Pin nixpkgs on buck

machines/buck/configuration.nix

@@ -2,7 +2,7 @@
 # your system.  Help is available in the configuration.nix(5) man page
 # and in the NixOS manual (accessible by running ‘nixos-help’).
 
-{ config, pkgs, sops, ... }:
+{ config, pkgs, inputs, sops, ... }:
 
 {
   imports =
@@ -10,6 +10,12 @@
       ./hardware-configuration.nix
     ];
 
+  # This lets us pin the nixpkgs registry by default to the nixpkgs used to build this system.
+  # Doing this means we are less likely to require the 30+MB download when
+  # running commands like nix search or nix run
+  # See: https://dataswamp.org/~solene/2022-07-20-nixos-flakes-command-sync-with-system.html
+  nix.registry.nixpkgs.flake = inputs.nixpkgs;
+
   sops = {
     # This will add secrets.yml to the nix store
     # You can avoid this by adding a string to the full path instead, i.e.