How to pass nixpkgs.config.allowUnfree to local nixpkgs repository - nix

Question

I want to use hubstaff package from local nixpkgs repository,
let
# pass config so that packages use correct allowUnfree for example
nixpkgs-local = import /home/bjorn/projects/nixpkgs { inherit config; };
in
rec {
config.allowUnfree = true;
config.packageOverrides = old: {
# packages from local nixpkgs
inherit (nixpkgs-local) safeeyes hubstaff;
....
but its unfree package, so throws unfree package error
$ sudo nixos-rebuild dry-build
building the system configuration...
error: Package ‘hubstaff-1.3.1-ff75f26’ in /home/bjorn/projects/nixpkgs/pkgs/applications/misc/hubstaff/default.nix:60 has an unfree license (‘unfree’), refusing to evaluate.
As I understand I need to pass nixpkgs.config.allowUnfree = true, but import /home/bjorn/projects/nixpkgs { inherit config; }; above is not working
P.S.
other issue I have is that I have tried to peek what value I am passing in config.nixpkgs.allowUnfree here
{ config, pkgs, lib, ... }:
let r = {
imports = [
./hardware-configuration.nix
./hardware-configuration-override.nix
./hardware-programs.nix
/home/bjorn/projects/nixpkgs/nixos/modules/services/misc/safeeyes.nix
];
....
};
in
builtins.seq (lib.debug.showVal config.nixpkgs.allowUnfree) r
but I get infinite recursion error, maybe someone knows the way to do this?

Answer 1

To answer your second "P.S." question, here's the reason why and suggestions what to do instead.
The infinite recursion occurs because the module system needs to evaluate the 'root' of every module and some attributes like imports in order to build the term that represents the root of config.
With your call to seq you're evaluating an attribute of config at a point where config itself is still being evaluated.
Technically, you can solve this by adding your seq call to an attribute instead of around the entire module. This way, config can be evaluated without evaluating your seq call.
Probably an easier way to have a look at your configuration is to import it in nix repl
nix-repl> c = import <nixpkgs/nixos> { configuration = ./nixos/root/default.nix; /* or the file usually called configuration.nix */ }
nix-repl> c.config.nixpkgs.config.allowUnfree
true
You can use the :r command to reload all files when iterating. Nix likes to cache them because the implementation is geared toward batch execution.

Answer 2

Tnx to tilpner
I was passing wrong config
Namely,
this is config that import /home/bjorn/projects/nixpkgs was expecting
nix-repl> c = import <nixpkgs/nixos> {}
nix-repl> c.config.nixpkgs
{ config = { ... }; overlays = [ ... ]; pkgs = { ... }; system = "x86_64-linux"; }
This is what I was passing
nix-repl> c.config
{ _module = { ... }; assertions = [ ... ]; boot = { ... }; config = { ... }; containers = { ... }; dysnomia = { ... }; ec2 = { ... }; environment = { ... }; fileSystems = { ... }; fonts = { ... }; gnu = false; hardware = { ... }; i18n = { ... }; ids = { ... }; jobs = «error: The option `jobs' is used but not defined.»; kde = { ... }; krb5 = { ... }; lib = { ... }; meta = { ... }; nesting = { ... }; networking = { ... }; nix = { ... }; nixpkgs = { ... }; passthru = «error: The option `passthru' is used but not defined.»; power = { ... }; powerManagement = { ... }; programs = { ... }; security = { ... }; services = { ... }; sound = { ... }; swapDevices = [ ... ]; system = {
Its the one that passed to /etc/nixos/configuration.nix
Fix:
{ config, pkgs }:
let
# pass config so that packages use correct allowUnfree for example
unfreeConfig = config.nixpkgs.config // {
allowUnfree = true;
};
nixpkgs-local = import /home/bjorn/projects/nixpkgs { config = unfreeConfig; };
in