Ask HN: Timer as a service

For example, every monday, I need an http request to hit my server. At that time, then some business logic would kick off.

I currently do it with polling, but I think it would make more sense as a push request. And I think it would be even better if an external server issued the request at a given interval.

I have been googling around, but haven't found any services like that. Does anyone know of anything out there?