A Python logging library with super powers
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README.rst

pygogo: a Python logger with super powers

travis versions pypi

sample pygogo usage

Index

Introduction | Requirements | Motivation | Usage | Installation | Project Structure | Design Principles | Structured Logging | Formatters | Handlers | Scripts | Contributing | License

Introduction

pygogo is a Python logging library and command-line interface with super powers. pygogo leverages the standard Python logging module under the hood, so there's no need to learn yet-another logging library. The default implementation sends all messages to stdout, and any messages at level WARNING or above also to stderr.

With pygogo, you can

  • Log via different handlers depending on the event severity
  • Format log messages as plain text, csv, json, and more..
  • Send logs to stdout, stderr, file, email, sockets, and more..
  • Inter-operate with the standard python logging module
  • and much more...

Requirements

pygogo has been tested and is known to work on Python 2.7, 3.5, and 3.6; PyPy2.7; and PyPy3.5.

Motivation

The standard logging module is great, but requires a ton of boilerplate before you can do anything really interesting with it. I designed pygogo to provide many useful logging use-cases out of the box. A reimplementation of Using LoggerAdapters to impart contextual information is shown below:

import pygogo as gogo

logger = gogo.Gogo(__name__).get_structured_logger(connid='1234')
logger.info('log message')

# Prints the following to stdout

{"message": "log message", "connid": "1234"}

Usage

pygogo is intended to be used either directly as a Python library or from the terminal via the command-line interface.

Library

Examples

Hello World

from pygogo import logger

logger.debug('hello world')
logger.error('hello error')

# Prints the following to `stdout`

hello world
hello error

# Prints the following to `stderr`

hello error

Log based debugging

import pygogo as gogo

def main(verbose=False):
    logger = gogo.Gogo(__name__, verbose=verbose).logger
    logger.debug('I will log to `stdout` only if `verbose` is True')
    logger.info('I will log to `stdout` always')
    logger.warning('I will log to both `stdout` and `stderr` always')

Disabled dual logging

import pygogo as gogo

logger = gogo.Gogo(monolog=True).logger
logger.debug('debug message')
logger.info('info message')
logger.warning('warning message')
logger.error('error message')
logger.critical('critical message')

# Prints the following to `stdout.log` (all messages at level `INFO` or below):

debug message
info message

# Prints the following to `stderr` (messages at level `WARNING` or above):

warning message
error message
critical message

Custom formatter [1]

import logging
import pygogo as gogo

log_format = '%(asctime)s - %(name)s - %(levelname)s - %(message)s'
formatter = logging.Formatter(log_format)

logger = gogo.Gogo(
    'examples.fmt',
    low_hdlr=gogo.handlers.file_hdlr('custom_fmt.log'),
    low_formatter=formatter,
    high_level='error',
    high_formatter=formatter).logger

# Now let's log something!

logger.debug('debug message')
logger.info('info message')
logger.warn('warn message')
logger.error('error message')
logger.critical('critical message')

# Prints the following to `custom_fmt.log` (all messages):

2015-12-18 18:51:30,416 - examples.fmt.base - DEBUG - debug message
2015-12-18 18:51:30,416 - examples.fmt.base - INFO - info message
2015-12-18 18:51:30,416 - examples.fmt.base - WARNING - warn message
2015-12-18 18:51:30,416 - examples.fmt.base - ERROR - error message
2015-12-18 18:51:30,416 - examples.fmt.base - CRITICAL - critical message

# Prints the following to `stderr` (messages at level `ERROR` or above):

2015-12-18 18:51:30,416 - examples.fmt.base - ERROR - error message
2015-12-18 18:51:30,416 - examples.fmt.base - CRITICAL - critical message

Structured logging [2]

import pygogo as gogo

formatter = gogo.formatters.structured_formatter
kwargs = {'low_level': 'info', 'low_formatter': formatter}
logger = gogo.Gogo('examples.structured', **kwargs).logger
extra = {'set_value': set([1, 2, 3]), 'snowman': ''}
logger.info('log message', extra=extra)  # doctest: +ELLIPSIS

