Given this file structure, how can I read the contents of the setup.cfg file in a plugin, given that I have the

request.target.address

of the BUILD file? I've tried using

await Get(DigestContents, ...)

targeting a PathGlob to that file path, but it causes infinite errors complaining about the file system changing 🤔

Offhand it sounds like that should work. I've seen that infinite filesystem changing loop, and we figured out the cause but of course now I can't remember what it was. @hundreds-father-404 you probably remember?

Hello! Hm, what are the errors? Indeed it should be await Get(DigestContents, PathGlobs(["path/to/f.py"]) inside an async @rule

This doesn't work:

from pants.backend.python.goals.setup_py import SetupKwargs, SetupKwargsRequest
from pants.engine.fs import DigestContents, GlobMatchErrorBehavior, PathGlobs
from pants.engine.rules import Get, collect_rules, rule
from pants.engine.target import Target
from pants.engine.unions import UnionRule


class DeclarativeSetupKwargsRequest(SetupKwargsRequest):
    @classmethod
    def is_applicable(cls, _: Target) -> bool:
        return True


def rules():
    return [
        *collect_rules(),
        UnionRule(SetupKwargsRequest, DeclarativeSetupKwargsRequest),
    ]


@rule
async def setup_kwargs_plugin(request: DeclarativeSetupKwargsRequest) -> SetupKwargs:
    digest_contents = await Get(
        DigestContents,
        PathGlobs(
            [f"{request.target.address.spec_path}/setup.cfg"],
            description_of_origin="python declarative setup plugin",
            glob_match_error_behavior=GlobMatchErrorBehavior,
        ),
    )
    declarative_setup_contents = digest_contents[0].content.decode()
    print(declarative_setup_contents)
    return SetupKwargs({**request.explicit_kwargs}, address=request.target.address)

Ah ha.

GlobMatchErrorBehavior

should be

GlobMatchErrorBehavior.error

. Sorry that's an atrocious error message, that's from the Rust FFI boundary

🤦 Ooof. Sorry about that, missed a tiny bit of the example in the docs, but yep, that's exactly it - works perfectly now. Thanks 😄

No need to apologize - the error should have been more helpful. I'll open an issue