first building version of lpt2 as flake

common/nixpkgs.nix

@@ -0,0 +1,46 @@
+{
+  config,
+  lib,
+  ...
+}: {
+  options.my.allowUnfreePackages = lib.mkOption {
+    type = lib.types.listOf lib.types.str;
+    default = [];
+    example = ["steam"];
+  };
+  config = {
+    nixpkgs.config = {
+      # https://github.com/NixOS/nixpkgs/issues/197325#issuecomment-1579420085
+      allowUnfreePredicate = pkg: builtins.elem (lib.getName pkg) config.my.allowUnfreePackages;
+    };
+
+    nix = {
+      settings = {
+        substituters = ["https://nix-community.cachix.org" "https://cache.nixos.org/"];
+        trusted-public-keys = ["nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="];
+      };
+      gc = {
+        automatic = true;
+        dates = "daily";
+        options = "--delete-older-than 7d";
+      };
+    };
+
+    system = {
+      stateVersion = "22.11";
+      # enable auto updates
+      autoUpgrade = {
+        enable = true;
+        dates = "weekly";
+      };
+    };
+
+    documentation = {
+      enable = true; # documentation of packages
+      nixos.enable = false; # nixos documentation
+      man.enable = true; # manual pages and the man command
+      info.enable = false; # info pages and the info command
+      doc.enable = false; # documentation distributed in packages' /share/doc
+    };
+  };
+}