# Prints the following to `stdout`:

{"snowman": "\u2603", "name": "examples.structured.base", "level": "INFO", "message": "log message", "time": "2015-12-18 18:52:39", "msecs": 58.973073959350586, "set_value": [1, 2, 3]}

Using Filters to impart contextual information [3]

import logging
import pygogo as gogo

levels = ('DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL')
log_frmt = (
   '%(asctime)-4s %(name)-5s %(levelname)-8s IP: %(ip)-15s User: '
   '%(user)-8s %(message)s')

formatter = logging.Formatter(log_frmt)
going = gogo.Gogo('a', low_formatter=formatter)
a1 = going.get_logger('b.c', ip='123.231.231.123', user='fred')
a2 = going.get_logger('e.f', ip='192.168.0.1', user='sheila')

# Now let's log something!

a1.debug('A debug message')
a1.info('An info %s', 'message')

for level in [getattr(logging, l) for l in levels]:
   name = logging.getLevelName(level)
   a2.log(level, 'A %s msg', name)

# Prints the following to `stdout` (all messages):

2015-12-19 10:12:24,479 a.b.c DEBUG    IP: 123.231.231.123 User: fred     A debug message
2015-12-19 10:12:24,479 a.b.c INFO     IP: 123.231.231.123 User: fred     An info message
2015-12-19 10:12:24,479 a.e.f DEBUG    IP: 192.168.0.1     User: sheila   A DEBUG msg
2015-12-19 10:12:24,479 a.e.f INFO     IP: 192.168.0.1     User: sheila   AN INFO msg
2015-12-19 10:12:24,479 a.e.f WARNING  IP: 192.168.0.1     User: sheila   A WARNING msg
2015-12-19 10:12:24,479 a.e.f ERROR    IP: 192.168.0.1     User: sheila   AN ERROR msg
2015-12-19 10:12:24,479 a.e.f CRITICAL IP: 192.168.0.1     User: sheila   A CRITICAL msg

# Prints the following to `stderr` (messages at level `WARNING` or above):

2015-12-19 10:12:24,479 a.e.f WARNING  IP: 192.168.0.1     User: sheila   A WARNING msg
2015-12-19 10:12:24,479 a.e.f ERROR    IP: 192.168.0.1     User: sheila   AN ERROR msg
2015-12-19 10:12:24,479 a.e.f CRITICAL IP: 192.168.0.1     User: sheila   A CRITICAL msg

Multiple loggers [4]

import pygogo as gogo

going = gogo.Gogo(
    'examples.lggrs',
    low_hdlr=gogo.handlers.file_hdlr('multi_lggrs.log'),
    low_formatter=gogo.formatters.fixed_formatter,
    high_level='info',
    high_formatter=gogo.formatters.console_formatter)

root = going.logger
logger1 = going.get_logger('area1')
logger2 = going.get_logger('area2')

# Now let's log something!

root.info('Jackdaws love my big sphinx.')
logger1.debug('Quick zephyrs blow, daft Jim.')
logger1.info('How daft jumping zebras vex.')
logger2.warning('Jail zesty vixen who grabbed pay.')
logger2.error('The five boxing wizards jump.')

# Prints the following to `multi_lggrs.log` (all messages):

2015-12-18 17:21:37.417 examples.lggrs.base INFO     Jackdaws love my big sphinx.
2015-12-18 17:21:37.417 examples.lggrs.area1 DEBUG    Quick zephyrs blow, daft Jim.
2015-12-18 17:21:37.417 examples.lggrs.area1 INFO     How daft jumping zebras vex.
2015-12-18 17:21:37.417 examples.lggrs.area2 WARNING  Jail zesty vixen who grabbed pay.
2015-12-18 17:21:37.417 examples.lggrs.area2 ERROR    The five boxing wizards jump.

