nix-direnv cannot find nixpkgs with nix-2.4

[deejayem]

I have a .envrc containing use nix, and a shell.nix containing with import <nixpkgs> {}; stdenv.mkDerivation { name = "name"; nativeBuildInputs = [ (leiningen.override { jdk = jdk11; }) ]; }

This works fine with nix 2.3, but after upgrading to nix (Nix) 2.4pre-rc1, I get the following when I cd into the directory:
error: file 'nixpkgs' was not found in the Nix search path (add it using $NIX_PATH or -I)

However, nix-shell still works, and if I use direnv without nix-direnv, that also works.

I'm on macos, and am using home-manager (programs.direnv.nix-direnv.enable = true;), if that's relevant.

$ nix-channel --list`
home-manager https://github.com/nix-community/home-manager/archive/master.tar.gz
nixpkgs https://nixos.org/channels/nixpkgs-unstable

The full output after using cd is as follows:

direnv: loading ~/src/foo/.envrc
direnv: using nix
error: file 'nixpkgs' was not found in the Nix search path (add it using $NIX_PATH or -I)
direnv: using cached derivation
direnv: eval /Users/djm/src/foo.direnv/cache-unknown
direnv: export +IN_NIX_SHELL +TEMPDIR +XDG_DATA_DIRS ~PATH

[Mic92]

It seems that NIX_PATH is no longer set by your setup. In NixOS where I use flakes I usually solve it like this: https://github.com/Mic92/dotfiles/blob/f4711c4cd4fb717130da4e3e1a8ba6263fa20507/nixos/configurations.nix#L21

If you use channels make sure that they are included in your $NIX_PATH environment variable:

$ ls -la $HOME/.nix-defexpr/channels
nixpkgs 
$ export NIX_PATH=$HOME/.nix-defexpr/channels

Sorry but this issue is not related to nix-direnv and nix-direnv cannot magically fix your setup. So I am closing this.
I hope the instructions above are helpful.

[mkhl]

it seems that nix 2.4 is using default values when NIX_PATH is unset (NixOS/nix@ec9dd9a), and that because of this the default profile setup doesn't set NIX_PATH anymore

so the cause of this issue is that nix-direnv depends on and uses nix-2.3.16 instead of the nix it's installed with, and that version fails to deal with the setup provided by nix 2.4 (and generates warnings about newer config settings like warning: unknown setting 'experimental-features')

[Mic92]

it seems that nix 2.4 is using default values when NIX_PATH is unset (NixOS/nix@ec9dd9a), and that because of this the default profile setup doesn't set NIX_PATH anymore

so the cause of this issue is that nix-direnv depends on and uses nix-2.3.16 instead of the nix it's installed with, and that version fails to deal with the setup provided by nix 2.4 (and generates warnings about newer config settings like warning: unknown setting 'experimental-features')

We upgraded nix-direnv to point to nix-2.4 now by default quite recently: NixOS/nixpkgs#145236

[mkhl]

perfect, then i'll just wait until that gets released and hits the channel. thank you!