Use pyproject.toml instead of requirements.txt

[bolinocroustibat]

Could it use the now standard PEP 518 / PEP 621 pyproject.toml by default, and fallback to requirements.txt if not present?

AFAIK pip install pyproject.toml instead of pip install -r requirements.txt is now fully supported by pip.

(I know there is a Poetry buildpack, but since pyproject.toml is the new standard, I don't think it should be related to Poetry, neither export to old requirements.txt like the Poetry buildpack does)

[edmorley]

@bolinocroustibat Hi! I can't wait until things are more standardised around pyproject.toml, however pip doesn't yet support installing dependencies based on the contents of pyproject.toml:
https://pip.pypa.io/en/stable/search/?q=pyproject.toml

The recent changes in pip use pyproject.toml to determine what build backed (eg setuptools) to install to build packages from source (ie packages that don't yet have a wheel), per PEP518:
https://www.python.org/dev/peps/pep-0518/#rationale

There are discussions about using pyproject.toml to specify what package installer/"frontend" to use, however it's in draft status (and also doesn't replace the requirements list, only simplifies determining what tool to run):
https://discuss.python.org/t/pep-650-specifying-installer-requirements-for-python-projects/6657
https://www.python.org/dev/peps/pep-0650/

I'll close this out for now pending future PEPs and pip support (also by the time that happens, we'll have likely migrated from this classic Heroku buildpack API v2 buildpack, to the new Cloud Native Buildpacks in another repo).

[baggiponte]

Hello! So the only way to deploy apps developed with tools like pdm on heroku is still to export the dependencies to requirements.txt, am I right? Thanks!

[edmorley]

@baggiponte Hi! The suggested approaches in #1341 (comment) are still the best way to use PDM.

[baggiponte]

thank you for the reply! (Also, where can I find updates for the current status of the cloud native buildpack implementation?)

[edmorley]

The CNB is being developed here:
https://github.com/heroku/buildpacks-python