GitHub Actions: Lint Python code with ruff

[cclauss]

https://github.com/astral-sh/ruff

Why ruff?

• GitHub Actions: Lint Python code with ruff mavlink/mavlink#2303 (comment)

If ruff is a superset of flake8, why doesn't it complain about the rules in this repo's .flake8 file?

ardupilot_wiki/.flake8

Lines 1 to 16 in 703219c

	[flake8]
	ignore =
	# H301: one import per line
	H301,
	# H306: imports not in alphabetical order (time, os)
	H306,
	# E226: missing whitespace around arithmetic operator
	E226,
	# E261 at least two spaces before inline comment
	E261,
	# W504 line break after binary operator
	W504,
	# E203 whitespace before ':'
	E203,
	# E221 multiple spaces before operator
	E221

Most of these are whitespace errors that are better handled by a code formatter like ruff format or psf/black, so ruff check ignores them.

[peterbarker]

Query: do we need to use random isolation tools like pipx to do this stuff?

If I'm thinking right this actually increases the changes of the job failing as it installs the tool from the internet as part of running pipx here - in a CI job that's evrey time we run the job. Th jobs on the main repository fail not infrequently because of external dependencies (including failed connections to github.com resources themselves!) so I don't know if this is an appropriate way of running the tool. I'm certainly not growing fonder of restarting CI jobs that have failed with "Connection refused" to some random thing on the internet.

Installing it on the runner image would seem to be a better option.

@khancyr hard to install ruff on the image we use for testing the Wiki?

[cclauss]

GitHub Actions docs: https://docs.github.com/en/actions/how-tos/use-cases-and-examples/building-and-testing/building-and-testing-python#using-ruff-to-lint-andor-format-code

I do not see how pipx is random. It is created by the same team that creates pip. It simplifies the running of CLI tools and scripts that contain PEP 723 inline metadata headers. GitHub Actions pre-installs it because installing into a venv is the recommendation for Python projects, and because isolated venv's avoid dependency conflicts.

It really does not matter for ruff because it contains no Python code, it is a Rust executable that is installed via pip, pipx, or uvx because it is trying to install trivially in a Python world.

I see lots of failing tests on PRs here, but I have not seen any caused by GitHub Actions servers being unable to reach PyPI. Whether pip installing or pipx installing, if the GitHub Actions servers are unable to see PyPI then the job is going to fail.

[Hwurzburg]

@khancyr ping