> What if your cronjob doesn't fire? What if LEs script has a bug and you're not up to date? What if one of the (Python?) dependencies has a bug or breaks? What if LEs servers are being DDoS'd? Can you enumerate and account for all the failure scenarios?

I run my cron job[1] every hour. It checks for the expiry of my existing set of certificates and has a configurable parameter as to how soon before expiry to renew them.

[1] https://github.com/frutiger/concorde