# Prints the following to `stderr` (messages at level `INFO` or above):

examples.lggrs.base: INFO     Jackdaws love my big sphinx.
examples.lggrs.area1: INFO     How daft jumping zebras vex.
examples.lggrs.area2: WARNING  Jail zesty vixen who grabbed pay.
examples.lggrs.area2: ERROR    The five boxing wizards jump.

Notes

[1]https://docs.python.org/2/howto/logging-cookbook.html#multiple-handlers-and-formatters
[2]https://docs.python.org/2/howto/logging-cookbook.html#implementing-structured-logging
[3]https://docs.python.org/2/howto/logging-cookbook.html#using-filters-to-impart-contextual-information
[4]https://docs.python.org/2/howto/logging-cookbook.html#logging-to-multiple-destinations

Command-line Interface

Examples

Basic Usage

gogo [options] <message>

show help

gogo -h

CLI usage

usage: gogo [options] <message>

description: Logs a given message

positional arguments:
message The message to log (defaults to reading from stdin).
optional arguments:
-h, --help show this help message and exit
-l LEVEL, --msg-level LEVEL
 The level to log the message (default: info). Must be one of: critical, error, warning, info, debug.
-n NAME, --name NAME
 The logger name (default: pygogo)
-D HANDLER, --high-hdlr HANDLER
 The high pass log handler (default: stderr). Must be one of: buffered, email, file, fileobj, socket, stderr, stdout, syslog, webhook.
-d HANDLER, --low-hdlr HANDLER
 The low pass log handler (default: stdout). Must be one of: buffered, email, file, fileobj, socket, stderr, stdout, syslog, webhook.
-L LEVEL, --high-level LEVEL
 Min level to log to the high pass handler (default: warning). Must be one of: buffered, email, file, fileobj, socket, stderr, stdout, syslog, webhook.
-e LEVEL, --low-level LEVEL
 Min level to log to the low pass handler (default: debug). Must be one of: buffered, email, file, fileobj, socket, stderr, stdout, syslog, webhook.
-F FORMAT, --high-format FORMAT
 High pass handler log format (default: basic). Must be one of: basic, bom, console, csv, fixed, json, structured.
-o FORMAT, --low-format FORMAT
 Low pass handler log format (default: basic). Must be one of: basic, bom, console, csv, fixed, json, structured.
-m, --monolog Log high level events only to high pass handler.
-f FILENAME, --filename FILENAME
 The filename to log to. Required for the follow handlers: file.
-s SUBJECT, --subject SUBJECT
 The log subject (default: You've got mail). Used in the follow handlers: email.
-u URL, --url URL
 The log url. Required for the follow handlers: webhook.
-H HOST, --host HOST
 The host. Used in the follow handlers: socket and syslog.
-p NUM, --port NUM
 The port number. Used in the follow handlers: socket and syslog.
-t, --tcp Use TCP instead of UDP. Used in the follow handlers: socket and syslog.
-g, --get Use a GET request instead of POST. Used in the follow handlers: webhook.
-v, --version Show version and exit.
-V, --verbose Increase output verbosity.

Hello World

gogo 'hello world'

Log based debugging

gogo 'default info level will log to `stdout`'
gogo --level=debug "debug won't log"
gogo --level=debug -V 'verbose will log to `stdout`'
gogo --level=info 'info will log to `stdout`'
gogo --level=warning 'warning will log to both `stdout` and `stderr`'

# Prints the following to `stdout`:

default info level will log to `stdout`
verbose will log to `stdout`
info will log to `stdout`
warning will log to both `stdout` and `stderr`

# Prints the following to `stderr`:

warning will log to both `stdout` and `stderr`

Disable dual logging

gogo --level=debug -V 'debug message'
gogo --level=info 'info message'
gogo --level=warning -m 'warning message'
gogo --level=error -m 'error message'
gogo --level=critical -m 'critical message'

