fix(instances): a VM's DRBD status counts only its own resources

The resource pattern was not anchored and took any letters after the VM's
name, so VM "web" also counted "webserver" and "myweb"; a VM with no
resource of its own got "Secondary/OK", stored on every page view. A
VM's resources are now its name or name_SUFFIX at the start of a line,
and a VM without one is "None DRBD".

instances/tests/test_drbd_target.py

@@ -26,3 +26,29 @@ class DrbdTargetTestCase(unittest.TestCase):
         ) as run:
             self.assertEqual(drbd_status(SimpleNamespace(user=None), 1), "None DRBD")
         self.assertEqual(run.call_args.kwargs["timeout"], DRBD_STATUS_TIMEOUT)
+
+
+STATUS = """webserver role:Primary
+  disk:UpToDate
+web role:Secondary
+  disk:UpToDate
+web_data role:Secondary
+  disk:Outdated
+"""
+
+
+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)
+        ):
+            return drbd_status(SimpleNamespace(user=None), 1)
+
+    def test_a_vm_counts_only_its_own_resources(self):
+        # "webserver" is another VM's resource; "web_data" is web's second disk
+        self.assertEqual(self.status("web"), "Secondary/NOK")
+        self.assertEqual(self.status("webserver"), "Primary/OK")
+
+    def test_a_vm_without_a_resource_has_no_drbd(self):
+        self.assertEqual(self.status("db"), "None DRBD")

instances/views.py

@@ -341,13 +341,13 @@ def drbd_status(request, pk):
         except subprocess.TimeoutExpired:
             return result
 
-        if remoteDrbdStatus.stdout:
-            instanceFindDrbd = re.compile(
-                re.escape(instance.name) + "[_]*[A-Z]* role:(.+?)\n  disk:(.+?)\n",
-                re.IGNORECASE,
-            )
-            instanceDrbd = instanceFindDrbd.findall(remoteDrbdStatus.stdout)
-
+        # the VM's resources are its name or its name_SUFFIX, at the start of a line
+        instanceFindDrbd = re.compile(
+            "^" + re.escape(instance.name) + "(?:_[A-Z]+)? role:(.+?)\n  disk:(.+?)\n",
+            re.IGNORECASE | re.MULTILINE,
+        )
+        instanceDrbd = instanceFindDrbd.findall(remoteDrbdStatus.stdout or "")
+        if instanceDrbd:
             primaryCount = 0
             secondaryCount = 0
             statusDisk = "OK"