outputs = { self, nixpkgs, poetry2nix }:
    let
      name = "foo";
      system = "x86_64-linux";

      pkgs = import nixpkgs {
        inherit system;
        overlays = [ poetry2nix.overlay ];
      };

      poetryAttrs = {
        projectDir = ./.;
        python = pkgs.python39;

        checkPhase = ''
          py.test tests/
        '';

        overrides = pkgs.poetry2nix.overrides.withDefaults (final: prev: {
          lmdb = prev.lmdb.overrideAttrs
            (
              old: {
                # we need to patch the hard-coded path to patch,
                # see https://github.com/jnwatson/py-lmdb/blob/80d7ce6fd5531a2b2f586d9ec871fe60126f8aba/setup.py#L117
                patchPhase = ''
                  substituteInPlace ./setup.py --replace /usr/bin/patch ${pkgs.patch}/bin/patch
                '';
              }
            );
        });
      };
    in
    {
      packages.${system} = {
        ${name} = pkgs.poetry2nix.mkPoetryApplication poetryAttrs;
      };

      devShell.${system} =
        (pkgs.poetry2nix.mkPoetryEnv poetryAttrs).env;

    };
...
}

In reply to @octavioduarte:matrix.org
Off course! I didn't want to send the files without being asked to but if anybody can help that would be amazing.

I finally got time to look into your issue.

TLDR; your project builds fine with latest version of poetry2nix.

Long answer: many errors comes from outside, from python ecosystem, you can read short explanation in document. Latest version of poetry2nix contain myriad of overrides for many packages which allow to successfully build you project. I do not know why nixpkgs does not update potry2nix. But you can check amount of overrides in this files https://github.com/nix-community/poetry2nix/tree/master/overrides .

To build your project i used flake with overlay over nixpkgs. I'm not experienced user of nix, but i believe you can use flake for poetry2nix with classic nix definitions.

Here is flake.nix i used

{
  description = "test";

  inputs.flake-utils.url = "github:numtide/flake-utils";
  inputs.nixpkgs.url = "github:NixOS/nixpkgs";
  inputs.poetry2nix.url = "github:nix-community/poetry2nix";

  outputs = { self, nixpkgs, flake-utils, poetry2nix }:
    {
      # Nixpkgs overlay providing the application
      overlay = nixpkgs.lib.composeManyExtensions [
        poetry2nix.overlay
        (final: prev: {
          # The application
          example = prev.poetry2nix.mkPoetryApplication {
            projectDir = ./.;
          };
        })
      ];
    } // (flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = import nixpkgs {
          inherit system;
          overlays = [ self.overlay ];
        };
      in
      rec {

        defaultPackage = pkgs.example;
      }));
}

In reply to @jyamad:cofree.coffee
I am trying to use poetry2nix via flakes, but I need to downgrade poetry due to https://github.com/python-poetry/poetry/issues/4523 . Does anyone have an example of a flake that overrides the poetry version that poetry2nix uses?

I have a Poetry flake I can get to reliably build a Nix derivation. I've been banging my head the last two days trying to build a container image from it with dockerTools.streamLayeredImage. The data.json file I use as my "database" can't be found by the Python processing script but only inside the container. Here's the error:

$ docker run docker run -p 5000:5000 --rm -it localhost/lbob:6xwsg8ixlbpaisq1xc7ipvs5qxcs3d1m
 * Serving Flask app 'little_bits_of_buddha.app' (lazy loading)
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
 * Running on all addresses.
   WARNING: This is a development server. Do not use it in a production deployment.
 * Running on http://10.0.2.100:5000/ (Press CTRL+C to quit)
[2022-02-16 17:33:30,415] ERROR in app: Exception on / [GET]
Traceback (most recent call last):
  File "/nix/store/wmaqg26cza9vvck1wglp3xywsqabnp7n-python3.9-flask-2.0.2/lib/python3.9/site-packages/flask/app.py", line 2073, in wsgi_app
    response = self.full_dispatch_request()
  File "/nix/store/wmaqg26cza9vvck1wglp3xywsqabnp7n-python3.9-flask-2.0.2/lib/python3.9/site-packages/flask/app.py", line 1518, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/nix/store/wmaqg26cza9vvck1wglp3xywsqabnp7n-python3.9-flask-2.0.2/lib/python3.9/site-packages/flask/app.py", line 1516, in full_dispatch_request
    rv = self.dispatch_request()
  File "/nix/store/wmaqg26cza9vvck1wglp3xywsqabnp7n-python3.9-flask-2.0.2/lib/python3.9/site-packages/flask/app.py", line 1502, in dispatch_request
    return self.ensure_sync(self.view_functions[rule.endpoint])(**req.view_args)
  File "/nix/store/yr8hjra5czylkiz1pkcsclbbc7pqbyh2-python3.9-little-bits-of-buddha-0.1.0/lib/python3.9/site-packages/little_bits_of_buddha/app.py", line 10, in random_sutta
    return _random_sutta()
  File "/nix/store/yr8hjra5czylkiz1pkcsclbbc7pqbyh2-python3.9-little-bits-of-buddha-0.1.0/lib/python3.9/site-packages/little_bits_of_buddha/data.py", line 8, in _random_sutta
    with open("../data.json") as json_file:
FileNotFoundError: [Errno 2] No such file or directory: './data.json'

But the file is there:

ls /nix/store/yr8hjra5czylkiz1pkcsclbbc7pqbyh2-python3.9-little-bits-of-buddha-0.1.0/lib/python3.9/site-packages/little_bits_of_buddha/
__pycache__  app.py  data.json  data.py  run.py

Am I doing something wrong?

In reply to @k900:0upti.me
You need to actually declare that the file should be installed

This is what I thought! But poetry run lbob actually wants the source directory path. Here's what I wrote in this commit explaining the choice:

Poetry has odd behavior around relative file paths. Python scripts must
import starting from the project (`little_bits_of_buddha`) even if they
occupy the same directory. This commit fixes file paths to operate from
"project in".