Handle sigterm by killing the commands subprocess

docs/changelog/1772.bugfix.rst

@@ -0,0 +1,2 @@
+Fix a killed tox (via SIGTERM) leaving the commands subprocesses running
+by handling it as if it were a KeyboardInterrupt - by :user:`dajose`

docs/config.rst

@@ -607,9 +607,9 @@ Complete list of settings that you can put into ``testenv*`` sections:
 
     .. versionadded:: 3.15.2
 
-    When an interrupt is sent via Ctrl+C, the SIGINT is sent to all foreground
-    processes. The :conf:``suicide_timeout`` gives the running process time to
-    cleanup and exit before receiving (in some cases, a duplicate) SIGINT from
+    When an interrupt is sent via Ctrl+C or the tox process is killed with a SIGTERM,
+    a SIGINT is sent to all foreground processes. The :conf:``suicide_timeout`` gives
+    the running process time to cleanup and exit before receiving (in some cases, a duplicate) SIGINT from
     tox.
 
 .. conf:: interrupt_timeout ^ float ^ 0.3

src/tox/action.py

@@ -49,6 +49,10 @@ def __init__(
         self.suicide_timeout = suicide_timeout
         self.interrupt_timeout = interrupt_timeout
         self.terminate_timeout = terminate_timeout
+        if is_main_thread():
+            # python allows only main thread to install signal handlers
+            # see https://docs.python.org/3/library/signal.html#signals-and-threads
+            self._install_sigterm_handler()
 
     def __enter__(self):
         msg = "{} {}".format(self.msg, " ".join(map(str, self.args)))
@@ -278,3 +282,12 @@ def _rewrite_args(self, cwd, args):
             new_args.append(str(arg))
 
         return new_args
+
+    def _install_sigterm_handler(self):
+        """Handle sigterm as if it were a keyboardinterrupt"""
+
+        def sigterm_handler(signum, frame):
+            reporter.error("Got SIGTERM, handling it as a KeyboardInterrupt")
+            raise KeyboardInterrupt()
+
+        signal.signal(signal.SIGTERM, sigterm_handler)

tests/integration/test_provision_int.py

@@ -73,7 +73,8 @@ def test_provision_from_pyvenv(initproj, cmd, monkeypatch):
     "sys.platform == 'win32'",
     reason="triggering SIGINT reliably on Windows is hard",
 )
-def test_provision_interrupt_child(initproj, monkeypatch, capfd):
+@pytest.mark.parametrize("signal_type", [signal.SIGINT, signal.SIGTERM])
+def test_provision_interrupt_child(initproj, monkeypatch, capfd, signal_type):
     monkeypatch.delenv(str("PYTHONPATH"), raising=False)
     monkeypatch.setenv(str("TOX_REPORTER_TIMESTAMP"), str("1"))
     initproj(
@@ -123,7 +124,7 @@ def test_provision_interrupt_child(initproj, monkeypatch, capfd):
         # 1 process for the host tox, 1 for the provisioned
         assert len(all_process) >= 2, all_process
 
-    process.send_signal(signal.CTRL_C_EVENT if sys.platform == "win32" else signal.SIGINT)
+    process.send_signal(signal.CTRL_C_EVENT if sys.platform == "win32" else signal_type)
     process.communicate()
     out, err = capfd.readouterr()
     assert ".tox KeyboardInterrupt: from" in out, out