feat(rules): describe runfiles groups for rules_runfiles_group

.bazelrc

@@ -96,3 +96,7 @@ import %workspace%/specialized_configs.bazelrc
 import %workspace%/buildbuddy.bazelrc
 
 try-import user.bazelrc
+
+# TODO: Delete before merging. rules_runfiles_group's describer API isn't in the
+# BCR yet; see https://github.com/bazelbuild/rules_java/pull/368.
+common --registry=https://bazel-contrib.github.io/rules_runfiles_group --registry=https://bcr.bazel.build

MODULE.bazel

@@ -9,6 +9,7 @@ bazel_dep(name = "bazel_skylib", version = "1.8.2")
 bazel_dep(name = "package_metadata", version = "0.0.7")
 bazel_dep(name = "platforms", version = "0.0.11")
 bazel_dep(name = "rules_cc", version = "0.2.17")
+bazel_dep(name = "rules_runfiles_group", version = "99.0.0-dev.20261019.1.d105dfa")
 bazel_dep(name = "toml.bzl", version = "0.4.1")
 
 # Those are loaded only when using py_proto_library

examples/bzlmod/.bazelrc

@@ -24,3 +24,6 @@ test --test_output=errors --enable_runfiles
 # Windows requires these for multi-python support:
 build --enable_runfiles
 common:bazel7.x --incompatible_python_disallow_native_rules
+
+# TODO: Delete before merging; see the root .bazelrc.
+common --registry=https://bazel-contrib.github.io/rules_runfiles_group --registry=https://bcr.bazel.build

examples/multi_python_versions/.bazelrc

@@ -5,3 +5,6 @@ build --enable_runfiles
 
 coverage --java_runtime_version=remotejdk_11
 common:bazel7.x --incompatible_python_disallow_native_rules
+
+# TODO: Delete before merging; see the root .bazelrc.
+common --registry=https://bazel-contrib.github.io/rules_runfiles_group --registry=https://bcr.bazel.build

examples/pip_parse/.bazelrc

@@ -1,3 +1,6 @@
 # https://docs.bazel.build/versions/main/best-practices.html#using-the-bazelrc-file
 try-import %workspace%/user.bazelrc
 common --incompatible_python_disallow_native_rules
+
+# TODO: Delete before merging; see the root .bazelrc.
+common --registry=https://bazel-contrib.github.io/rules_runfiles_group --registry=https://bcr.bazel.build

gazelle/.bazelrc

@@ -27,3 +27,6 @@ build --enable_runfiles
 common --noincompatible_no_implicit_file_export
 
 common:bazel7.x --incompatible_python_disallow_native_rules
+
+# TODO: Delete before merging; see the root .bazelrc.
+common --registry=https://bazel-contrib.github.io/rules_runfiles_group --registry=https://bcr.bazel.build

gazelle/examples/bzlmod_build_file_generation/.bazelrc

@@ -14,3 +14,6 @@ common:bazel7.x --incompatible_python_disallow_native_rules
 # rules_python code. In the BCR presubmits, this override is removed
 # and the bazel_dep version of rules_python is used.
 common --override_module=rules_python=../../../
+
+# TODO: Delete before merging; see the root .bazelrc.
+common --registry=https://bazel-contrib.github.io/rules_runfiles_group --registry=https://bcr.bazel.build

internal_dev_deps.bzl

@@ -252,9 +252,9 @@ def rules_python_internal_deps():
 
     http_archive(
         name = "bazel_features",
-        sha256 = "d7787da289a7fb497352211ad200ec9f698822a9e0757a4976fd9f713ff372b3",
-        strip_prefix = "bazel_features-1.9.1",
-        url = "https://github.com/bazel-contrib/bazel_features/releases/download/v1.9.1/bazel_features-v1.9.1.tar.gz",
+        sha256 = "5450bfb2c8b4bc961c75368838f86156f563cc9adef1be7d504fc5619d54daab",
+        strip_prefix = "bazel_features-1.51.0",
+        url = "https://github.com/bazel-contrib/bazel_features/releases/download/v1.51.0/bazel_features-v1.51.0.tar.gz",
     )
 
     http_archive(

news/3757.added.md

@@ -0,0 +1,5 @@
+(rules) `py_binary` and `py_test` describe their runfiles groups for
+[rules_runfiles_group](https://github.com/bazel-contrib/rules_runfiles_group),
+so packaging rules like rules_img's `image_from_binary` can put the runtime,
+each PyPI package and each library in a layer of its own. Needs Bazel 8.8 or
+later ([#3757](https://github.com/bazel-contrib/rules_python/issues/3757)).

python/private/BUILD.bazel

@@ -20,6 +20,12 @@ load(":bazel_config_mode.bzl", "bazel_config_mode")
 load(":distribution_filegroup.bzl", "distribution_filegroup")
 load(":py_exec_tools_toolchain.bzl", "current_interpreter_executable")
 load(":py_interpreter_program.bzl", "py_interpreter_program")
+load(
+    ":runfiles_groups.bzl",
+    "py_executable_runfiles_group_describer",
+    "py_library_runfiles_group_describer",
+    "py_runtime_pair_runfiles_group_describer",
+)
 load(":sentinel_impl.bzl", "sentinel")
 load(":stamp_impl.bzl", "stamp_build_setting")
 load(":uncachable_version_file.bzl", "define_uncachable_version_file")
@@ -849,6 +855,23 @@ bzl_library(
     ],
 )
 
