bazel-contrib / bazel-contrib/rules_python

Create py_zipapp_binary to for building zip from py_binary

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Good first issue
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Starlark
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15 h 7 min
PR mergées (30 j)
76

Description

Right now, py_binary has an implicit output (`{name}.zip}`) and output group (`python_zip_file`) that builds a zip file of the py_binary. This zip file is a "zipapp", basically a zip file with a top-level `__main__.py` file. See https://peps.python.org/pep-0441/ and https://docs.python.org/3/library/zipapp.html for details.

If the Bazel builtin flag `--build_python_zip` is set, then the zip output changes slightly: it is turned into a self-executable zip file by prepending some shell code to the zip file.

Having this part of py_binary itself is problematic for four main reasons:
1. It makes maintaining py_binary harder. The logic for creating the zip is subtle and introduces several branches on code that is otherwise straight forward.
2. A zipapp is just one of many ways to create a "distributable" py_binary. It doesn't make sense to bake one directly into py_binary.
3. A zipapp only works if it's pure-python code. If there are C library dependencies, then the zip _must_ be extracted, which then breaks the logic for handling zipapp-based startup.
4. A zip file doesn't have native support for symlinks. This makes it incompatible with bootstrap=script and how it creates a venv with symlinks to the desired python interpreter. Working around this requires hacks being applied at runtime with their own problems.

What to do:

* [x] Create a `py_zipapp_binary` and `py_zipapp_test` rule. As input, they take a py_binary As output, they produce a zipapp. An attribute decides if its executable or not.
* [x] As part of the above: create a tool to generate zip files that contain symlinks. Use `File.is_symlink` to detect if inputs should be symlinks or not. For a python-based implementation, how to create a symlink: https://stackoverflow.com/questions/35782941/archiving-symlinks-with-python-zipfile . It doesn't necessairily have to be implemented in Python. Another language is fine, however, if it's a compiled language, then we'll need to update rules_python handle building and consuming prebuilt artifacts.
* [x] Add windows support to py_zipapp_binary et al
* [x] Add python_zip_file output group to py_zipapp for compatibility
* [x] Add deprecation warning for py_binary zipapp usage
* [x] Add entries to features.bzl
* [x] Default windows to non-zip builds
* [ ] Disable and remove the `--build_python_zip` flag and `python_zip_file` output group.

I'll note that there are rule sets, e.g. rules_pkg that support somewhat arbitrary creation of zip files. Using one of those would also be fine.

Guide de contribution

Ouvrir le guide de contribution

Piste de recherche

Start by locating the remaining --build_python_zip flag and python_zip_file output-group references in the repository. Review the existing py_zipapp_binary and py_zipapp_test implementation and its compatibility entries, then verify that removing the legacy interfaces leaves the documented zipapp behavior and tests intact.

Rédigé par le modèle d'indexation à partir du texte de l'issue.

Évaluation

Stack technique
python
Domaine
build-system, tooling
Type d'issue
Fonctionnalité
Difficulté
4/5
Temps estimé
3-5 jours
Activité
Calme
Clarté
Plutôt claire
Accessibilité débutants
35/100

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