supercronic VS cron

For use inside containers, a nice Cron is Superchronic:

https://github.com/aptible/supercronic

Beware! It explicitly does not run jobs in an empty environment - it's not a great candidate for system level Cron. But for its intended usecase it is very nice.

We use https://github.com/aptible/supercronic for crons if we need to.

We will use its fat image, as it comes with Apache, Superconic, and Composer and it already has common PHP extensions enabled.

A little off topic from your post, but you should check out Supercronic - https://github.com/aptible/supercronic

Maybe instead of demons with config files that have more and more bespoke syntax, it's better to go all the way to a library that provides the basic loop functionality? Like https://github.com/c-blake/cron or something similar in C or whatever.

Maybe not, but it's an idea worth considering...

https://github.com/c-blake/cron might interest you. This uses "job" from GP in the sense of "cron jobs", although GP meant something much more broad by "jobs in C". ;-)

The key idea is portable to any prog.lang. you might like, although many will not be as run-time efficient as Nim, C, etc. and many may not be as syntax safe as Nim.