# Prints the following to `stdout.log` (all messages at level `INFO` or below):

debug message
info message

# Prints the following to `stderr` (messages at level `WARNING` or above):

warning message
error message
critical message

Structured logging

gogo --low-format=json 'log message'

# Prints the following to `stdout`:

{"time": "2015-12-19 11:26:53.776", "name": "pygogo.runner", "level": "INFO", "message": "log message"}

Alternate handler

gogo --low-hdlr=file 'log message'

# Prints the following to `pygogo.log` in the current dir (assuming the current dir is named `pygogo`):

{"time": "2015-12-19 11:26:53.776", "name": "pygogo.runner", "level": "INFO", "message": "log message"}

Installation

(You are using a virtualenv, right?)

At the command line, install pygogo using either pip (recommended)

pip install pygogo

or easy_install

easy_install pygogo

Please see the installation doc for more details.

Project Structure

┌── bin
│   └── gogo
├── docs
│   ├── AUTHORS.rst
│   ├── CHANGES.rst
│   ├── INSTALLATION.rst
│   └── TODO.rst
├── helpers
│   ├── check-stage
│   ├── clean
│   ├── pippy
│   ├── srcdist
│   └── wheel
├── pygogo
│   ├── __init__.py
│   ├── formatters.py
│   ├── handlers.py
│   ├── main.py
│   └── utils.py
├── tests
│   ├── __init__.py
│   ├── standard.rc
│   ├── test.py
│   └── test_main.py
├── CONTRIBUTING.rst
├── LICENSE
├── MANIFEST.in
├── Makefile
├── README.rst
├── dev-requirements.txt
├── examples.py
├── manage.py
├── py2-requirements.txt
├── setup.cfg
├── setup.py
└── tox.ini

Design Principles

  • the built-in logging module isn't broken so don't reinvent the wheel
  • prefer functions over objects
  • keep the API as simple as possible

Structured Logging

There are severals ways to get structured (machine readable) log messages using pygogo. Each method makes a different customization/complexity trade-off which is outlined below:

Setup

The following methods make use of these variables.

import pygogo as gogo

kwargs = {'contextual': True}
extra = {'additional': True}

Methods

basic structured logger

The simplest to use. Useful if you don’t need message metadata, i.e., log level, log name, and log time.

logger = gogo.Gogo('basic').get_structured_logger('base', **kwargs)
logger.debug('message', extra=extra)

# Prints the following to `stdout`:

{"additional": true, "contextual": true, "message": "message"}

structured formatter

Requires an additional step of specifying a formatter. Useful if you need message metadata, i.e., log level, log name, and log time.

formatter = gogo.formatters.structured_formatter
logger = gogo.Gogo('struct', low_formatter=formatter).get_logger(**kwargs)
logger.debug('message', extra=extra)

# Prints the following to `stdout`:

 {"additional": true, "contextual": true, "level": "DEBUG", "message": "message", "msecs": 760.5140209197998, "name": "struct.base", "time": "2015-12-19 14:25:58"}

JSON formatter

Requires an additional step of specifying a formatter. Useful if you require millisecond precision in the date. If you are ok with having the milliseconds in a separate field, consider the structured formatter since it supports the extra keyword and contextual information.

formatter = gogo.formatters.json_formatter
logger = gogo.Gogo('json', low_formatter=formatter).get_logger(**kwargs)
logger.debug('message', extra=extra)

# Prints the following to `stdout`:

{"level": "DEBUG", "message": "message", "name": "json.base", "time": "2015-12-19 14:25:58.760"}

# Note that both `extra` and `kwargs` were ignored

custom logger

The most complex and customizable. Useful if you need a custom log or date format not provided by the above methods. However, even though this method supports the extra keyword when logging, it is static (unlike the structured logger or structured formatter). This is because the log format must be specified at the time of the log's creation and therefore can't adapt to log messages with differing extra parameters.

