That's mostly an effect of Rails. "Convention over configuration" was one of the early mantras, and usually it serves well for such a large API...but sometimes it's just magic.
Ruby itself is a fairly explicit and consistent language. Some of the syntax might seem surprising at first if you haven't bought into the "everything is an object (really)" perspective.
Chef is pretty magical as well. I think it's easy to get carried away with syntax-sugary DSLs at the expense of of straightforwardness in Ruby if you aren't disciplined about simplicity.
Ruby itself is a fairly explicit and consistent language. Some of the syntax might seem surprising at first if you haven't bought into the "everything is an object (really)" perspective.