I don't know what life is like for Rails devs, but just getting Chef up and running is painful enough that it killed any latent interest I might have had in ever diving into Ruby.
In that case, part of the problem was documentation (as far as I can tell in retrospect, I never really needed anything other than the Ruby 1.8.7 I already had installed), but just being exposed to rbenv and the mess of that world left a bad taste in my mouth.
Of course, it's not just Ruby. I have no use for the similar tools for any environment, that purport to let you keep multiple versions installed simultaneously. Whether it's for Python, Groovy, Ruby, whatever. I've come to the conclusion that it's just plain A Bad Idea to do that sort of thing.
Ran "update-alternatives" and set Ruby back to 1.9.3 and now when I try to install the Gems, I get failures like:
"in `require': cannot load such file -- mkmf (LoadError)"
I think I'm making progress, but man, this is frustrating.
To be fair though, the basic Chef install is done and working, and I can run "knife client list" and see my clients. It's just that I'm trying to get through this EC2 tutorial and it has you installing this specific list of Gems, and that's where the problems are now. sigh
If you're not a Rubyist and just wants to use Chef, Chef's own Debian packages work great. You can ignore RubyGems and update-alternatives and other stuff, Chef's Debian packages provide everything you need.
I think that Chef should go through the tutorials and clean up the old things.