These instructions were tested on a pi 3 with the latest version of raspbian (Raspbian GNU/Linux 9.8 (stretch)).
This guide assumes basic competency with the command line. It also assumes you have a functional puppet master set up with the hostname of puppet. If you can ping puppet, you should be all set. Also note that I am just getting into puppet and am not a master of this domain. There may be errors, and there is probably a better way to do this, but in my searching, I was unable to locate a good set of instructions to get this working, so here we are. Feel free to contact me for corrections.
You can either switch to root sudo -i, or prepend all the following commands with sudo.
apt update