Hey Fred - I do believe we met when I was chatting with edX a little while back, funny seeing you around the internet. =) And yeah, this is much more of what I would describe as "serverless". It kind of sounds like what you're doing is pretty Packer-compatible; any particular reason you guys went the way you did?
For my purposes, Packer isn't always available, which is a bummer. The Chef Zero approach I described above is nice for my purposes because it works with either an AMI or a live instance; when I write cookbooks I break them into "bake" and "configure" recipes and sub-recipes, and the "bake" steps are effectively memoization of steps I also run (idempotently) when a machine comes up.
For my purposes, Packer isn't always available, which is a bummer. The Chef Zero approach I described above is nice for my purposes because it works with either an AMI or a live instance; when I write cookbooks I break them into "bake" and "configure" recipes and sub-recipes, and the "bake" steps are effectively memoization of steps I also run (idempotently) when a machine comes up.