nix run可执行但不符合预期，nix build因缺失poetry.lock文件报错

问题场景 #

用户提供了用于创建包含Python和Streamlit虚拟环境的Nix Flake配置，执行nix run仅打开Python解释器（次要问题），执行nix build时直接报错失败。

原Flake配置代码 #

{
  description = "virtual environment with python and streamlit";
  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};
        python=pkgs.python311;
        f = ps: with ps;[
          ipython
          matplotlib
          pandas
        ];
        pip_python_packages= python.withPackages(f);

        myDevTools = [
          pip_python_packages
          pkgs.streamlit
        ];
        outputName = builtins.attrNames self.outputs self.outputs;
      in {
        devShells.default = pkgs.mkShell {
          buildInputs = myDevTools;
        };

        packages.default = pkgs.poetry2nix.mkPoetryApplication {
          projectDir = self;
        };
        apps.default = {
          program  = "${python}/bin/python";
          args = [ "main.py" ];
          src = "././";
          type = "app";
      };

      });
}

报错信息 #

error:
… while evaluating the attribute 'pkgs.buildPythonPackage'

at /nix/store/s1z7nb9n6r5n0r34fabp6yybwkbr8mjk-source/pkgs/development/interpreters/python/passthrufun.nix:87:5:

   86|     withPackages = import ./with-packages.nix { inherit buildEnv pythonPackages;};
   87|     pkgs = pythonPackages;
     |     ^
   88|     interpreter = "${self}/bin/${executable}";

… while calling the 'mapAttrs' builtin

at /nix/store/s1z7nb9n6r5n0r34fabp6yybwkbr8mjk-source/pkgs/development/interpreters/python/passthrufun.nix:31:8:

   30|           value;
   31|     in lib.mapAttrs func items;
     |        ^
   32|   in ensurePythonModules (callPackage

(stack trace truncated; use '--show-trace' to show the full trace)

error: getting status of '/nix/store/ggvg85rp5qzyr9bngsl6r0pcrkyxqa49-source/poetry.lock': No such file or directory

问题根源 #

1. nix build失败原因：配置中使用了pkgs.poetry2nix.mkPoetryApplication，这个函数要求项目目录下必须存在poetry.lock和pyproject.toml文件，但当前项目未生成这些Poetry依赖管理文件，导致Nix找不到所需文件报错。
2. nix run不符合预期原因：apps.default里的src设置为././路径无效，导致Nix无法正确定位main.py，最终直接启动Python解释器而非执行目标脚本。

修复方案 #

方案1：移除Poetry相关配置（无Poetry需求时） #

如果不需要用Poetry管理依赖，直接删除packages.default部分，同时修复apps.default的路径问题：

{
  description = "virtual environment with python and streamlit";
  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};
        python = pkgs.python311;
        f = ps: with ps; [
          ipython
          matplotlib
          pandas
        ];
        pip_python_packages = python.withPackages(f);

        myDevTools = [
          pip_python_packages
          pkgs.streamlit
        ];
      in {
        devShells.default = pkgs.mkShell {
          buildInputs = myDevTools;
        };

        apps.default = {
          program = "${python}/bin/python";
          args = [ "${self}/main.py" ]; # 直接通过self指向flake目录下的main.py
          type = "app";
        };
      });
}

方案2：添加Poetry配置文件（需要Poetry管理时） #

1. 先在项目目录初始化Poetry并生成配置文件：

   poetry init
   poetry add streamlit ipython matplotlib pandas
   

   执行后会生成pyproject.toml和poetry.lock文件。
2. 调整Flake配置，保留Poetry部分并修复应用启动逻辑：

   {
     description = "virtual environment with python and streamlit";
     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; [ streamlit ipython matplotlib pandas ];
           };
   
           packages.default = pkgs.poetry2nix.mkPoetryApplication {
             projectDir = self;
           };
           apps.default = {
             program = "${self.packages.${system}.default}/bin/你的项目命令"; # 替换为pyproject.toml中定义的命令
             type = "app";
           };
         });
   }
   

验证修复 #

• 执行nix develop进入开发Shell，检查Python、Streamlit及依赖是否正常可用。
• 执行nix run，方案1会直接执行main.py，方案2会启动Poetry定义的应用命令。
• 执行nix build，方案1会默认构建开发Shell环境，方案2会基于Poetry配置构建完整应用包。

内容的提问来源于stack exchange，提问作者Pierre-olivier Gendraud