Cant get unfree packages to install on nixos using nix-shell

Help
1

I’m trying to install a specific version of mongodb using this command nix-shell -p mongodb-4_4 but get the below error.

error: Package ‘mongodb-4.4.13’ in /nix/store/q3w6aldk8khr1f6vd050r8ambymz43x4-nixos-22.05/nixos/pkgs/servers/nosql/mongodb/mongodb.nix:133 has an unfree license (‘SSPL’), refusing to evaluate.

       a) To temporarily allow unfree packages, you can use an environment variable
          for a single invocation of the nix tools.

            $ export NIXPKGS_ALLOW_UNFREE=1

        Note: For `nix shell`, `nix build`, `nix develop` or any other Nix 2.4+
        (Flake) command, `--impure` must be passed in order to read this
        environment variable.

       b) For `nixos-rebuild` you can set
         { nixpkgs.config.allowUnfree = true; }
       in configuration.nix to override this.

       Alternatively you can configure a predicate to allow specific packages:
         { nixpkgs.config.allowUnfreePredicate = pkg: builtins.elem (lib.getName pkg) [
             "mongodb"
           ];
         }

       c) For `nix-env`, `nix-build`, `nix-shell` or any other Nix command you can add
         { allowUnfree = true; }
       to ~/.config/nixpkgs/config.nix.
(use '--show-trace' to show detailed location information)

I have set nixpkgs.config.allowUnfree = true; in both my configuration.nix and also in my home.nix yet I still get this error.

Is there something I am missing here?

2

you need to do part C

Blockquote
c) For nix-env, nix-build, nix-shell or any other Nix command you can add
{ allowUnfree = true; }
to ~/.config/nixpkgs/config.nix

This is required even if you have it added to your configuration.nix file

3

Thanks for the reply!
This file does not exist on my system, should I create it?

4

yes

mkdir -p ~/.config/nixpkgs
echo “{ allowUnfree = true; }” >> ~/.config/nixpkgs/config.nix

5

Thanks this is working thank you so much!!!
I am surprised that I need to create a config file that is external to my configuration.nix as I thought the whole point of nixos is to have your configuration all in one place. Do you know what the reasoning is behind this?

6

honestly I’m not sure, I’m fairly new to nixos. I imagine home-manager might be able to set this up for you, but I haven’t yet gotten that far into my configuration yet.

1 Like