How to fix Nix build failure due to a file using the windows way to break line

I am running NixOS on WSL

I use nix version nix 2.18.1 I run

 nix develop

in the directory containing flake.nix that looks like that:

{
 description = "Python environment with ollama";

 inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
 inputs.flake-utils.url = "github:numtide/flake-utils";

 outputs = { self, nixpkgs, flake-utils, ... }:
    flake-utils.lib.eachDefaultSystem (system: let
      pkgs = nixpkgs.legacyPackages.${system};
      
      jina-hubble-sdk = with pkgs.python3Packages;
        buildPythonPackage rec {
          pname = "jina-hubble-sdk";
          version = "0.39.0";

          src = pkgs.fetchPypi {
            inherit pname version;
            sha256 = "9021417794a6d3cf3fad8a880cf668a3a986b9d53d5be5fa391aae1767a5b9b0";
          };

          nativeBuildInputs = [
            poetry-core
            pkgs.dos2unix # Add dos2unix to convert line endings
          ];

          propagatedBuildInputs = [
            pep517
            pip
            requests
            aiohttp
            rich
            importlib-metadata
            filelock
            pathspec
            docker
            pyyaml
            python-jose
          ];
          

          # Convert line endings to Unix-style
          preConfigure = ''
            export HOME=$(mktemp -d)
          '';
             # put this code inside preConfigure if you want to run it dos2unix -f /nix/store/v099hqvw5z87423p4hz1vfhzaqa07dii-stdenv-linux/setup
        };
   
      pythonEnv = pkgs:
        pkgs.python3.withPackages (ps:
          with ps; [
             jina-hubble-sdk
          ]);
    in {
      devShells.default = pkgs.mkShell {
        buildInputs = with pkgs; [
          curl
          ollama
          (pythonEnv pkgs)
        ];
      };
    });
}

and I get the following error

error: builder for '/nix/store/dm6cxw020s7whbfgqj8jivd3dv1pby0i-python3.11-jina-hubble-sdk-0.39.0.drv' failed with exit code 127; last 10 log lines: > Using setuptoolsCheckPhase > Running phase: unpackPhase > unpacking source archive /nix/store/9q6b5l6955sabgvk8ah5xx0sfji25zmn-jina-hubble-sdk-0.39.0.tar.gz > source root is jina-hubble-sdk-0.39.0 > setting SOURCE_DATE_EPOCH to timestamp 1688549032 of file jina-hubble-sdk-0.39.0/setup.cfg > Running phase: patchPhase > Running phase: updateAutotoolsGnuConfigScriptsPhase > Running phase: configurePhase > /nix/store/v099hqvw5z87423p4hz1vfhzaqa07dii-stdenv-linux/setup: line 114: $'\r': command not found > /nix/store/v099hqvw5z87423p4hz1vfhzaqa07dii-stdenv-linux/setup: line 131: pop_var_context: head of shell_variables not a function context For full logs, run 'nix-store -l /nix/store/dm6cxw020s7whbfgqj8jivd3dv1pby0i-python3.11-jina-hubble-sdk-0.39.0.drv'. error: 1 dependencies of derivation '/nix/store/25gl4f29rr56ci1h5k53wmm7wgfmk2p2-python3-3.11.8-env.drv' failed to build error: 1 dependencies of derivation '/nix/store/pxkgnl5nx66fcdi1rkvz86kbfrvlmhn2-nix-shell-env.drv' failed to build

The important line in the error message:

/nix/store/v099hqvw5z87423p4hz1vfhzaqa07dii-stdenv-linux/setup: line 114: $'\r': command not found >

I supposed that the problem is linked to the different way linux and window( see this website) have to break a line. I wanted to adapt the file that caused a problem with:

   preConfigure = ''
      #   dos2unix -f /nix/store/v099hqvw5z87423p4hz1vfhzaqa07dii-stdenv-linux/setup
      # '';

but it change nothing. Therefore I comment it but you can uncomment it to test it yourself.

Solution

Although the error message said that the problem comes from a file that is not the flake.nix that I developed, the problems comes from the flake.nix that I developed. I write the code using code opened from windows. Hence it use the dos encoding.

run nix develop in another directory containing this flake

{
 inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
 inputs.flake-utils.url = "github:numtide/flake-utils";

 outputs = { self, nixpkgs, flake-utils, ... }:
    flake-utils.lib.eachDefaultSystem (system: let
      pkgs = nixpkgs.legacyPackages.${system};
      

    in {
      devShells.default = pkgs.mkShell {
        buildInputs = with pkgs; [
            pkgs.dos2unix
        ];
      };
    });
}

You can now run

  dos2unix flake.nix

in the directory with the flake returning an error. it changed the encoding. And you can now run

 nix develop

with this flake and it will work fine

The answer comes from VTimofeenko who wrote it there : https://discourse.nixos.org/t/what-could-cause-this-flake-to-fail-on-my-computer-and-succeed-on-another/41868/2