pin setuptools<82 in pip packaging command to prevent pkg_resources removal

python/rpdk/python/codegen.py

@@ -322,6 +322,7 @@ def _make_pip_command(base_path):
             str(base_path / "requirements.txt"),
             "--target",
             str(base_path / "build"),
+            "setuptools<82",
         ]
 
     @staticmethod
@@ -399,9 +400,15 @@ def _pip_build(cls, base_path):
         LOG.warning("Starting pip build.")
         try:
             # On windows run pip command through the default shell (CMD)
+            # Build a quoted string so CMD doesn't misinterpret '<' or '>'
+            # in version specifiers (e.g. 'setuptools<82') as redirection.
             if os.name == "nt":
+                cmd_str = " ".join(
+                    f'"{a}"' if any(c in a for c in ("<", ">", "&", "|")) else a
+                    for a in command
+                )
                 completed_proc = subprocess_run(  # nosec
-                    command,
+                    cmd_str,
                     stdout=PIPE,
                     stderr=PIPE,
                     cwd=base_path,

python/rpdk/python/templates/requirements.txt

@@ -1 +1,2 @@
 {{ support_lib_name }}>=2.1.9
+setuptools<82

setup.py

@@ -40,7 +40,7 @@ def find_version(*file_paths):
     install_requires=[
         "cloudformation-cli>=0.2.26",
         "types-dataclasses>=0.1.5",
-        "setuptools",
+        "setuptools<82",
     ],
     entry_points={
         "rpdk.v1.languages": [

tests/plugin/codegen_test.py

@@ -540,6 +540,27 @@ def test__pip_build_called_process_error(tmp_path):
     assert isinstance(excinfo.value.__cause__, (FileNotFoundError, CalledProcessError))
 
 
+def test__pip_build_windows_quotes_version_specifiers(tmp_path):
+    """On Windows, args with '<' must be quoted so CMD doesn't misinterpret them."""
+    command = ["pip", "install", "setuptools<82"]
+    patch_cmd = patch.object(
+        PythonLanguagePlugin, "_make_pip_command", return_value=command
+    )
+    patch_os = patch("rpdk.python.codegen.os.name", "nt")
+    patch_run = patch("rpdk.python.codegen.subprocess_run", autospec=True)
+
+    with patch_cmd, patch_os, patch_run as mock_run:
+        PythonLanguagePlugin._pip_build(tmp_path)
+
+    call_args = mock_run.call_args
+    cmd_arg = call_args[0][0]
+    assert isinstance(
+        cmd_arg, str
+    ), "Windows branch must pass a string to subprocess_run"
+    assert "setuptools<82" in cmd_arg
+    assert call_args[1]["shell"] is True
+
+
 def test__build_pip(plugin):
     plugin._use_docker = False
     plugin._no_docker = True
@@ -553,6 +574,17 @@ def test__build_pip(plugin):
     mock_pip.assert_called_once_with(sentinel.base_path)
 
 
+def test__make_pip_command_pins_setuptools_lt_82(tmp_path):
+    """setuptools<82 must be in the pip command to prevent pkg_resources removal."""
+    cmd = PythonLanguagePlugin._make_pip_command(tmp_path)
+    assert "setuptools<82" in cmd, (
+        "setuptools<82 must be pinned in pip command — setuptools 82+ removes "
+        "pkg_resources which breaks cloudformation-cli-python-lib at runtime"
+    )
+    assert str(tmp_path / "requirements.txt") in cmd
+    assert str(tmp_path / "build") in cmd
+
+
 def test__build_pip_posix(plugin):
     patch_os_name = patch("rpdk.python.codegen.os.name", "posix")
     patch_subproc = patch("rpdk.python.codegen.subprocess_run")
@@ -581,7 +613,10 @@ def test__build_pip_windows(plugin):
         plugin._pip_build(temppath)
 
     mock_subproc.assert_called_once_with(
-        plugin._make_pip_command(temppath),
+        " ".join(
+            f'"{a}"' if any(c in a for c in ("<", ">", "&", "|")) else a
+            for a in plugin._make_pip_command(temppath)
+        ),
         stdout=ANY,
         stderr=ANY,
         cwd=temppath,