NixOS: Install unfree package using different channel

Question

I am using the default nixos 17.09 channel and want to install an unfree package from the unstable channel.

I am using (import <nixos-unstable> {}).vscode to install vscode in this case, but I am getting the error that I must set ...allowUnfree = true; It seems that the setting only applies to the default channel. How can I set allowFree = true; also on the unstable channel?

Answer 1

I found a solution (https://github.com/NixOS/nixpkgs/issues/25880#issuecomment-322855573).

It creates an alias for the unstable channel with the same config.

nixpkgs.config = 
{
    # Allow proprietary packages
    allowUnfree = true;

    # Create an alias for the unstable channel
    packageOverrides = pkgs: 
    {
        unstable = import <nixos-unstable> 
            { 
                # pass the nixpkgs config to the unstable alias
                # to ensure `allowUnfree = true;` is propagated:
                config = config.nixpkgs.config; 
            };
    };
};

Then you can use it like unstable.vscode instead of (import <nixos-unstable> {}).vscode.