NixOS is a Linux distribution built on top of the Nix package manager, a purely functional package manager. In NixOS, a system configuration is built from a declarative specification capturing the complete system configuration. Moreover, because of the Nix heritage, a user can safely and efficiently install multiple configurations next to each other without interference. This allows users to perform atomic upgrades and rollbacks of a complete Linux distribution.In this talk we explain how we can use NixOS to manage a network of machines by using a declarative specification of a network of NixOS configurations. Less