django-serverless-cron 🦡

django-serverless-cron is a Django app with a simpler approach running cron jobs. This is done through exposing a HTTP endpoint to invoke the jobs that allows you to run any task without having to manage always-on infrastructure.

There is also an option to run jobs via management commands and the Django admin.

Why?

This is essentially a replacement/supplement for a traditional OS 'cron' or 'job scheduler' system:

• Serverless cron jobs no-longer a pain. Note that if you have alternatives like django-crontab or celery working well for you, good for you! You probably don't need this. However, it's okay to be curious.
• Schedule jobs to run at a frequency that is less than 1 min. (crontab is limited to 1 min)
• The machine running crontab is no longer a single point of failure.
• The problem with the above systems is that they are often configured at the operating system level, which means their configuration is probably not easily 'portable' and 'debug-able' (if you are developing on Windows, the scheduler works differently from Linux or Unix). Also can not easily be integrated into a development environment.
• Manually triggered cron jobs. Eg: via the Django Admin.
• Alternative to cron services that aren't always available on free (and sometimes paid) web hosting services.
• Easier access to cron job execution logs and monitoring execution failures.
• No need to learn crontab. Think of it as a friendlier alternative to traditional cron jobs. Simple cron job creation. No need for cron syntax, no guessing on job frequency. Easy controls.
• Designed around services like Google Cloud Scheduler and Amazon EventBridge.

Documentation

Documentation is graciously hosted at https://django-serverless-cron.readthedocs.io.

Contributions

Feel free to make pull requests and submit issues/requests. Find more detailed instructions under the contributing section.

Alternatively, you can leave a star on the repo to show your support. 🙂

Quickstart

Installation

Install Django Serverless Cron:

pip install django-serverless-cron

Settings

Add it to your INSTALLED_APPS:

INSTALLED_APPS = (
    # ...
    'django_serverless_cron'
    # ...
)

Add jobs to your settings file:

SERVERLESS_CRONJOBS = [
    # (
    #   '1_hours',                       # frequency (seconds, minutes, hours, days, weeks) -> in this case, every one hour
    #   'mail.jobs.send_mail_function',  # path to task/function functions -> in this case, send_mail_function()
    #   {'kwarg1': 'foo'}                # kwargs passed to the function
    # ),
    (
        '1_days',
        'your_app.services.your_job_function',
        {'kwarg1': 'foo', 'kwarg2': 'bar', "is_bulk": True}
    ),
    (
        '1_hours',
        'mail.jobs.send_mail_function',
        {}                               # job without kwargs
    ),
]

URL patterns

Add the jobs to your URL patterns:

from django_serverless_cron import urls as django_serverless_cron_urls


urlpatterns = [
    # ...
    url(r'^', include(django_serverless_cron_urls))
    #...
]

Migrate

python manage.py migrate

Running Jobs

In Development

Running Jobs through HTTP requests

Call the /run path to run all jobs:

Example:

curl http://localhost:8000/run

or

import requests

x = requests.get('http://localhost:8000/run')

Running Jobs through the management command

This will run the jobs every 30 seconds:

python manage.py serverless_cron_run

You can alternatively add the --single_run='True' option to run the jobs just once.

In Production

Similar to in development, we can call the /run path via fully managed services which are usually ridiculously cheap. Examples:

• https://cloud.google.com/scheduler -> Great feature set, easy to use, reasonable free tier & very cheap.
• https://aws.amazon.com/eventbridge
• https://azure.microsoft.com/en-gb/services/logic-apps formerly https://docs.microsoft.com/en-us/azure/scheduler/scheduler-intro
• https://cron-job.org/en/ -> Absolutely free and open-source: https://github.com/pschlan/cron-job.org
• https://www.easycron.com
• https://cronhub.io
• https://cronless.com -> Has 30 Second Cron Jobs
• https://github.com/features/actions; https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#onschedule -> eg making a HTTP request using curl in a step
• https://www.cronjob.de
• https://zeplo.io
• https://catalyst.zoho.com/help/cron.html
• https://www.cronjobservices.com

Related media

For more learning check out:

• https://dev.to/googlecloud/when-you-re-not-around-trigger-cloud-run-on-a-schedule-53p4 | https://youtu.be/XIwbIimM49Y
• https://aws.amazon.com/blogs/compute/using-api-destinations-with-amazon-eventbridge/
• https://docs.aws.amazon.com/AmazonCloudWatch/latest/events/RunLambdaSchedule.html
• https://www.ibm.com/cloud/blog/how-to-schedule-rest-api-calls-on-ibm-cloud
• https://vercel.com/docs/concepts/solutions/cron-jobs
• cron-like recurring task scheduler design https://stackoverflow.com/a/3980935/10904662
• https://www.dailyhostnews.com/google-cloud-launches-fully-managed-cron-job-scheduler-for-enterprises
• Cloud Scheduler from Fireship https://www.youtube.com/watch?v=WUPEUjvSBW8

Credits

Tools used in rendering this package:

• Cookiecutter
• cookiecutter-djangopackage