Referencing a package from config.nix seems to imply a different stdenv

[jwiegley]

On Darwin, I've created the following config.nix file:

{ packageOverrides = pkgs: with pkgs; rec {

systemToolsEnv = pkgs.buildEnv {
    name = "systemTools";
    paths = [
      coreutils findutils gnused gnutar httrack iperf mosh mtr multitail
      p7zip parallel pdnsd gnupg pinentry pv rsync silver-searcher socat
      stow watch xz
    ];
  };

}; }

If I install that list of dependencies manually, using:

nix-env -i <paths>

Then everything installs fine. But if I install the buildEnv above with:

nix-env -iA nixpkgs.systemToolsEnv

Then it tries to pull in binutils, gcc-apple-wrapper, and different derivations for bash, coreutils, and several other packages. It seems like it's trying to build these paths using a different stdenv than what gets used by all-packages.nix.

How can I determine the "decision chain" which is leading to it trying to use binutils when installed one way, but not the other?

[jwiegley]

Conversely, how do I reference these packages from all-packages.nix in my config.nix such that it does use the correct stdenv?

[jwiegley]

It works if I define my config.nix like this:

{ pkgs }:

{ packageOverrides = self: with pkgs; rec {

systemToolsEnv = pkgs.buildEnv {
    name = "systemTools";
    paths = [
      coreutils findutils gnused gnutar httrack iperf mosh mtr multitail
      p7zip parallel pdnsd gnupg pinentry pv rsync silver-searcher socat
      stow watch xz
    ];
  };

}; }

I recommend that this be documented on the following page:

https://nixos.org/wiki/Nix_Modifying_Packages#Creating_a_config.nix_File

[peti]

The current pkgs set is an argument to the packagesOverrides function. IMHO, the most idiomatic way to write overrides is:

{
  packageOverrides = pkgs: with pkgs; {
    # do stuff here 
  };
}

[jwiegley]

Yes, but it doesn't work. See above.

[peti]

Well, it works just fine for me! What does env | grep NIX say on your system? And could you please also paste the output from ls -ld ~/.nix-defexpr && ls -la ~/.nix-defexpr?

[jwiegley]

hermes:~ $ env | grep NIX
NIX_CONF_DIR=/Users/johnw/.nix
NIX_PATH=nixpkgs=/Users/johnw/Projects/nixpkgs:/nix/var/nix/profiles/per-user/johnw/channels/nixpkgs:nixpkgs=/Users/johnw/.nix-defexpr/channels/nixpkgs
hermes:~ $ ls -ld ~/.nix-defexpr
drwxr-xr-x 3 johnw staff 102 Apr 24 00:44 /Users/johnw/.nix-defexpr
hermes:~ $ ls -ld ~/.nix-defexpr/*
lrwxr-xr-x 1 johnw staff 24 Apr 23 23:48 /Users/johnw/.nix-defexpr/nixpkgs -> /Users/johnw/src/nixpkgs

[peti]

Are /Users/johnw/Projects/nixpkgs and /Users/johnw/src/nixpkgs the same path on your system? Your NIX_PATH refers to both of them, which doesn't seem right.

[peti]

Does it make any difference if you set

export NIX_PATH=/nix/var/nix/profiles/per-user/johnw/channels/nixpkgs:nixpkgs=/Users/johnw/src/nixpkgs

before running nix-env?

[gridaphobe]

@jwiegley is this still an issue?

[peti]

I believe we found out at some point that there's a difference between pkgs.foo and pkgs.pkgs.foo in the context of packageOverrides = pkgs: { ... }. The name pkgs refers to the package set without overrides applied, and the latter refers to the package set after overrides have been applied. Thus, it's important to distinguish which package set is used to resolve references. In the Haskell package set world, we usually call these two sets self and super.

After figuring all this out, I re-wrote my ~/.nixpkgs/config.nix file to read:

{
  packageOverrides = super: let self = super.pkgs; in {
    ...
  };
}

Now, I can override a package like so:

rWrapper = super.rWrapper.override {
  packages = with self.rPackages; [ assertthat ];
};