CODEWITHSUNDEEP
pythonnixnixpkgs
Gareth Charnock
Gareth Charnock

Reputation: 1166

In Nixpkgs, what makes a python derivation an application rather than a library?

I'm trying to package a python application for Nix, but I'm finding that the majority of the documentation assumes that I want to package a library.

In order to do this, I looked at Rednotebook example (not for any particular reason other than I happened to know it was written in python), which can be found in python-packages, but as that file is so huge, here is the relevant part:

  redNotebook = buildPythonPackage rec {
    name = "rednotebook-1.8.1";

    src = pkgs.fetchurl {
      url = "mirror://sourceforge/rednotebook/${name}.tar.gz";
      sha256 = "00b7s4xpqpxsbzjvjx9qsx5d84m9pvn383c5di1nsfh35pig0rzn";
    };

    # no tests available
    doCheck = false;

    propagatedBuildInputs = with self; [ pygtk pywebkitgtk pyyaml chardet ];

    meta = {
      homepage = http://rednotebook.sourceforge.net/index.html;
      description = "A modern journal that includes a calendar navigation, customizable templates, export functionality and word clouds";
      license = licenses.gpl2;
      maintainers = with maintainers; [ tstrobel ];
    };
  };

My derivation looks like this:

{ pkgs ? import <nixpkgs> {} }:
let
  requirements = import ./nix/requirements.nix { inherit pkgs; };
in
pkgs.python35Packages.buildPythonPackage rec {
  name = "package-name";
  version = "1.0.0";
  namePrefix = "";
  src = ./.;
  doCheck = false;
  propagatedBuildInputs = builtins.attrValues requirements.packages;
}

requirements.nix was the output of pypi2nix and requirements.packages has type "list of derivations". Despite this when I cd into the resulting store path for Rednotebook there is a /bin directory with some wrapper scripts. The store path for my app there is just a lib an no /bin

How do I tell Nixpkgs that I have an application?

Upvotes: 2

Views: 2350

Answers (3)

Ilya Gotfryd
Ilya Gotfryd

Reputation: 83

Was experimenting with building and installing a sample service written in Python. Ended up using buildPythonApplication in my installer

Important points

If you are leveraging setuptools to distribute your app you need to have the entry_points value in your setup call:

from distutils.core import setup
setup(
...
entry_points = {
  'console_scripts': ['sample_module = src.app:main']
}

src - source code folder app - entry point module name main - name of the entry point function

My whole build configuration was:

# sample.nix
with (import <nixpkgs> {});
python37.pkgs.buildPythonApplication rec {
    pname = "sample_service";
    version = "0.0.3";
    src = ./sample_package;
    meta = with lib; {
        homepage = "https://www.example.com";
        description = "Sample Python Service";
    };
}

sample_package was the folder that contained 'src' folder and 'setup.py' located at the same level as above 'sample.nix' file. At this point, if you run nix-build sample.nix it will build and install the package for you. However, to make it available on the path you will need to capture the resulting path in the nix store and run:

nix-env -i <nix_store_path>

Upvotes: 2

FRidh
FRidh

Reputation: 192

buildPythonPackage is to be used for libraries, that is, when you want it to expose its modules in site-packages. buildPythonApplication is for applications that just happen to be written in Python. In that case, when you include such a derivation in another derivation, you don't want to expose the libraries.

This separation is important because it may happen that a Python 3 environment calls a tool that is written in Python 2 and vice versa.

Note that at the time of writing this issue hasn't been completely solved yet, but at least python.buildEnv or python.withPackages will not include applications along with their dependencies.

Upvotes: 1

Emmanuel Rosa
Emmanuel Rosa

Reputation: 9895

There are buildPythonPackage and buildPythonApplication functions, but at the end of the day, they both call mkPythonDerivation.

A Python application with a simple Nix package you can reference is Ranger; which uses buildPythonApplication. The resulting derivation contains a wrapper in /nix/store/PACKAGE/bin/

Upvotes: 2

Related Questions