How do you deploy cron jobs to production?

Question

How do people deploy/version control cronjobs to production? I'm more curious about conventions/standards people use than any particular solution, but I happen to be using git for revision control, and the cronjob is running a python/django script.

Answer 1

If you are using Fabric for deploment you could add a function that edits your crontab.

def add_cronjob():
    run('crontab -l > /tmp/crondump')             
    run('echo "@daily /path/to/dostuff.sh 2> /dev/null" >> /tmp/crondump')
    run('crontab /tmp/crondump')

This would append a job to your crontab (disclaimer: totally untested and not very idempotent).

1. Save the crontab to a tempfile.

2. Append a line to the tmpfile.

3. Write the crontab back.

This is propably not exactly what you want to do but along those lines you could think about checking the crontab into git and overwrite it on the server with every deploy. (if there's a dedicated user for your project.)

Answer 2

Using Fabric, I prefer to keep a pristine version of my crontab locally, that way I know exactly what is on production and can easily edit entries in addition to adding them.

The fabric script I use looks something like this (some code redacted e.g. taking care of backups):

def deploy_crontab():
    put('crontab', '/tmp/crontab')
    sudo('crontab < /tmp/crontab')