For Rails apps I've been using god to manage unicorn and delayed_job/resque processes in recent years. I've been mildly skeptical of systemd---not really out of true knowledge but because keeping things simple matters to me, and that seems to be the gist of the criticisms. But if systemd would let me do away with god, that would be nice! I agree that pidfiles are a hack and often cause problems. It seems like I'm going to need to learn systemd soon anyway, so I'll be looking into whether it can do what I need for Rails apps.