refacto(cli): change restart by subprocess

because of Windows OS not being able to restart process we relly on calling a subprocess instead.

See python/cpython#63323

knots_hub/cli.py

@@ -3,6 +3,7 @@
 import json
 import logging
 import os
+import subprocess
 import sys
 import webbrowser
 from typing import Type
@@ -117,6 +118,11 @@ def execute(self):
         local_install_path = self._config.local_install_path
         is_runtime_local = is_runtime_from_local_install(local_install_path)
 
+        # we restart to the local install for performance consideration.
+        # And we force to start by the remote as it's always the latest version,
+        # while local may be an older version which will have issue reading more
+        # up-to date configs and similar.
+
         if not is_runtime_local:
 
             # an empty installer path imply the hub is never installed/updated locally
@@ -285,11 +291,17 @@ def _restart_hub(self, exe: str):
             restarted_amount=self._restarted,
         )
 
-        LOGGER.info(f"restarting hub '{exe}' ...")
-        # safety mentioned in the doc
-        sys.stdout.flush()
-        LOGGER.debug(f"os.execv({exe},{argv})")
-        os.execv(exe, argv)
+        command = [exe] + argv[1:]
+
+        # this is an undocumented env var only used for internal testing
+        asshell: bool = bool(os.getenv("KNOTS_HUB_RESTART_AS_SHELL", False))
+
+        LOGGER.info(f"restarting hub to '{exe}' (asshell={asshell}) ...")
+        LOGGER.debug(f"subprocess.run({command})")
+        # XXX: we use subprocess instead of os.execv because the implementation on Windows
+        #   is not a real restart https://github.com/python/cpython/issues/63323.
+        result = subprocess.run(command, shell=asshell)
+        sys.exit(result.returncode)
 
 
 class _Parser(BaseParser):

tests/test_end2end.py

@@ -77,7 +77,7 @@ def test__main__full(monkeypatch, data_dir, tmp_path, caplog):
     with vendor_config_path.open("w") as file:
         json.dump(vendor_config, file, indent=4)
 
-    class ExecvPatcher:
+    class SubprocessPatcher:
 
         exe: Path = None
         args: List[str] = None
@@ -90,16 +90,16 @@ def clear(cls):
             cls.called = False
 
         @classmethod
-        def _patch_os_execv(cls, exe, args):
-            exe = Path(exe)
+        def _patch(cls, command, *args, **kwargs):
+            exe = Path(command[0])
             cls.called = True
             cls.exe = exe
-            cls.args = args
+            cls.args = command[1:]
 
     def _patch_sys_argv():
         return sys.argv.copy() + ["UNWANTEDARG"]
 
-    monkeypatch.setattr(os, "execv", ExecvPatcher._patch_os_execv)
+    monkeypatch.setattr(subprocess, "run", SubprocessPatcher._patch)
     monkeypatch.setattr(sys, "argv", _patch_sys_argv)
 
     monkeypatch.setenv(knots_hub.Environ.USER_INSTALL_PATH, str(install_dir))
@@ -122,8 +122,8 @@ def _patch_sys_argv():
 
     expected_local_exe = install_dir / exe_name
     assert expected_local_exe.exists()
-    assert ExecvPatcher.called is True
-    assert ExecvPatcher.exe == expected_local_exe
+    assert SubprocessPatcher.called is True
+    assert SubprocessPatcher.exe == expected_local_exe
 
     # check the vendor install system
 
@@ -164,29 +164,29 @@ def _patched_is_runtime_from_local_install(*args):
         _patched_is_runtime_from_local_install,
     )
 
-    argv = ExecvPatcher.args.copy()[1:]
-    ExecvPatcher.clear()
+    argv = SubprocessPatcher.args.copy()[1:]
+    SubprocessPatcher.clear()
     with pytest.raises(SystemExit):
         knots_hub.__main__.main(argv=argv)
 
-    assert ExecvPatcher.called is False
+    assert SubprocessPatcher.called is False
     assert InstallRezPatcher.called is True
     assert InstallPythonPatcher.called is True
     assert vendor_install_dir.exists()
     assert rez_install_dir.exists()
 
     # check no install
 
-    ExecvPatcher.clear()
+    SubprocessPatcher.clear()
     InstallRezPatcher.called = False
     InstallPythonPatcher.called = False
 
     argv = ["--restarted", "1"]
-    ExecvPatcher.clear()
+    SubprocessPatcher.clear()
     with pytest.raises(SystemExit):
         knots_hub.__main__.main(argv=argv)
 
-    assert ExecvPatcher.called is False
+    assert SubprocessPatcher.called is False
     assert InstallRezPatcher.called is False
     assert InstallPythonPatcher.called is False
 
@@ -206,16 +206,16 @@ def _patched_is_runtime_from_local_install(*args):
     with vendor_config_path.open("w") as file:
         json.dump(vendor_config, file, indent=4)
 
-    ExecvPatcher.clear()
+    SubprocessPatcher.clear()
     InstallRezPatcher.called = False
     InstallPythonPatcher.called = False
 
     argv = ["--restarted", "1"]
-    ExecvPatcher.clear()
+    SubprocessPatcher.clear()
     with pytest.raises(SystemExit):
         knots_hub.__main__.main(argv=argv)
 
-    assert ExecvPatcher.called is False
+    assert SubprocessPatcher.called is False
     assert InstallRezPatcher.called is True
     assert InstallPythonPatcher.called is True
 
@@ -228,7 +228,8 @@ def _patched_is_runtime_from_local_install(*args):
     # check uninstall
 
     def _patch_execv(exe_: str, argv_: List[str]):
-        subprocess.run([exe_] + argv_[1:], check=True)
+        # we patch subprocess.run above so use a different function
+        subprocess.check_call([exe_] + argv_[1:])
 
     monkeypatch.setattr(os, "execv", _patch_execv)