hosts: add nix-cache module

hosts/eris/configuration.nix

@@ -10,10 +10,9 @@
       # Include the results of the hardware scan.
       ./hardware-configuration.nix
       inputs.sops-nix.nixosModules.sops
+      ../modules/nix-cache.nix
     ];
 
-  nix.settings.experimental-features = [ "nix-command" "flakes" ];
-
   boot.loader = {
     efi = {
       canTouchEfiVariables = true;
@@ -32,10 +31,8 @@
   time.timeZone = "Asia/Shanghai";
 
   nix.settings = {
+    experimental-features = [ "nix-command" "flakes" ];
     trusted-users = [ "origami" ];
-    substituters = [
-      "https://mirrors.ustc.edu.cn/nix-channels/store"
-    ];
     auto-optimise-store = true;
   };
 

hosts/modules/nix-cache.nix

@@ -0,0 +1,27 @@
+{ inputs, lib, pkgs, ... }:
+
+{
+  nix.settings = {
+    substituters =
+      let
+        channelStore = x: "https://${x}/nix-channels/store";
+        mirrors = map (x: channelStore "mirrors.${x}.edu.cn") [
+          "bfsu"
+          "tuna.tsinghua"
+          "ustc"
+        ];
+        cachix = x: "https://${x}.cachix.org";
+      in
+      lib.flatten [
+        mirrors
+        (cachix "nix-community")
+        "https://cache.nixos.org"
+        (cachix "inclyc")
+      ];
+    trusted-public-keys = [
+      "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
+      "inclyc.cachix.org-1:izGZ+f/JLPovKX1OKd3rQZ8nPOCpvPij3+bebjxdZ2k="
+    ];
+    builders-use-substitutes = true;
+  };
+}

hosts/oparic-local-dev/configuration.nix

@@ -5,10 +5,9 @@
     [
       ./hardware-configuration.nix
       inputs.sops-nix.nixosModules.sops
+      ../modules/nix-cache.nix
     ];
 
-  nix.settings.experimental-features = [ "nix-command" "flakes" ];
-
   # BIOS + GRUB, 安装到 MBR
   boot.loader.grub = {
     enable = true;
@@ -29,10 +28,8 @@
   time.timeZone = "Asia/Shanghai";
 
   nix.settings = {
+    experimental-features = [ "nix-command" "flakes" ];
     trusted-users = [ "origami" ];
-    substituters = [
-      "https://mirrors.bfsu.edu.cn/nix-channels/store"
-    ];
     auto-optimise-store = true;
   };