logfmt = (
    '{"time": "%(asctime)s.%(msecs)d", "name": "%(name)s", "level":'
    ' "%(levelname)s", "message": "%(message)s", '
    '"contextual": "%(contextual)s", "additional": "%(additional)s"}')

fmtr = logging.Formatter(logfmt, datefmt=gogo.formatters.DATEFMT)
logger = gogo.Gogo('custom', low_formatter=fmtr).get_logger(**kwargs)
logger.debug('message', extra=extra)

# Prints the following to `stdout`:

{"additional": "True", "contextual": "True", "level": "DEBUG", "message": "message", "name": "custom.logger", "time": "2015-12-19 14:25:58.760"}

Summary

The following table can help make sense of the different methods:

  structured logger structured formatter json formatter custom logger
contextual information  
extra param support  
dynamic extra support    
message metadata  
available via the command line    
msecs field      
milliseconds in time field    
custom date format      
custom log format      

Formatters

pygogo has several builtin formatters and also supports any logging.Formatter instance.

Examples

builtin CSV format in python

import pygogo as gogo

formatter = gogo.formatters.csv_formatter
gogo.Gogo('csv', low_formatter=formatter).logger.debug('message')

# Prints the following to `stdout`:

2015-12-19 17:03:48.99,csv.base,DEBUG,"message"

logging.Formatter instance in python

import logging
import pygogo as gogo

datefmt = gogo.formatters.DATEFMT
formatter = logging.Formatter(gogo.formatters.CSV_FORMAT, datefmt=datefmt)
gogo.Gogo('csv', low_format=formatter).get_logger('custom').debug('message')

# Prints the following to `stdout`:

2015-12-19 17:03:48.99,csv.custom,DEBUG,"message"

builtin CSV format via CLI

gogo --low-format=csv 'message'

# Prints the following to `stdout`:

2015-12-19 15:51:32.16,pygogo.runner,INFO,"message"

Summary

The following table can help make sense of the different builtin formatters:

name message
basic message
bom message
console name: INFO message
csv 2015-12-19 15:51:32.16,name,INFO,"message"
fixed 2015-12-19 15:51:32.16 name INFO message
json {"level": "INFO", "message": "message", "name": "name", "time": "2015-12-19 15:51:32.16"}
structured {"level": "INFO", "message": "message", "msecs": 16.5140209197998, "name": "name", "time": "2015-12-19 15:51:32"}

Handlers

pygogo has several builtin handlers and also supports any instance from the logging.handlers module.

Examples

builtin stdout handler in python

import pygogo as gogo

hdlr = gogo.handlers.stdout_hdlr()
gogo.Gogo('stdout', low_hdlr=hdlr).logger.debug('message')

# Prints 'message' to `stdout`

logging.StreamHandler instance in python

import logging
import sys
import pygogo as gogo

hdlr = logging.StreamHandler(sys.stdout)
gogo.Gogo('stdout', low_hdlr=hdlr).get_logger('custom').debug('message')

# Prints 'message' to `stdout`

builtin CSV format via CLI

gogo --low-hdlr=stdout 'message'

# Prints 'message' to `stdout`

Summary

The following table can help make sense of the different builtin handlers:

name description
buffered Holds log in memory until it reaches its capacity, or it logs a message with a level at or above the flush level
email Emails log to a given email address
file Writes log to a given filename
fileobj Writes log to a given file-like object
socket Writes log to a given network socket
stderr Writes log to standard error
stdout Writes log to standard output
syslog Writes log to syslog
webhook POSTs log to a url

Scripts

pygogo comes with a built in task manager manage.py

Setup

pip install -r dev-requirements.txt

Examples

Run python linter and nose tests

manage lint
manage test

Contributing

Please mimic the coding style/conventions used in this repo. If you add new classes or functions, please add the appropriate doc blocks with examples. Also, make sure the python linter and nose tests pass.

Please see the contributing doc for more details.

License

pygogo is distributed under the MIT License.