How to debud django crontab?

Question

I have setup a cron job by using django crontab. As per defined in documentation I defined a test job in cron.py and defined it to run in 1 minute interval in settings.py.

#cron.py
def test_cron_run():
    print("\n\nHello World....!! ",timezone.now())

#settings.py
INSTALLED_APPS = [
    'material.theme.cyan',
    'material',
    'material.admin',
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'myapp',
    'django_crontab',
]

CRONJOBS = [
    ('*/1 * * * *', 'myapp.cron.test_cron_run','>>'+os.path.join(BASE_DIR,'log/debug7.log')),
]

I have added the cron jobs by running python3 manage.py crontab add. Also the job is added as I can see if I run, python3 manage.py crontab show However I cannot see any log file being generated. Is there any way to debug this, the os logs or something?

Phalanx

Is it possible that you're missing a space after the >>? – Headroom

what if using ('*/1 * * * *', 'myapp.cron.test_cron_run', '>> test.log'), instead? – Hysterics

Yes it runs if I run it forcefully by run command passing the hash value of the job and prints on console, however no log file generated, anyway, is there a way I can hook a debugger to my code to debug my django code? – Phalanx

Answer 1

To combine the tips given here, this is how it worked for me:

import os

CRONJOBS = [
    ('* * * * *', 'myapp.cron.test_cron_run', '>> ' + os.path.join(BASE_DIR,'log/debug7.log' + ' 2>&1 '))
]

Additional notes

• The directory needs to exist and you need write permission
• After each change of CRONJOBS, run python3 manage.py crontab add twice
• Without the 2>&1, error messages from python are not logged as they are written to STDERR
• Check what is actually written to your crontab with crontab -l
• If it is not working, you may have a mail from cron. Depending on your system, read it with mail.

Carilyn

Answer 2

Maybe just try adding 2>&1 at the end of you cron job, it will redirect the error output to the standard output.

Cellulosic

Answer 3

I had the same problem. I could only get it to work by including the direct path to the logfile and creating it ahead of time

Pippa

Even though, the file had automatically being created, nothing was being written to it. The solution is as you mentioned to create the file yourself. – Filaria

Answer 4

1. pip install django-crontab
2. Open settings.py file

Now add these lines in your settings.py file

import os
from django.utils.log import DEFAULT_LOGGING
import logging.config

LOG_DIR = os.path.join(BASE_DIR, 'log')
if not os.path.exists(LOG_DIR):
    os.makedirs(LOG_DIR)

LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'formatters': {
        'verbose': {
            'format': '{levelname} {asctime} {module} {message}',
            'style': '{',
        },
    },
    'handlers': {
        'cron_file': {
            'level': 'DEBUG',
            'class': 'logging.FileHandler',
            'filename': os.path.join(LOG_DIR, 'cron_job.log'),
            'formatter': 'verbose',
        },
    },
    'loggers': {
        'student': {
            'handlers': ['cron_file'],
            'level': 'DEBUG',
            'propagate': False,
        },
    },
}

Note: Make sure you have log directory and in your log directory you have file named cron_job.log that defined in loggers settings.

3. Now create file named cron.py in your any app. For example I have app named student and in my app i have file name cron.py file.

Here is my cron.py file code

import logging
from django.utils import timezone
from datetime import timedelta
from student.models import ForgotPasswordAttempt

logger = logging.getLogger('student')


def delete_old_attempts():
    logger.info('Deleting old attempts')
    now = timezone.now()
    time_threshold = now - timedelta(hours=8)

    attempts_to_delete = ForgotPasswordAttempt.objects.filter(
    forgot_password_attempt__gt=5
    ) | ForgotPasswordAttempt.objects.filter(
    updated_at__lt=time_threshold
    )

    count, _ = attempts_to_delete.delete()
    logger.info(f'Deleted {count} ForgotPasswordAttempt objects')

Now Run the these commands in your terminal

# to Add
python manage.py crontab add
# to Show
python manage.py crontab show
# to Remove
python manage.py crontab remove

Emilio