Is there a way to get notified when deploy fails/succeeds, or when application gets restarted for some reason?
As far as I know, no. Since the alert/notification system they built a while back has been removed (based on the update to the original post by Kurt):
I guess if you deploy manually in real-time, you’ll see there and then if the deploy succeeds or fails. And if using some kind of CI service, that should alert you if any step in the process fails, so you would use its notification system instead.
For application restarts Maybe … listen out for the kill signal Fly sends to the vm. And send your own alert based on that.
Cloudflare Queues (beta), in particular, might come in handy here. Cost about $1.2 / million queued items.
The folks at Cloudflare know that Queues are a tad expensive (compared to other products on the Workers platform), so there might be a pricing change before they GA.