Challenges

• Currently 90 days, but this doesn't play well with Let's Encrypt certs
• Not currently customisable at all
• Even if this was globally customisable, it would be difficult to find a value that works for both annual & 90-day LE certs 
  • Potential solution is to allow the notification window to be set per certificate, but would prefer to avoid this

Solution

• Potentially we can allow global customisation based on the certificate lifetime (end date - start date = lifetime?):
  • If more than 90 days lifetime, alert at $config_certificate_notify_long_life
  • If less than 30 days lifetime, alert at $config_certificate_notify_short_life
  • Both vars set in Admin Settings > Notifications?