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Python logging library is really flexible and powerful but usually, you need some time for setting up the basics or just for logging in a simple script, some commands and settings have to be done. Daiquiri is a library which wrapper python logging library and offers a simple interface for start enjoying logging features in python. Next, there is a hello world example extracted from Daiquiri documentation which shows how easy it gets nice output from the console when you're programming simple scripts.
Celery logs are colorized by default, the first big idea is disable color logs. It’s as easy as setting ‘CELERYD_LOG_COLOR’ to ‘False’ in ‘celery.conf’. The code could be something like this:
celery.conf.update('CELERYD_LOG_COLOR' = False)
Secondly we need a function where we set up a new handler and other settings to celery logging system. For example, the code could be:
from __future__ import absolute_importfrom logging import BASIC_FORMAT, Formatterfrom logging.handlers import SysLogHandlerfrom celery.log import redirect_stdouts_to_loggerdef setup_log(**args): # redirect stdout and stderr to logger redirect_stdouts_to_logger(args['logger']) # logs to local syslog hl = SysLogHandler('/dev/log') # setting log level hl.setLevel(args['loglevel']) # setting log format formatter = Formatter(BASIC_FORMAT) hl.setFormatter(formatter) # add new handler to logger args['logger'].addHandler(hl)
Pay attention to ‘redirect_stdouts_to_logger’ it’s used to send all outputs like print’s or something else to syslog.
Thirdly we want to use those settings in our celery tasks, then we have to connect ‘setup_log’ code to some celery signals. Those signals are launched when ‘task_logger’ and ‘logger’ are configured. To connect signals:
from celery.signals import after_setup_task_logger, after_setup_loggerafter_setup_logger.connect(setup_log)after_setup_task_logger.connect(setup_log)
Fourthly we have to get the ‘logger’, we can have more than one if we are interested in records with task context or without it. For example:
Finally we only have to use those loggers with common methods DEBUG, INFO, WARN, ERROR and CRITICAL:
@celery.taskdef the_task(): logger.info('this is a message without task context') logger_with_task_context.debug('this record will have the prefix "name_of_the_task_to_be_recorded_in_logs" in syslog')
Sovint faig molts scripts de sistema usant python com a llenguatge de programació, doncs bé, sobretot quan aquests scripts s’han de llençar usant el ‘crontab’ va molt bé tenir un bon ‘log’ per saber com van les coses. Així doncs, la setmana passada vaig decidir posar-me a fons amb el tema ‘logging’ de python i ara la forma de fer ‘logs’ que uso per defecte en els meus scripts és:
Després d’importar la llibreria de ‘logging’ es recuperar el fitxer de configuració on estan definits els paràmetres de ‘logging’. Un cop carregat, descomento una o les dues línies que hi ha a continuació en funció de si vull logs per pantalla o només contra un fitxer. La última línia només indica fins a quin nivell de depuració he de fer mostrar logs.
A més vaig trobar un petit script, que carrega una GUI per generar les configuracions dels fitxers de configuració dels ‘logs’, realment útil i simple d’usar:
Aquesta GUI l’he trobada al paquet: logging-0.4.9.6.tar.gz concretament al directori ‘tests’. Si no voleu buscar tant també podeu descarregar-lo directament: logconf.py.
