/cf-cron

Run cron jobs and scheduled tasks on Cloud Foundry

MIT LicenseMIT

Running Cron Jobs on Cloud Foundry

This repository demonstrates how to run scheduled tasks on Cloud Foundry with a very small footprint (8 to 16 MB RAM) using a traditional crontab. This means you can run it for a few cents of monthly cost

Traditional cron daemons need to run as root and have opinionated defaults for logging and error notifications. This makes them unsuitable for running in a containerized environment like Cloud Foundry. Instead of a system cron daemon we're thus using supercronic to run our cron tab.

How it works

This application is built using the binary buildpack and executes supercronic on the crontab file. The crontabfile specifies all your cron jobs. To add additional jobs, simply add a new line which specifies a schedule and command to the crontab.

Note: By default, supercronic will log all output to stderr so we redirect that to stdout in our cf manifest.

You can also include additional scripts and binaries to execute more complex actions. This example allows you to install apt and debian packages to use in your cronjobs. You can specify these packages in apt.yml and they will be installed during staging by apt-buildpack courtesy of the magic multi-buildpack.

After cf pushing this sample app to Cloud Foundry, you can see that it happily executes the jobs from the crontab in the log output:

   2018-03-05T10:59:00.00+0100 [APP/PROC/WEB/0] OUT time="2018-03-05T09:59:00Z" level=info msg=starting iteration=237 job.command="echo "hello world, every 2 seconds"" job.position=1 job.schedule="*/2 * * * * * *" 
   2018-03-05T10:59:00.00+0100 [APP/PROC/WEB/0] OUT time="2018-03-05T09:59:00Z" level=info msg="hello world, every 2 seconds" channel=stdout iteration=237 job.command="echo "hello world, every 2 seconds"" job.position=1 job.schedule="*/2 * * * * * *" 
   2018-03-05T10:59:00.00+0100 [APP/PROC/WEB/0] OUT time="2018-03-05T09:59:00Z" level=info msg="job succeeded" iteration=237 job.command="echo "hello world, every 2 seconds"" job.position=1 job.schedule="*/2 * * * * * *" 
   2018-03-05T10:59:00.05+0100 [APP/PROC/WEB/0] OUT time="2018-03-05T09:59:00Z" level=info msg="cf version 6.34.1+bbdf81482.2018-01-17" channel=stdout iteration=7 job.command="cf --version" job.position=0 job.schedule="*/1 * * * *" 
   2018-03-05T10:59:00.05+0100 [APP/PROC/WEB/0] OUT time="2018-03-05T09:59:00Z" level=info msg="job succeeded" iteration=7 job.command="cf --version" job.position=0 job.schedule="*/1 * * * *"

Running Sceduled Tasks on Cloud Foundry

While the cron container here is designed to be small and lightweight, you may want to use it to trigger more resource intensive tasks and processes. When a simple curl to an http endpoint is not enough to kick off such a task on your existing app, Cloud Foundry Tasks are a great solution to run these processes.

This sample repository thus includes instructions to install the cf cli tool which you can use to trigger such a task using a Meshcloud Service User.