Indeed the payments website — that we use to recover failed Stripe payments thanks to Bestunning — was unusable with a NET::ERR_CERT_DATE_INVALID exception (on Google Chrome). We had not be notified automatically, I had not been notified automatically, it goes against everything I stand for and we had to fix this.
We already use Jenkins for a lot of things at Redsmin/Bringr (and now iAdvize) and it knows how to run jobs daily to check multiple things. Why not using it to verify SSL certificates validity as well?
So create a new jenkins job, configure it to be built daily (or even hourly) and run the shell script above:
Don't forget to configure email notifications in case of unstable build and you're done! Next time something's wrong with your website or app SSL certificate you will be notified.