Hi, I am trying to build packages for 3rd-party repos that use setup.py. But, they have build-time dependencies. I could package them using manually created

pyproject.toml

like:

[build-system]
requires = ["setuptools", "wheel", "torch==2.5.1+cu121"]
build-backend = "setuptools.build_meta"

defining them as

resource

and adding as a dependency to

python_distribution

. Now, I would like to generate this

pyproject.toml

using a custom target that takes the build-time dependencies as an argument, and use this generated resource as dependency to

python_distribution

. For example, using a

BUILD

like this:

pyproject_build_config(
    name = "pyproject",
    build_requirements = [
        "setuptools",
        "wheel",
        "torch==2.5.1+cu121",
    ],
)

python_distribution(
    name = "pytorch3d",
    dependencies = [
        ":pytorch3d-source",
        ":pyproject",
    ],
    generate_setup = False,
    provides = python_artifact(),
    sdist = False,
)

However, I am unsure how to get the plugin correctly. This is what I have so far, but this doesn't seem work (although there's no error either):

# register.py
from pants.core.target_types import ResourceSourceField, ResourceTarget
from pants.engine.fs import CreateDigest, Digest, FileContent
from pants.engine.rules import Get, rule
from pants.engine.target import (
    COMMON_TARGET_FIELDS,
    GeneratedSources,
    GenerateSourcesRequest,
    StringSequenceField,
)


class PyprojectBuildConfigRequirements(StringSequenceField):
    alias = "build_requirements"
    help = "List of requirements to build the package"


class PyprojectBuildConfigTarget(ResourceTarget):
    alias = "pyproject_build_config"
    core_fields = (*COMMON_TARGET_FIELDS, PyprojectBuildConfigRequirements)
    help = "Generate PEP-517/518 compliant pyproject.toml for setup.py-based builds"


class GeneratePyprojectBuildConfigRequest(GenerateSourcesRequest):
    input = PyprojectBuildConfigTarget  # This is the resource target type that we handle.


@rule
async def generate_pyproject_build_config(target: PyprojectBuildConfigRequirements) -> GeneratedSources:
    # Dynamically create content for the resource.
    build_requirements = target[PyprojectBuildConfigRequirements].value
    dependencies_list = ",".join((f'"{b}"' for b in build_requirements))
    content = f"""
[build-system]
requires = [{dependencies_list}]
build-backend = "setuptools.build_meta"
"""
    file_name = "pyproject.toml"

    # Create the file as a digest.
    digest = await Get(Digest, CreateDigest([FileContent(file_name, content.encode())]))

    # Return the generated sources.
    return GeneratedSources(digest)


def target_types():
    return [PyprojectBuildConfigTarget]


def rules():
    return [generate_pyproject_build_config]

What should I do?

Sorry for the trouble! A few extra questions: 1. When you say "doesn't work" can you be any more specific? For instance: what goal(s) are you running? What are you expecting to see? What are you seeing instead? 2. Can you share your

pants.toml

too?

I am running

pants package :pytorch3d

, but the build fails because it can't find

torch

during import, which is imported by

setup.py

in

:pytorch3d-source

. If I manually create

pyproject.toml

and add it as a

resource

, then

torch

is available for import and the package builds.

Sorry, I'm pretty unfamiliar with this part of Pants, so I don't know what's best. A macro/function/loop to templatise what you need might indeed be good enough?