nixos/direnv: init

[Gerg-L]

Closes #192667

Description of changes

There really should be a simple direnv module and #192667 has become quite stale
So I took most of the criticisms and applied them along with a few bits of my own

I would like to make an option to conditionally load based on being in a nix shell,
but alas i couldn't get fish to work correctly

Things done

• Tested the module

[2xsaiko]

FWIW I have some extra code in my config's module for direnv to source the user's configuration also (which direnv normally does), might be worth including here. This is what configuration I install (in /etc/xdg/direnv as opposed to /etc/direnv):

    environment.etc = {
      "xdg/direnv/lib/nix-direnv.sh".source = mkIf cfg.enableNixDirenv "${pkgs.nix-direnv}/share/nix-direnv/direnvrc";

      # Also load user's config files
      "xdg/direnv/lib/zz-user.sh".text = ''
        direnv_config_dir_home="''${DIRENV_CONFIG_HOME:-''${XDG_CONFIG_HOME:-$HOME/.config}/direnv}"

        for lib in "$direnv_config_dir_home/lib/"*.sh; do
          source "$lib"
        done

        unset direnv_config_dir_home
      '';

      "xdg/direnv/direnvrc".text = ''
        direnv_config_dir_home="''${DIRENV_CONFIG_HOME:-''${XDG_CONFIG_HOME:-$HOME/.config}/direnv}"

        # load the global ~/.direnvrc if present
        if [[ -f $direnv_config_dir_home/direnvrc ]]; then
          # shellcheck disable=SC1090,SC1091
          source "$direnv_config_dir_home/direnvrc" >&2
        elif [[ -f $HOME/.direnvrc ]]; then
          # shellcheck disable=SC1090,SC1091
          source "$HOME/.direnvrc" >&2
        fi

        unset direnv_config_dir_home
      '';
    };

[Gerg-L]

FWIW I have some extra code in my config's module for direnv to source the user's configuration also (which direnv normally does), might be worth including here.

I can't see any negatives to this I'll add it

[bbenne10]

Other than one (admittedly rather nitpicky) concern re a comment: this looks like a very good approach that addresses every problem I have with #192667!

[drupol]

Now that you added a package attribute in the config, you can use it as such...

[Gerg-L]

Now that you added a package attribute in the config, you can use it as such...

Does the package gets added to automatically to systemPackages?
Probably not right?

[drupol]

Does the package gets added to automatically to systemPackages? Probably not right?

No it doesn't but your PR doesn't do it either.

[Gerg-L]

Does the package gets added to automatically to systemPackages? Probably not right?

No it doesn't but your PR doesn't do it either.

Yeah removed it with the last force push, brain fart

[drupol]

Yeah removed it with the last force push, brain fart

Then you just have to use cfg.package.

[Gerg-L]

Alright pushed changes

[Gerg-L]

I finally figured out why fish wasn't working with my conditional loading idea: direnv has a .fish file in it's $out which is automatically sourcing direnv,
I don't know whether this should be a change to the package itself it doesn't seem correct that it's automatically sourcing itself when installed --but only in fish

so I added a loadInNixShell option
It's slightly sketchy as it's just greping $PATH to detect nix shell
nix develop and nix-shell both set an env var so they're easy to detect but it should work the majority of the time and It's not active by default

I also added options to disable and set the package of nix-direnv as drupol suggested

[drupol]

A minor syntax change and I think it's good to go.

[Gerg-L]

A minor syntax change and I think it's good to go.

Changes pushed!