Bare minimum cron job monitoring for the masses.
Cronfed monitors basic batch jobs, or any other cron-based scheduled commands by parsing a given mailbox and turning it into an RSS feed. The feed can in turn be monitored with your browser, feedreader or other RSS-compatible service (such as IFTTT).
Simply add a cron job to generate the feed, pointing it at a web-accessible location (such as a public_html directory or your site’s assets directory). Check out the example for some real-world Cronfed usage, with an explanation of how cron and Cronfed work together.
Cronfed is Minimum Viable Monitoring, aimed at providing a basic threshold of monitoring without complex automation or dependencies. It’s targeted at smaller projects which otherwise might go without any monitoring at all. It’s so easy to set up and use on the standard Linux/BSD machine that there’s no reason to not use it from Day 1. While Cronfed makes attempts at limiting the amount of information externalized, it is not recommended for jobs with extremely-sensitive information.
“Cronfed: It’s the least you could do!”
Cronfed is pure Python, has no system library dependencies, and should work wonders on any POSIX machine with a functioning cron daemon and local mail system:
pip install cronfed
Run python -m cronfed --help to see options, or read on for a usage example.
First, let’s look at a basic cron job. This one will fetch our data once an hour, on the hour:
0 * * * * /usr/bin/python /home/myuser/project/fetch.py 2>&1 | tee -a /home/myuser/project/logs/fetch.txt
Notice how the output (stdout + stderr) is piped to a log file, but using the tee command. This ensures that the output goes to the file as well as stdout. cron captures that stdout and puts it into an email, which then gets sent to the user who owns the job. This usually means the email goes to myuser@localhost, which on many distributions means that it is saved to /var/mail/myuser. Do note that if the command generates no output, then cron will not send an email, so it’s a good idea to emit an error message.
Once we’re sure that email is being delivered, we’re halfway there. Now we just need the actual Cronfed cronjob:
*/15 * * * * /usr/bin/python -m cronfed --output /var/www/mysite/assets/cronfed.rss /var/mail/myuser 2>&1 | tee -a /home/myuser/project/logs/cronfed.txt
In this example we have the installed cronfed module regenerating our feed every fifteen minutes. This is a pretty quick process in most cases, so feel free to make it more often. In this case, the output of cronfed itself is monitored in exactly the same way as normal cron jobs, with a logfile and email to user@localhost.
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