+bzl_library(
+    name = "runfiles_groups",
+    srcs = ["runfiles_groups.bzl"],
+    deps = [
+        ":attributes",
+        ":common",
+        ":flags",
+        ":py_executable",
+        ":py_executable_info",
+        ":py_info",
+        ":py_internal",
+        ":py_library",
+        ":reexports",
+        "@rules_runfiles_group//runfiles_group:describe",
+    ],
+)
+
 bzl_library(
     name = "runtime_env_repo",
     srcs = ["runtime_env_repo.bzl"],
@@ -1044,3 +1067,21 @@ bzl_library(
     name = "visibility",
     srcs = ["visibility.bzl"],
 )
+
+# Runfiles group describers of the Python rules (see runfiles_groups.bzl), held
+# by their _aspect_rule_hints attributes. Not actually public; only public
+# because they're implicit dependencies of rules built via the rule builders.
+py_library_runfiles_group_describer(
+    name = "py_library_runfiles_group_describer",
+    visibility = ["//visibility:public"],
+)
+
+py_executable_runfiles_group_describer(
+    name = "py_executable_runfiles_group_describer",
+    visibility = ["//visibility:public"],
+)
+
+py_runtime_pair_runfiles_group_describer(
+    name = "py_runtime_pair_runfiles_group_describer",
+    visibility = ["//visibility:public"],
+)

python/private/py_executable.bzl

@@ -93,10 +93,17 @@ EXECUTABLE_ATTRS = dicts.add(
     WINDOWS_CONSTRAINTS_ATTRS,
     # starlark flags attributes
     {
+        # Read by rules_runfiles_group's packaging aspects; see runfiles_groups.bzl.
+        "_aspect_rule_hints": attr.label_list(default = [
+            "//python/private:py_executable_runfiles_group_describer",
+            # What //python:toolchain_type is an alias of.
+            "@bazel_tools//tools/python:toolchain_type",
+        ]),
         "_build_python_zip_flag": attr.label(default = "//python/config_settings:build_python_zip"),
         "_default_to_explicit_init_py_flag": attr.label(default = "//python/config_settings:incompatible_default_to_explicit_init_py"),
         "_python_import_all_repositories_flag": attr.label(default = "//python/config_settings:experimental_python_import_all_repositories"),
         "_python_path_flag": attr.label(default = "//python/config_settings:python_path"),
+        "_runfiles_group_attrs": attr.string_list(default = ["_debugger_flag", "data", "deps", "srcs"]),
     },
     {
         "interpreter_args": lambda: attrb.StringList(

python/private/py_library.bzl

@@ -116,6 +116,11 @@ This allows optimizing the generation of symlinks to be cheaper at analysis time
         "_add_srcs_to_runfiles_flag": lambda: attrb.Label(
             default = labels.ADD_SRCS_TO_RUNFILES,
         ),
+        # Read by rules_runfiles_group's packaging aspects; see runfiles_groups.bzl.
+        "_aspect_rule_hints": lambda: attrb.LabelList(
+            default = ["//python/private:py_library_runfiles_group_describer"],
+        ),
+        "_runfiles_group_attrs": lambda: attrb.StringList(default = ["data", "deps", "srcs"]),
     },
 )
 

python/private/py_repositories.bzl

@@ -72,6 +72,12 @@ def py_repositories(transition_settings = []):
         strip_prefix = "rules_cc-0.1.5",
         urls = ["https://github.com/bazelbuild/rules_cc/releases/download/0.1.5/rules_cc-0.1.5.tar.gz"],
     )
+    http_archive(
+        name = "rules_runfiles_group",
+        sha256 = "0c5a2998f970e8ec27daa9bc10c3cd0d4a7167371acd70974a75ab8aafb41c74",
+        strip_prefix = "rules_runfiles_group-d105dfab75fb550bcfc0d2cc033b27fad0dfc2e4",
+        url = "https://bazel-contrib.github.io/rules_runfiles_group/assets/rules_runfiles_group/99.0.0-dev.20261019.1.d105dfa/source.tar.gz",
+    )
     http_archive(
         name = "toml.bzl",
         sha256 = "63633c762bdb4d836add5a9a81deeeae93c4b2edbd62ac032733020b5652b90a",

python/private/py_runtime_pair_rule.bzl

@@ -133,6 +133,11 @@ The runtime to use for Python 3 targets. Must have `python_version` set to
 `PY3`.
 """,
         ),
+        # Read by rules_runfiles_group's packaging aspects; see runfiles_groups.bzl.
+        "_aspect_rule_hints": attr.label_list(
+            default = ["//python/private:py_runtime_pair_runfiles_group_describer"],
+        ),
+        "_runfiles_group_attrs": attr.string_list(default = []),
         "_visible_for_testing": attr.label(
             default = labels.VISIBLE_FOR_TESTING,
         ),