Logging

pytiger uses the Python logging framework to generate messages and bubble them up through to handlers.

Quick Start

The following snippet will cater for most simple uses:

>>> import logging
>>> import pytiger.logging.config
>>> pytiger.logging.config.basic_config(level=logging.WARNING)
>>> log = logging.getLogger(__name__)
>>> log.info('This entry will not appear')
>>> log.warning('Unable to biggle')
W: Unable to biggle
>>> log.error('Abandon ship, all ye who run this')
E: Abandon ship, all ye who run this

pytiger.logging.config – Configure Python logging

Added in version 1.2.0.

Configure the Python logging system following Tiger conventions.

Example usage:

>>> import logging
>>> import pytiger.logging.config
>>> pytiger.logging.config.basic_config()
>>> log = logging.getLogger(__name__)
>>> log.warning('Unable to biggle')
W: Unable to biggle
>>> log.error('Abandon ship, all ye who run this')
E: Abandon ship, all ye who run this

class pytiger.logging.config.LevelTagFilter

Log filter that adds the leveltag field.

This logging.Filter sub-class (using duck-typing) is used to add the leveltag field to logging.LogRecord objects so that the tag is available for use when formatted with the TCL_FORMAT format string.

pytiger.logging.config.TCL_FORMAT = '%(leveltag)s: %(message)s'

Log format string following Tiger Computing conventions.

pytiger.logging.config.basic_config(fmt=None, datefmt=None, level=None, stderr=True, stderr_level=None, syslog=True, syslog_level=None)

Perform basic configuration of the Python logging system.

This is very similar to logging.basicConfig() but designed to follow Tiger Computing’s logging conventions: messages are logged to stderr and to syslog, and messages are prefixed with a single character tag describing the log level.

This function does nothing if the root logger already has handlers configured, therefore this function will only configure logging once. It is a convenience method to do one-shot configuration of the Python logging package.

The default behaviour is to:

• Create a logging.StreamHandler which writes to sys.stderr.

• Create a pytiger.logging.syslog.SyslogHandler, which forwards messages to syslog using syslog.syslog().

• Add the LevelTagFilter to the above handlers.

• Set a formatter on the above handlers using the TCL_FORMAT format string.

• Add the handlers to the root logger.

• Sets the root logger’s log level to logging.INFO.

Parameters:

• fmt (str) – Use the specified format string for the handlers.

• datefmt (str) – Use the specified date/time format.

• level – Set the root logger’s log level.

• stderr (bool) – Determine whether the stderr StreamHandler is configured or added to the root logger.

• stderr_level – Set the stderr logger’s log level.

• syslog (bool) – Determine whether the SyslogHandler is configured or added to the root logger.

• syslog_level – Set the syslog logger’s log level.

pytiger.logging.syslog – Syslog logging handler

Added in version 1.2.0.

Provides a true syslog handler for the Python logging framework based on the Python syslog module.

pytiger.logging.syslog.FACILITY_NAMES = {'auth': 32, 'cron': 72, 'daemon': 24, 'kern': 0, 'local0': 128, 'local1': 136, 'local2': 144, 'local3': 152, 'local4': 160, 'local5': 168, 'local6': 176, 'local7': 184, 'lpr': 48, 'mail': 16, 'news': 56, 'syslog': 40, 'user': 8, 'uucp': 64}

Mapping of syslog facility names to numeric values

pytiger.logging.syslog.PRIORITY_MAP = [(10, 7), (20, 6), (30, 4), (40, 3), (50, 2)]

Mapping of logging priority levels to syslog priority

pytiger.logging.syslog.PRIORITY_NAMES = {'alert': 1, 'crit': 2, 'debug': 7, 'emerg': 0, 'err': 3, 'info': 6, 'notice': 5, 'warning': 4}

Mapping of syslog priority names to numeric values

class pytiger.logging.syslog.SyslogFormatter(fmt=None, datefmt=None, style='%', validate=True, *, defaults=None)

Default custom formatter for the SyslogHandler.

formatException(ei)

Return a blank string for all exceptions.

This avoids sending exceptions to syslog at any priority.

class pytiger.logging.syslog.SyslogHandler(ident=None, facility=8, options=1, formatter=<class 'pytiger.logging.syslog.SyslogFormatter'>)

Python log handler for syslog.

This uses the Python native syslog module, unlike logging.handlers.SysLogHandler. This means that syslog messages are sent to the local syslog daemon over /dev/log rather than sending UDP messages to localhost (or some remote host).

emit(record)

Emit a record.

pytiger.logging.syslog.encode_priority(fac, pri)

Encode the facility and priority into an integer.

Uses the priority() and facility() functions to look up the values based on the given parameters.

pytiger.logging.syslog.facility(facility)

Lookup a syslog facility number.

Accepts either a string or integer facility. If this is a string, the value is looked up in the FACILITY_NAMES dictionry.

pytiger.logging.syslog.priority(priority)

Lookup a syslog priority level.

Accepts either a string or integer priority level. If this is a string, the value is looked up in the PRIORITY_NAMES dictionry.