nix: use new nix.settings syntax

modules/core/networking.nix

@@ -1,10 +1,12 @@
-{ config, pkgs, lib, ... }:
-
-with lib;
-
-let cfg = config.pub-solar.core;
-in
 {
+  config,
+  pkgs,
+  lib,
+  ...
+}:
+with lib; let
+  cfg = config.pub-solar.core;
+in {
   options.pub-solar.core = {
     enableCaddy = mkOption {
       type = types.bool;
@@ -39,12 +41,13 @@ in
     networking.firewall.enable = true;
 
     # Customized binary caches list (with fallback to official binary cache)
-    nix.binaryCaches = cfg.binaryCaches;
-    nix.binaryCachePublicKeys = cfg.publicKeys;
+    nix.settings.substituters = cfg.binaryCaches;
+    nix.settings.trusted-public-keys = cfg.publicKeys;
 
     # These entries get added to /etc/hosts
     networking.hosts = {
-      "127.0.0.1" = [ ]
+      "127.0.0.1" =
+        []
         ++ lib.optionals cfg.enableCaddy ["caddy.local"]
         ++ lib.optionals config.pub-solar.printing.enable ["cups.local"]
         ++ lib.optionals cfg.enableHelp ["help.local"];

modules/core/nix.nix

@@ -1,19 +1,25 @@
-{ config, pkgs, lib, inputs, ... }:
-
 {
+  config,
+  pkgs,
+  lib,
+  inputs,
+  ...
+}: {
   nix = {
     # Use default version alias for nix package
     package = pkgs.nix;
-    # Improve nix store disk usage
-    autoOptimiseStore = true;
     gc.automatic = true;
     optimise.automatic = true;
+    settings = {
+      # Improve nix store disk usage
+      auto-optimise-store = true;
       # Prevents impurities in builds
-    useSandbox = true;
+      sandbox = true;
       # give root and @wheel special privileges with nix
-    trustedUsers = [ "root" "@wheel" ];
+      trusted-users = ["root" "@wheel"];
       # This is just a representation of the nix default
-    systemFeatures = [ "nixos-test" "benchmark" "big-parallel" "kvm" ];
+      system-features = ["nixos-test" "benchmark" "big-parallel" "kvm"];
+    };
     # Generally useful nix option defaults
     extraOptions = ''
       min-free = 536870912

profiles/cachix/default.nix

@@ -1,11 +1,13 @@
-{ pkgs, lib, ... }:
-let
+{
+  pkgs,
+  lib,
+  ...
+}: let
   folder = ./.;
   toImport = name: value: folder + ("/" + name);
   filterCaches = key: value: value == "regular" && lib.hasSuffix ".nix" key && key != "default.nix";
   imports = lib.mapAttrsToList toImport (lib.filterAttrs filterCaches (builtins.readDir folder));
-in
-{
+in {
   inherit imports;
-  nix.binaryCaches = [ "https://cache.nixos.org/" ];
+  nix.settings.substituters = ["https://cache.nixos.org/"];
 }

profiles/cachix/nix-community.nix

@@ -1,9 +1,9 @@
 {
-  nix = {
-    binaryCaches = [
+  nix.settings = {
+    substituters = [
       "https://nix-community.cachix.org"
     ];
-    binaryCachePublicKeys = [
+    trusted-public-keys = [
       "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
     ];
   };

profiles/cachix/nrdxp.nix

@@ -1,9 +1,9 @@
 {
-  nix = {
-    binaryCaches = [
+  nix.settings = {
+    substituters = [
       "https://nrdxp.cachix.org"
     ];
-    binaryCachePublicKeys = [
+    trusted-public-keys = [
       "nrdxp.cachix.org-1:Fc5PSqY2Jm1TrWfm88l6cvGWwz3s93c6IOifQWnhNW4="
     ];
   };