Running an AS on the public internet sounds hard, but NixOS modules, coupled with nixosTests make it very approachable. In this talk we'll walk through setting up a hobby AS from scratch: what it takes legally and technically to get your own ASN and IPv6 space and the design decisions around building a fully declarative routing infrastructure using NixOS; from generating service configs in Nix, to testing service behaviour with nixosTests before it ever reaches a live upstream. This talk will be from the viewpoint of an operator that cares about reproducibility, portability and safe rollouts of the infrastructure using NixOS.