EugenMayer / docker-cron-boilerplate

WAT

This boilerplate will show you how to run cron or better alternatives under docker

Cron

This boilerplate should help you understand how to setup cron runs under docker, handle pseudo shells and ENV vars and avoid all the pitfalls with cron in general

a) we want to be able to run cron with other users then our docker-build user (e.g. root) b) we want to Dockerfile / docker-compose.yml ENV vars to be present for all our cron users ( see Dockerfile for the detailed info )

Jobber

Jobber is a far better alternative to cron. Far better logging, status report, syntax and general debug-ability and therefor reliability. Especially the build in tools to create random time offsets for jobs so your infra does not run something at the very same second with a huge peek, is very handy. Error handler, notifications, run histories, jobber test to see how it will run and what stdout/err looks like just makes your life a lot easier. You can also run as often as every second, not only every minute.

Downside is, the most then "echoing one line".

Why

1. we use supervisor

   Since it is in the nature that you will run cron for a specific service you also run in this docker-container most probably. So cron is just something in addition, and will most probably need you app-interpreter to be present. Maybe you run rake/thor/drush cleanup tasks or some python related cleanup jobs. Means you will have like fpm and cron and this will always require you to use supervisor - thats why we include it here out of the box, eventhough for our boilerplate, we would not need it ( since cron runs alone )

2. why the envs.sh

   See the Dockerfile for FOO=bar - it explains it pretty well

3. why printf and not echo

   Do not use echo for this