Python Rules for Bazel

rules_python is the home of the core Python rules – py_library, py_binary, py_test, py_proto_library, and related symbols that provide the basis for Python support in Bazel. It also contains package installation rules for integrating with PyPI and other indices.

Documentation for rules_python lives here and in the Bazel Build Encyclopedia.

Examples are in the examples directory.

Currently, the core rules build into the Bazel binary, and the symbols in this repository are simple aliases. However, we are migrating the rules to Starlark and removing them from the Bazel binary. Therefore, the future-proof way to depend on Python rules is via this repository. See Migrating from the bundled rules below.

The core rules are stable. Their implementation in Bazel is subject to Bazel’s backward compatibility policy. Once migrated to rules_python, they may evolve at a different rate, but this repository will still follow semantic versioning.

The Bazel community maintains this repository. Neither Google nor the Bazel team provides support for the code. However, this repository is part of the test suite used to vet new Bazel releases. See How to contribute for information on our development workflow.

Bzlmod support

  • Status: Beta

  • Full Feature Parity: No

See Bzlmod support for more details

Migrating from the bundled rules

The core rules are currently available in Bazel as built-in symbols, but this form is deprecated. Instead, you should depend on rules_python in your WORKSPACE file and load the Python rules from @rules_python//python:defs.bzl.

A buildifier fix is available to automatically migrate BUILD and .bzl files to add the appropriate load() statements and rewrite uses of native.py_*.

# Also consider using the -r flag to modify an entire workspace.
buildifier --lint=fix --warnings=native-py <files>

Currently, the WORKSPACE file needs to be updated manually as per Getting started.

Note that Starlark-defined bundled symbols underneath @bazel_tools//tools/python are also deprecated. These are not yet rewritten by buildifier.