawei Huawei PSF Sponsor Microsoft Microsoft PSF Sponsor NVIDIA NVIDIA PSF Sponsor Pingdom Pingdom Monitoring Salesforce Salesforce PSF Sponsor Sentry Sentry Error logging StatusPage StatusPage Status page