2 files changed, 61 insertions, 0 deletions
diff --git a/modules/shared/defaults/default.nix b/modules/shared/defaults/default.nix
new file mode 100644
index 0000000..f2bb28a
--- /dev/null
+++ b/modules/shared/defaults/default.nix
@@ -0,0 +1,11 @@
+{ inputs, ... }:
+let
+  inherit (inputs) self;
+in
+{
+  imports = [
+    ./nix.nix
+  ];
+
+  system.configurationRevision = self.rev or self.dirtyRev or "dirty-unknown";
+}
diff --git a/modules/shared/defaults/nix.nix b/modules/shared/defaults/nix.nix
new file mode 100644
index 0000000..e5d7607
--- /dev/null
+++ b/modules/shared/defaults/nix.nix
@@ -0,0 +1,50 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  inherit (pkgs.stdenv.hostPlatform) isLinux;
+
+  # TODO: remove this nonsense when all implementations remove repl-flake
+  hasReplFlake =
+    lib.versionOlder config.nix.package.version "2.22.0" # repl-flake was removed in nix 2.22.0
+    || lib.versionAtLeast config.nix.package.version "2.90.0"; # but not in lix yet
+
+  hasAlwaysAllowSubstitutes = lib.versionAtLeast config.nix.package.version "2.19.0";
+in
+{
+  config = lib.mkMerge [
+    {
+      nix = {
+        settings = {
+          auto-optimise-store = lib.mkDefault isLinux;
+          experimental-features = [
+            "nix-command"
+            "flakes"
+            "auto-allocate-uids"
+          ];
+
+          trusted-substituters = [ "https://getchoo.cachix.org" ];
+          trusted-public-keys = [ "getchoo.cachix.org-1:ftdbAUJVNaFonM0obRGgR5+nUmdLMM+AOvDOSx0z5tE=" ];
+        };
+
+        gc = {
+          automatic = lib.mkDefault true;
+          options = lib.mkDefault "--delete-older-than 2d";
+        };
+      };
+
+      nixpkgs.config.allowUnfree = lib.mkDefault true;
+    }
+
+    (lib.mkIf hasReplFlake {
+      nix.settings.experimental-features = [ "repl-flake" ];
+    })
+
+    (lib.mkIf hasAlwaysAllowSubstitutes {
+      nix.settings.always-allow-substitutes = true;
+    })
+  ];
+}