Action fails when setuptools.setup values are parsed from text file

[mspronesti]

I'm playing around with a dummy python package to understand how to properly use this action. This is my workflow file:

name: Upload Python Package

on:
  release:
    types: [published]

jobs:
  deploy:

    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v2
    - name: Set up Python
      uses: actions/setup-python@v2
      with:
        python-version: '3.x'
    - name: Install dependencies
      run: |
        python -m pip install --upgrade pip
        pip install build
    - name: Build package
      run: python -m build
    - name: Publish package
      uses: pypa/gh-action-pypi-publish@27b31702a0e7fc50959f5ad993c78deac1bdfc29
      with:
        user: __token__
        password: ${{ secrets.PYPI_API_TOKEN }}

It fails giving

FileNotFoundError: [Errno 2] No such file or directory: '<my_pkg_name>/VERSION.txt'
* Creating venv isolated environment...
* Installing packages in isolated environment... (setuptools >= 40.8.0, wheel)
* Getting dependencies for sdist...
* Building sdist...
* Building wheel from sdist
* Creating venv isolated environment...
* Installing packages in isolated environment... (setuptools >= 40.8.0, wheel)
* Getting dependencies for wheel...

ERROR Backend subproccess exited when trying to invoke get_requires_for_build_wheel
Error: Process completed with exit code 1.

whenever I try to do something like this:

import setuptools
import os

# loading version number from path
VERSION_PATH = os.path.join(os.path.dirname(__file__), "<my_pkg_name>", "VERSION.txt")
with open(VERSION_PATH, "r") as version_file:
    version = version_file.read().strip()

setuptools.setup(
    ...
    version=version,
    ...

If I specify the version number by hand it works as expected.
The very same error appears if I try to parse the description from the README.
Am I doing anything wrong ?

[webknjaz]

Our action does not attempt to build your project, it only uploaded the dists that you've pre-built before running it. So your question is rather out of the scope of what this project is meant to solve.

But let me give you some pointers:

1. You invoke pypa/build which is a PEP 517 compliant build front-end.
2. build reads pyproject.toml's [build-system] and based on it knows the build dependencies and the build back-end with a fallback to setuptools.
3. setuptools is what actually builds your project (it evaluates setup.py if it's present).
4. So the code in setup.py is what fails. In particular, you attempt opening a file that doesn't exist in that location.
   1. Note that when you use setuptools, it's recommended to put your static config into setup.cfg, and you can even remove setup.py.
   2. setuptools' declarative config has helpers for extracting stuff from other files dynamically. For example, long_description = file: README.rst can automatically include the README contents as long description on the distribution metadata. And there's also version = attr: <your_pkg>.__version__ that can source the version from a Python module.
   3. You could also try out a more advanced Git-based versioning plugin called setuptools-scm.
5. Note that build pre-populates an isolated build environment in a temporary directory and if you have files that are not checked into Git, they may end up not being available in that temporary environment.
6. Another thing to learn is that you can control what gets included/excluded in the source distribution. In setuptools, this is managed by a MANIFEST.in file or plugins (setuptools-scm auto-includes all the files from Git, for example).

P.S. If you have further setuptools-related questions, the best place to ask should be https://github.com/pypa/setuptools/discussions/categories/q-a

[mspronesti]

Your answer was very helpful and all the suggestions much appreciated. Thanks for being this detailed and apologies for posting in the wrong place