fix(instances): a DRBD status the compute did not tell is Unknown, not None DRBD

A drbdadm query that timed out, could not start ssh or failed showed
"None DRBD", as for a VM without DRBD resources. It now shows Unknown,
in the same red badge as a DRBD status that is not OK.

instances/tests/test_drbd_target.py

@@ -1,6 +1,7 @@
 """drbd_status runs ssh with the compute's login@hostname; a compute whose
 values would inject an ssh option (an existing or bypassed row) is skipped,
-and a compute that does not answer in time leaves the status unknown."""
+and a compute that does not answer in time, or an ssh that fails, leaves
+the status unknown, not "None DRBD"."""
 
 import subprocess
 import unittest
@@ -24,9 +25,16 @@ class DrbdTargetTestCase(unittest.TestCase):
         with patch("instances.views.get_instance", return_value=vm), patch(
             "instances.views.subprocess.run", side_effect=subprocess.TimeoutExpired("ssh", DRBD_STATUS_TIMEOUT)
         ) as run:
-            self.assertEqual(drbd_status(SimpleNamespace(user=None), 1), "None DRBD")
+            self.assertEqual(drbd_status(SimpleNamespace(user=None), 1), "Unknown")
         self.assertEqual(run.call_args.kwargs["timeout"], DRBD_STATUS_TIMEOUT)
 
+    def test_a_failed_ssh_leaves_the_status_unknown(self):
+        vm = SimpleNamespace(name="vm1", compute=SimpleNamespace(type=2, login="root", hostname="192.0.2.1"))
+        with patch("instances.views.get_instance", return_value=vm), patch(
+            "instances.views.subprocess.run", return_value=SimpleNamespace(returncode=255, stdout="")
+        ):
+            self.assertEqual(drbd_status(SimpleNamespace(user=None), 1), "Unknown")
+
 
 STATUS = """webserver role:Primary
   disk:UpToDate
@@ -41,7 +49,7 @@ class DrbdStatusTestCase(unittest.TestCase):
     def status(self, name, stdout=STATUS):
         vm = SimpleNamespace(name=name, compute=SimpleNamespace(type=2, login="root", hostname="192.0.2.1"))
         with patch("instances.views.get_instance", return_value=vm), patch(
-            "instances.views.subprocess.run", return_value=SimpleNamespace(stdout=stdout)
+            "instances.views.subprocess.run", return_value=SimpleNamespace(returncode=0, stdout=stdout)
         ):
             return drbd_status(SimpleNamespace(user=None), 1)
 

instances/views.py

@@ -415,8 +415,10 @@ def drbd_status(request, pk):
                 text=True,
                 timeout=DRBD_STATUS_TIMEOUT,
             )
-        except subprocess.TimeoutExpired:
-            return result
+        except (subprocess.TimeoutExpired, OSError):
+            return _("Unknown")  # not "None DRBD": the compute did not tell
+        if remoteDrbdStatus.returncode != 0:
+            return _("Unknown")
 
         # the VM's resources are its name or its name_SUFFIX, at the start of a line
         instanceFindDrbd = re.compile(