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.
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: