NixOS is a linux distribution with a purely functional package manager.
These scripts build .box images that can be used by vagrant with the vagrant-nixos plugin for development, and other images suitable for production.
First install packer and virtualbox
Then:
packer build template.json
The .box image is now ready to go. Install it into Vagrant via:
vagrant box add nixos-14.02-x86_64 nixos-14.02-x86_64-virtualbox.box
Vagrant does not have a nixos guest plugin by default, so you'll need to install vagrant-nixos.
vagrant plugin install vagrant-nixos
vagrant init nixos-14.02-x86_64
vagrant up