django crontab

dead simple crontab powered job scheduling for django.

kraiz
846
113
Python

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about

dead simple crontab powered job scheduling for django (1.8-2.0).

setup

install via pip:

… code:: bash

pip install django-crontab

add it to installed apps in django settings.py:

… code:: python

INSTALLED_APPS = (
    'django_crontab',
    ...
)

now create a new method that should be executed by cron every 5 minutes, f.e. in myapp/cron.py:

… code:: python

def my_scheduled_job():
  pass

now add this to your settings.py:

… code:: python

CRONJOBS = [
    ('*/5 * * * *', 'myapp.cron.my_scheduled_job')
]

you can also define positional and keyword arguments which let you call django management commands:

… code:: python

CRONJOBS = [
    ('*/5 * * * *', 'myapp.cron.other_scheduled_job', ['arg1', 'arg2'], {'verbose': 0}),
    ('0   4 * * *', 'django.core.management.call_command', ['clearsessions']),
]

finally, run this command to add all defined jobs from CRONJOBS to crontab (of the user which you are running this command with):

… code:: bash

python manage.py crontab add

show current active jobs of this project:

… code:: bash

python manage.py crontab show

removing all defined jobs is straightforward:

… code:: bash

python manage.py crontab remove

config

there are a bunch of setting vars to customize behavior. each of them comes with default values that should properly fit. if not, feel free to overwrite.

CRONJOBS

  • list of jobs, each defined as a tuple:

    • format 1:

      1. required: cron timing in usual format (see Wikipedia <http://en.wikipedia.org/wiki/Cron#Format>_ and crontab.guru <https://crontab.guru/examples.html>_ for more examples)
      2. required: the python module path to the method
      3. optional: a job-specific suffix (f.e. to redirect out/err to a file, default: ‘’)

    • format 2:

      1. required: cron timing
      2. required: the python module path to the method
      3. optional: list of positional arguments for the method (default: [])
      4. optional: dict of keyword arguments for the method (default: {})
      5. optional: a job specific suffix (f.e. to redirect out/err to a file, default: ‘’)

  • NOTE: Run “python manage.py crontab add” each time you change CRONJOBS in any way!

  • default: []

  • example:

    … code:: python

    CRONJOBS = [
    ('*/5 * * * *', 'myapp.cron.my_scheduled_job'),

    # format 1
    ('0   0 1 * *', 'myapp.cron.my_scheduled_job', '>> /tmp/scheduled_job.log'),

    # format 2
    ('0   0 1 * *', 'myapp.cron.other_scheduled_job', ['myapp']),
    ('0   0 * * 0', 'django.core.management.call_command', ['dumpdata', 'auth'], {'indent': 4}, '> /home/john/backups/last_sunday_auth_backup.json'),
]

CRONTAB_LOCK_JOBS

  • prevent starting a job if an old instance of the same job is still running
  • default: False
  • since 0.5.0

CRONTAB_EXECUTABLE

  • path to the crontab executable of your os
  • default: ‘/usr/bin/crontab’

CRONTAB_DJANGO_PROJECT_NAME

  • the name of your django project, used to build path path to manage.py and to mark the jobs in crontab via comment for later removing
  • default is read from DJANGO_SETTINGS_MODULE environment variable

CRONTAB_DJANGO_MANAGE_PATH

  • path to manage.py file (including the manage.py itself, i.e. ‘/home/john/web/manage.py’)
  • default is build using DJANGO_PROJECT_NAME

CRONTAB_DJANGO_SETTINGS_MODULE

  • dotted python path to the settings module to run the command with
  • default is the common one from the environment variable and will not be overwritten
  • since 0.6.0

CRONTAB_PYTHON_EXECUTABLE

  • path to the python interpreter executable used to run the scheduled job
  • default uses the interpreter executable used to add the jobs (via ‘python manage.py crontab add’)

CRONTAB_COMMAND_PREFIX

  • something you want to do or declare, before each job gets executed. A good place for environment variables.
  • default: ‘’ (empty string)
  • example: ‘STAGE=production’

CRONTAB_COMMAND_SUFFIX

  • something you want to do after each job was executed.
  • default: ‘’ (empty string)
  • example: ‘2>&1’

CRONTAB_COMMENT

  • used for marking the added contab-lines for removing, default value includes project name to distinguish multiple projects on the same host and user
  • default: 'django-crontabs for ’ + CRONTAB_DJANGO_PROJECT_NAME

contributors

arski cinghiale meric426 justdoit0823 chamaken

faq

  • I’m using this old django version (<1.8) and can’t install this package. What should i do?

    • Yeah, update django of course (!) or - as you seem to be familiar with old, unsupported versions, install the old version of this package too (it support django 1.3-1.7)::

      pip install django-crontab==0.6.0

  • Will it work with windows?

    • No.

  • Will it work within a docker?

    • Not immediately, you need to start the cron service.

  • Problems with pyenv?

    • You maybe need to setup the PATH variable within crontab. Have a look at #60 </../../issues/60>_

  • I’m getting “bad command”/“errors in cronfile” while installing via “crontab add”. What’s wrong?

    • Maybe it’s your cron time format, it can have 5 or 6 fields. Check that your system supports 6 or just define 5 in CRONJOBS. (see #23)

  • Why does the LOGGING not work when started via cronjob?

    • That’s maybe something about the current working dir. Please set your FileHandler’s file path absolute and try again. (see #31 </../../issues/31>_)

license

MIT-License, see LICENSE file.