hi everyone I am struggling to run my custom python rule to Pants #general

hi everyone! I am struggling to run my custom pyth...

numerous-city-13071

11/17/2023, 2:39 PM

hi everyone! I am struggling to run my custom python rule (to check python classes are "simple") by running pants -> I am seeing this:

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pants.base.exceptions.BackendConfigurationError: Failed to load the gp_checks.register backend: ModuleNotFoundError("No module named 'my_checker.register'")

After adding my new rule's module to

backend_packages

inside

pants.toml

. I went through the documentation on how to define a new pylint checker and have add a

register

function:

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def register(linter: "PyLinter") -> None:
    """
    This required method auto registers the checker during initialization.

    :param linter: The linter to register the checker to.
    """
    linter.register_checker(MyChecker(linter))

MyChecker

roughly looks like:

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from pylint import checkers


class MyChecker(checkers.BaseChecker):
    ...

Now, I've seen

@rule

too, but I am unsure how to proceed -> what should I put in the

my_checker/register.py

such that my new checker can be run?

👋 1

curved-television-6568

11/17/2023, 2:47 PM

it’s all the way at the bottom of this chapter: https://www.pantsbuild.org/docs/plugins-lint-goal#3-create-a-rule-for-your-linter-logic

numerous-city-13071

11/17/2023, 2:54 PM

thanks! I actually got a bit confused here, as I have a pylint checker... but how does this become a pants rule?

MyChecker

Rule

curved-television-6568

11/17/2023, 2:56 PM

the code snippets seem to be pylint specific.. I don’t know about those…

curved-television-6568

11/17/2023, 2:59 PM

there already is a pylint backend in pants, so if you want to register a custom pylint plugin, I don’t know how that works. https://github.com/pantsbuild/pants/tree/86628a1d9c74da84992aa9b6be8a843dcdc2b808/src/python/pants/backend/python/lint/pylint

curved-television-6568

11/17/2023, 2:59 PM

i.e. it doesn’t make sense to register your pylint plugin with pants, it should be registered with pylint, somehow…

curved-television-6568

11/17/2023, 3:00 PM

for inspiration, pants does this but for mypy, here: https://github.com/pantsbuild/pants/blob/86628a1d9c74da84992aa9b6be8a843dcdc2b808/pyproject.toml#L37

curved-television-6568

11/17/2023, 3:02 PM

or perhaps more relevantly using in-repo plugin, but for flake8: https://github.com/pantsbuild/pants/blob/86628a1d9c74da84992aa9b6be8a843dcdc2b808/pants.toml#L165 just showing that it will be a tool specific configuration for it to pick up your plugin.

numerous-city-13071

11/17/2023, 3:09 PM

okay so maybe I just register the pylint plugin with pylint itself?

👆 1

numerous-city-13071

11/17/2023, 3:10 PM

how would I turn it on for only 1 module e.g. using pants config?

numerous-city-13071

11/17/2023, 3:10 PM

(thanks btw!)

curved-television-6568

11/17/2023, 3:12 PM

not sure it would be possible to selectively enable this for a single module. Perhaps you can have some conditional logic in the plugin itself if it only should apply to a specific set of modules..?

numerous-city-13071

11/17/2023, 3:12 PM

yea that's also def. possible, thanks!

👍 2

numerous-city-13071

11/20/2023, 9:24 AM

So, I have now written a working plugin for pylint... But when I want to be able to run it with pants, after generating the lock file I get this error:

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./pants lint app::

[...]

stderr:
A distribution for babel could not be resolved for /home/admin/.pyenv/versions/3.10.5/bin/python3.10.

09:20:53.41 [INFO] Canceled: Building 2 requirements for pylint.pex from the tools/python/pylint/pylint-resolve.lock resolve: astroid, pylint<3,>=2.13.0

I am unsure how to continue now... I added this to my `pants.toml`:

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[pylint]
args = [
    "--disable=all",
    "--enable=gp-check-simple-dtos",
]
config = "pyproject.toml"
lockfile = "tools/python/pylint/pylint-resolve.lock"
install_from_resolve = "pylint"
source_plugins = [
  "pylint_plugins:pylint-plugins-sources",
]
version = "pylint>=2.13.0,<2.15"

[source]
root_patterns = [
  ...
  "/pylint_plugins",
]

[python]
...
enable_resolves = true


[python.resolves.add]
...
pylint = "tools/python/pylint/pylint-resolve.lock"

backend_packages = [
   ...
  "pants.backend.python.lint.pylint",
]

And `pyproject.toml`:

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[tool.pylint]
load-plugins = [
    "check_simple_dtos",
]

This is how my

pylint_plugins/BUILD

looks like:

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python_requirement(
    requirements=["astroid", "pylint>=2.13.0,<3"],
    resolve="pylint",
)

python_sources(
    name="pylint-plugins-sources",
    sources=["**/*.py", "!**/test_*.py"],
    resolve="pylint",
)

I ran

pants generate-lockfiles --resolve=pylint

to create the lock file in

tools/python/pylint/pylint-resolve.lock

. Any help would be very welcome! Also, as a side note, I got some deprecated warnings about using

version

and

lockfile

and that I should use

install_from_resolve

instead. But, if I leave out

lockfile

then it complains that no

lockfile

is found when running the

generate-lockfiles --resolve=pylint

command.

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