environment with local poetry project

[rokroskar]

I'm trying to build a python environment with mach-nix where one of the packages I would like in the environment is a local poetry-based project. What's the best way to go about this? I've tried something like

{ pkgs, ... }:
let
  mach-nix = import (builtins.fetchGit {
    url = "https://github.com/DavHau/mach-nix";
    ref = "refs/tags/3.5.0";
  }) { };
  python-packages = mach-nix.mkPython {
    requirements = ''
      <requirements one per line>
    '';
    };
    packagesExtra = [ mach-nix.buildPythonPackage ./path/to/project ];
  };
in
{}

but mach-nix doesn't seem to be happy with that, yielding

...
       at /nix/store/n6hsk44fw5x8kqkff2mxyd5wd6663ai5-source/mach_nix/nix/lib.nix:229:14:

          228|         Please manually specify '${for_attr}' '';
          229|       data = extract python src error_msg;
             |              ^
          230|       result = if hasAttr attr data then data."${attr}" else throw error_msg;

       … while evaluating 'extract'

       at /nix/store/n6hsk44fw5x8kqkff2mxyd5wd6663ai5-source/mach_nix/nix/lib.nix:198:28:

          197|
          198|     extract = python: src: fail_msg:
             |                            ^
          199|     let

       … while realising the context of a path

       at /nix/store/n6hsk44fw5x8kqkff2mxyd5wd6663ai5-source/mach_nix/nix/lib.nix:205:10:

          204|     in
          205|       if pathExists file_path then fromJSON (builtins.unsafeDiscardStringContext (readFile file_path)) else throw fail_msg;
             |          ^
          206|

       … while evaluating the attribute 'src' of the derivation 'package-requirements'

       at /nix/store/5n402azp0s9vza4rziv4z5y88v2cv1mq-nixpkgs/pkgs/stdenv/generic/make-derivation.nix:205:7:

          204|     // (lib.optionalAttrs (attrs ? name || (attrs ? pname && attrs ? version)) {
          205|       name =
             |       ^
          206|         let
       cannot coerce a function to a string

       at /nix/store/n6hsk44fw5x8kqkff2mxyd5wd6663ai5-source/lib/extractor/default.nix:156:14:

          155|     stdenv.mkDerivation ( (base_derivation []) // {
          156|       inherit src;
             |              ^
          157|       name = "package-requirements";

However, if I simply include the project directly in the top-level requirementsfrom pypi and then the derivation works. Ideally I would like to install it from local source...

Hints much appreciated!