Provide a way to publish Python packages

[calder]

Add a rule for building Python packages for distribution via PyPi. See https://github.com/horia141/bazel-pypi-package for an initial defunct attempt this.

[github-actions]

This issue has been automatically marked as stale because it has not had any activity for 180 days. It will be closed if no further activity occurs in 30 days.
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[rkhir]

Hello, is there an update on this issue? Or perhaps an alternative solution to publish Python packages?

[github-actions]

This issue has been automatically marked as stale because it has not had any activity for 180 days. It will be closed if no further activity occurs in 30 days.
Collaborators can add an assignee to keep this open indefinitely. Thanks for your contributions to rules_python!

[github-actions]

This issue was automatically closed because it went 30 days without a reply since it was labeled "Can Close?"

[alexeagle]

We now need this for rules_python itself, as we want to publish the runfiles library as a wheel to pypi.
I tried the simple thing of using twine via https://github.com/pypa/gh-action-pypi-publish but it failed our release https://github.com/bazelbuild/rules_python/actions/runs/4001340558/jobs/6867466794

In any event, I think this isn't a good solution because it's non-hermetic - you need python and twine and other stuff on the environment where you publish the wheel. I think we need a proper target that can be used with bazel run that does the publish, assuming nothing about the machine where it's run.