Migrate from pep517 to using build in tests and workflows

[matthewfeickert]

Description

Given pypa/pyproject-hooks#83 it seems that pep517 is deprecated and we should switch to using build. There is documentation for build and a new Issue that tracks things pypa/pyproject-hooks#91, but in short we should be using

python -m pip install build
python -m build --sdist --wheel --outdir dist/ .

From the build docs section on "Difference from other tools":

python -m pep517.build

python-build implements a CLI tailored to end users.

pep517.build contained a proof-of-concept of a PEP 517 frontend. It "implement[ed] essentially the simplest possible frontend tool, to exercise and illustrate how the core functionality can be used". It has since been deprecated and is scheduled for removal.

Thanks to @pganssle for the alerting Tweet.

cc @alexander-held @henryiii @gordonwatts

[matthewfeickert]

It seems that there is no equivalent yet in build for pep517.check

To test the build backend for a project, run in a system shell:

python3 -m pep517.check path/to/source  # source dir containing pyproject.toml

which is used by pyhf for publishing:

pyhf/.github/workflows/publish-package.yml

Lines 32 to 34 in cab1d8d

	- name: Test the build backend is compliant with PEP517
	run: |
	python -m pep517.check .

I'll need to read more through the discussion and issues that exist to see if it exists, but I'll also be a bit annoying and tag @webknjaz now (:wave: hello again! Feel free to ignore this) as he seems to be highly in the know.

[pganssle]

To be clear, this sudden pep517.build deprecation is very unfortunate to my mind, not least of which because python-build is in pretty early alpha and has a few major show-stopping bugs like this one. pep517.build is not perfect either, mind you, but I think right now for my projects I'm at something close to a toss-up between "pin pep517" and "switch to build". Especially since the console script name might have to change (and it would be hard to implement a long deprecation period for that).

With regards to this:

It seems that there is now equivalent yet in build for pep517.check

It's not 100% clear to me that this is necessary. As far as I can tell pep517.check just does the checks that the project does before doing a build anyway, so if you're doing a build anyway, you aren't losing anything (it's just that the failure will show up in the build step, rather than in the "check the build" step).

[matthewfeickert]

As far as I can tell pep517.check just does the checks that the project does before doing a build anyway, so if you're doing a build anyway, you aren't losing anything

Yeah, I think you're right. I was just looking at the logs for this PR and the following screeenshot is showing the relevant section from

pyhf/.github/workflows/publish-package.yml

Lines 32 to 37 in cab1d8d

	- name: Test the build backend is compliant with PEP517
	run: |
	python -m pep517.check .
	- name: Build a wheel and a sdist
	run: |
	python -m pep517.build --source --binary --out-dir dist/ .

with

python -m build --sdist --wheel --outdir dist/ .

instead of pep517.build.

It seems that the same checks run in pep517.check are run in pep517.build and build and so there might not be an actual need for a check API.