Python shell from `buildPythonPackage`

Help
1

I’ve been working on a python package using nix-shell and a shell.nix, installing all dependencies with nix (no pip or virtualenv).

I now converted that shell.nix to a default.nix in the vein of the ones in nixpkgs (a function with dependencies as parameters, and a buildPythonPackage) because I’m thinking of using it for deployment.

But I’d like to be able to drop to a shell like before, with a python with all the dependencies set up.

How do I write a shell.nix that uses my default.nix to get to that point?

Something like this:

{ pkgs ? import ./pin.nix {} }:
with pkgs;
with pkgs.python.pkgs;
let thePackage = callPackage ./default.nix {};
in mkShell {
  propagateBuildInputs = [
    thePackage
  ];
}

builds the package OK and gives me the right python version, but with no dependencies importable.

(Oh, I’d need to have also the test dependencies, to run tests manually.)

2

This works, sort of:

{ pkgs ? import ./pin.nix {} }:
with pkgs;
with pkgs.python.pkgs;
let crawlers = callPackage ./default.nix {};
in (pkgs.python.buildEnv.override {
  extraLibs = crawlers.propagatedBuildInputs;
 }).env

but no test dependencies.

3

You should be able to do nix-shell default.nix.

probably the easiest solution would be to import your default.nix from your shell.nix. nix-shell should do the right thing

4

Once I deleted the setup.py that worked, but I still don’t have the test dependencies.

5

nix-shell default.nix -A "" may also work

6

Is there any way to access the checkInputs of a Python derivation?

7

checkInputs aren’t included in the shellHook logic:

  buildInputs = mergeInputs "buildInputs";
  nativeBuildInputs = mergeInputs "nativeBuildInputs";
  propagatedBuildInputs = mergeInputs "propagatedBuildInputs";
  propagatedNativeBuildInputs = mergeInputs "propagatedNativeBuildInputs";

  shellHook = lib.concatStringsSep "\n" (lib.catAttrs "shellHook"
    (lib.reverseList inputsFrom ++ [attrs]));

sounds like you want a python development environment. I would recommend looking at https://github.com/NixOS/nixpkgs/blob/c69153580b37c37964f2a01f113813fc0b7975a1/doc/languages-frameworks/python.section.md#how-to-consume-python-modules-using-pip-in-a-virtual-environment-like-i-am-used-to-on-other-operating-systems

8

But I don’t want to use pip…

9

shell.nix:

let
  pkgs = import <nixpkgs> {};
in pkgs.mkShell (import ./default.nix).overrideAttrs(oldAttrs: {
  buildInputs = oldAttrs.buildInputs ++ oldAttrs.checkInputs;
  })
10

Hmmm, no luck. It says checkInputs is not an attribute. I’ll try some more tomorrow, but for now, thanks :slight_smile:

11

This is a shell.nix that works for me:

{ pkgs ? import ./pinned.nix {} }:
with pkgs;
with pkgs.python.pkgs;
let
  crawlers = callPackage ./default.nix {};
  pydrv = (pkgs.python.buildEnv.override {
    extraLibs = crawlers.buildInputs ++ crawlers.nativeBuildInputs ++ [
      # Development stuff
      mypy pylama pylint black isort ipython
      # Deployment stuff
      shub
    ];
  });
in mkShell {
  buildInputs=[
    pydrv crawlers.buildInputs jre
    # Development stuff
    nodejs yarn
  ];
}

Only problem is that jre is in the checkInputs of default.nix, but needs to be mentioned again here. Can live with that