PR Checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature (please, look at the "Scope of the project" section in the README.md file)
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the current behavior?

Issue Number: N/A

Build artifacts by bazel build with the --build_python_zip option are unnecessary big. The size of the artifacts is at least 90MB (e.g., a zipped python binary which just prints "hello, world"). This is not great when build artifacts are included to docker images. The cause of this size issue is that the hermetic Python toolchain include the static libraries of the Python toolchain and tests for the standard libraries even though majority of users of rules_python don't need them. These files occupy 47MB (52% of an artifact of size 90MB).

Repro steps

WORKSPACE:

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

http_archive(
    name = "rules_python",
    sha256 = "a3a6e99f497be089f81ec082882e40246bfd435f52f4e82f37e89449b04573f6",
    strip_prefix = "rules_python-0.10.2",
    url = "https://github.com/bazelbuild/rules_python/archive/refs/tags/0.10.2.tar.gz",
)

load("@rules_python//python:repositories.bzl", "python_register_toolchains")

python_register_toolchains(
    name = "python3_10",
    python_version = "3.10.4",
)

BUILD:

load("@rules_python//python:defs.bzl", "py_binary")

py_binary(
    name = "hello",
    srcs = ["hello.py"],
)

hello.py:

print("hello, world!")

$ bazel build --build_python_zip //:hello
$ ls -lh bazel-bin/hello.zip
-r-xr-xr-x 1 t docker 91M Jul 17 11:55 bazel-bin/hello.zip

You can see some static libraries are included in the zip file (we have duplicated libpython3.10.a. The file size (uncompressed) of the static library is 38MB):

$ unzip -l bazel-bin/hello.zip | sort -n | grep ".a$"
     2356  2010-01-01 00:00   runfiles/python3_10_x86_64-unknown-linux-gnu/lib/itcl4.2.2/libitclstub4.2.2.a
   149348  2010-01-01 00:00   runfiles/python3_10_x86_64-unknown-linux-gnu/lib/thread2.8.7/libthread2.8.7.a
   496010  2010-01-01 00:00   runfiles/python3_10_x86_64-unknown-linux-gnu/lib/itcl4.2.2/libitcl4.2.2.a
   526406  2010-01-01 00:00   runfiles/python3_10_x86_64-unknown-linux-gnu/lib/Tix8.4.3/libTix8.4.3.a
 39633662  2010-01-01 00:00   runfiles/python3_10_x86_64-unknown-linux-gnu/lib/libpython3.10.a
 39633662  2010-01-01 00:00   runfiles/python3_10_x86_64-unknown-linux-gnu/lib/python3.10/config-3.10-x86_64-linux-gnu/libpython3.10.a

What is the new behavior?

The static libraries and tests for the standard libraries in the Python toolchain are excluded from Python runfiles built by Python rules. Build artifacts by bazel build with the --build_python_zip get smaller. The size of the artifacts is at least 43MB, saving 47MB.

Does this PR introduce a breaking change?

• Yes
• No

Other information