Python2 not found while building native package

[maca]

Hi!

I am trying to set a dev environment for a legacy project (rails which in turn uses yarn).

I have this nix files:

# shell.nix
with (import <nixpkgs> { });
let
  gems = bundlerEnv {
    name = "BeMate";
    inherit ruby;
    gemdir = ./.;
  };

  nodeDeps = (pkgs.callPackage ./default.nix { }).nodeDependencies;
in
stdenv.mkDerivation {
  name = "bemate";
  buildInputs = [ gems ruby zsh nodejs python2 ];
  buildPhase = ''
    ln -s ${nodeDeps}/lib/node_modules ./node_modules
    export PATH="${nodeDeps}/bin:$PATH"
  '';
}

# default.nix
# This file has been generated by node2nix 1.11.1. Do not edit!

{ pkgs ? import <nixpkgs> {
    inherit system;
  }
, system ? builtins.currentSystem
, nodejs ? pkgs."nodejs_14"
}:

let
  nodeEnv = import ./node-env.nix {
    inherit (pkgs) stdenv lib python2 runCommand writeTextFile writeShellScript;
    inherit pkgs nodejs;
    libtool = if pkgs.stdenv.isDarwin then pkgs.darwin.cctools else null;
  };
in
import ./node-packages.nix {
  inherit (pkgs) fetchurl nix-gitignore stdenv lib fetchgit;
  inherit nodeEnv;
}

when I do nix-shell to jump into my dev environment I get this build error.

npm ERR! gyp verb clean removing "build" directory
npm ERR! gyp verb command configure []
npm ERR! gyp verb check python checking for Python executable "python2" in the PATH
npm ERR! gyp verb `which` failed Error: not found: python2
npm ERR! gyp verb `which` failed     at getNotFoundError (/nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/which/which.js:13:12)
npm ERR! gyp verb `which` failed     at F (/nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/which/which.js:68:19)
npm ERR! gyp verb `which` failed     at E (/nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/which/which.js:80:29)
npm ERR! gyp verb `which` failed     at /nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/which/which.js:89:16
npm ERR! gyp verb `which` failed     at /nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/isexe/index.js:42:5
npm ERR! gyp verb `which` failed     at /nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/isexe/mode.js:8:5
npm ERR! gyp verb `which` failed     at FSReqCallback.oncomplete (node:fs:207:21)
npm ERR! gyp verb `which` failed  python2 Error: not found: python2
npm ERR! gyp verb `which` failed     at getNotFoundError (/nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/which/which.js:13:12)
npm ERR! gyp verb `which` failed     at F (/nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/which/which.js:68:19)
npm ERR! gyp verb `which` failed     at E (/nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/which/which.js:80:29)
npm ERR! gyp verb `which` failed     at /nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/which/which.js:89:16
npm ERR! gyp verb `which` failed     at /nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/isexe/index.js:42:5
npm ERR! gyp verb `which` failed     at /nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/isexe/mode.js:8:5
npm ERR! gyp verb `which` failed     at FSReqCallback.oncomplete (node:fs:207:21) {
npm ERR! gyp verb `which` failed   code: 'ENOENT'
npm ERR! gyp verb `which` failed }
npm ERR! gyp verb check python checking for Python executable "python" in the PATH
npm ERR! gyp verb `which` failed Error: not found: python
npm ERR! gyp verb `which` failed     at getNotFoundError (/nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/which/which.js:13:12)
npm ERR! gyp verb `which` failed     at F (/nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/which/which.js:68:19)
npm ERR! gyp verb `which` failed     at E (/nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/which/which.js:80:29)
npm ERR! gyp verb `which` failed     at /nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/which/which.js:89:16
npm ERR! gyp verb `which` failed     at /nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/isexe/index.js:42:5
npm ERR! gyp verb `which` failed     at /nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/isexe/mode.js:8:5
npm ERR! gyp verb `which` failed     at FSReqCallback.oncomplete (node:fs:207:21)
npm ERR! gyp verb `which` failed  python Error: not found: python
npm ERR! gyp verb `which` failed     at getNotFoundError (/nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/which/which.js:13:12)
npm ERR! gyp verb `which` failed     at F (/nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/which/which.js:68:19)
npm ERR! gyp verb `which` failed     at E (/nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/which/which.js:80:29)
npm ERR! gyp verb `which` failed     at /nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/which/which.js:89:16
npm ERR! gyp verb `which` failed     at /nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/isexe/index.js:42:5
npm ERR! gyp verb `which` failed     at /nix/store/kd72xr0pvi7wfssb38134my3knzzwvy1-node-dependencies-bemates-0.1.0/bemates/node_modules/isexe/mode.js:8:5
npm ERR! gyp verb `which` failed     at FSReqCallback.oncomplete (node:fs:207:21) {
npm ERR! gyp verb `which` failed   code: 'ENOENT'
npm ERR! gyp verb `which` failed }
npm ERR! gyp ERR! configure error
npm ERR! gyp ERR! stack Error: Can't find Python executable "python", you can set the PYTHON env variable.

Somehow I had python3 in my nix store but I manually removed it, before removing the error was a syntax error and not a command not found meaning gyp was attempting to use python3.
This is confusing to me, first because I don't know how python3 ended in my store, and secondly because it means the build is not pure.
I am on a m1 Darwin machine.

excuse if I use the wrong terminology, I haven't used nix for long. I am not sure how to perform the build without running nix-shell.