A simple nix-shell script to establish an environment for Phoenix, Elixir and PostgreSQL development

shell.nix

{ nixpkgs   ? import <nixpkgs> {}
, version   ? "0.1"
, proxy     ? "http://10.183.23.58:3128"
}:

with nixpkgs;

let
    elixir     = beam.packages.erlangR21.elixir_1_7;
    nodejs     = nodejs-10_x;
    postgresql = postgresql100;

    deps =
      [ elixir
        nodejs
        git
        postgresql
        glibcLocales
        fish
        neovim
        vimPlugins.spacevim
        inotify-tools
      ];

    env = buildEnv {
      name = "ex-build-environment";
      paths = deps;
    };

in

stdenv.mkDerivation rec {
  name = "ex-${version}";
  buildInputs = [ env ];
  phases = ["nobuild"];
  postPatch = "patchShebangs .";
  preConfigure = ''
    echo Running preConfigure...
    echo ${version} > VERSION
    ((git log -1 --pretty=format:"%H") || echo dirty) > GIT_COMMIT_ID
    ./boot
  '';
  HTTP_PROXY          = "${proxy}";
  HTTPS_PROXY         = "${proxy}";
  http_proxy          = "${proxy}";
  https_proxy         = "${proxy}";

  shellHook           = ''
    # "nix-shell --pure" resets LANG to POSIX, this breaks "make TAGS".
    export LANG="en_US.UTF-8"
    export PGDATA="$PWD/db"
    mix local.hex
    mix archive.install hex phx_new 1.4.0
  '';
  enableParallelBuilding = true;
  stripDebugFlags = [ "-S" ];

  # Without this, we see a whole bunch of warnings about LANG, LC_ALL and locales in general.
  # In particular, this makes many tests fail because those warnings show up in test outputs too...
  # The solution is from: https://github.com/NixOS/nix/issues/318#issuecomment-52986702
  LOCALE_ARCHIVE = if stdenv.isLinux then "${glibcLocales}/lib/locale/locale-archive" else "";

  nobuild = ''
    echo Do not run this derivation with nix-build, it can only be used with nix-shell
  '';
}

Use nix-shell --pure to enter shell with no environment leakage...

Owe you a beer/nutella/etc for the locale-archive solution! Don't know how long it took you to track it down, but it made my life easier.