From cc6d8f0545958c05080ed295830cefa71212ff26 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Laure=CE=B7t?= <laurent@fainsin.bzh>
Date: Wed, 29 Nov 2023 15:35:59 +0100
Subject: [PATCH] =?UTF-8?q?=F0=9F=8E=A8=20(hydrogen/system)=20format=20nix?=
 =?UTF-8?q?=20settings=20file=20+=20enable=20experimental=20features?=
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---
 hosts/hydrogen/system/nix/default.nix | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/hosts/hydrogen/system/nix/default.nix b/hosts/hydrogen/system/nix/default.nix
index 4626f4b..9efa733 100644
--- a/hosts/hydrogen/system/nix/default.nix
+++ b/hosts/hydrogen/system/nix/default.nix
@@ -1,4 +1,4 @@
-{ ... }: {
+{ lib, pkgs, nixpkgs, ... }: {
   # optimizations
   nix.settings.auto-optimise-store = true;
 
@@ -8,4 +8,16 @@
     dates = "weekly";
     options = "--delete-older-than 30d";
   };
+
+  # experimental features
+  nix.settings.experimental-features = [ "nix-command" "flakes" ];
+
+  # pin nixpkgs registry
+  nix.registry.nixpkgs.flake = nixpkgs;
+
+  # print diff between two generations
+  system.activationScripts.nvd-report-changes = ''
+    PATH=$PATH:${lib.makeBinPath [ pkgs.nvd pkgs.nix ]}
+    nvd diff $(ls -dv /nix/var/nix/profiles/system-*-link | tail -2)
+  '';
 }