feat: add requires_file for py_wheel and update docs

python/packaging.bzl

@@ -188,6 +188,12 @@ def _py_wheel_impl(ctx):
 
     if ctx.attr.python_requires:
         metadata_contents.append("Requires-Python: %s" % ctx.attr.python_requires)
+
+    if len(ctx.attr.requires) == 0 and ctx.attr.requires_file:
+        requires_file = ctx.file.requires_file
+        args.add("--requires_file", requires_file)
+        other_inputs.append(requires_file)
+
     for requirement in ctx.attr.requires:
         metadata_contents.append("Requires-Dist: %s" % requirement)
 
@@ -351,6 +357,13 @@ _requirement_attrs = {
                "[Declaring required dependency](https://setuptools.readthedocs.io/en/latest/userguide/dependency_management.html#declaring-dependencies) " +
                "for details and examples of the format of this argument."),
     ),
+    "requires_file": attr.label(
+        doc = (
+            "Requirements file for list of requirements for this package." +
+            "If set `requires`, this flag will be ignored.",
+        )
+        allow_single_file = True,
+    ),
 }
 
 _entrypoint_attrs = {

tools/wheelmaker.py

@@ -258,6 +258,12 @@ def parse_args() -> argparse.Namespace:
     metadata_group.add_argument(
         "--platform", type=str, default="any", help="Target platform. "
     )
+    metadata_group.add_argument(
+        "--requires_file",
+        type=Path,
+        default="",
+        help="Requirements file for list of requirements for this package",
+    )
 
     output_group = parser.add_argument_group("Output file location")
     output_group.add_argument(
@@ -398,6 +404,9 @@ def main() -> None:
                       encoding="utf-8") as metadata_file:
                 metadata = metadata_file.read()
 
+        if arguments.requires_file:
+            with open(arguments.requires_file) as fp:
+                metadata += "\n" + fp.read().strip().split("\n")
         maker.add_metadata(metadata=metadata, description=description)
 
         if arguments.entry_points_file: