pacemaker: write preferred_host as its own constraint

tests/test_pacemaker.py

@@ -313,9 +313,17 @@ def test_pin_location_names_the_constraint(self, p, crm):
             "hyp1",
         ]
 
-    def test_default_location_moves_the_resource(self, p, crm):
+    def test_default_location_names_the_constraint(self, p, crm):
         p.default_location("hyp1")
-        assert crm.command == ["crm", "resource", "move", RESOURCE, "hyp1"]
+        assert crm.command == [
+            "crm",
+            "configure",
+            "location",
+            "seapath-preferred-vm1",
+            RESOURCE,
+            "inf:",
+            "hyp1",
+        ]
 
 
 class TestAddColocation:

vm_manager/helpers/pacemaker.py

@@ -346,12 +346,19 @@ def default_location(self, node):
         Set the VM default location.
 
         The VM will be deployed on the given node unless the node is up.
+
+        Written as a constraint of its own rather than with
+        `crm resource move`, whose `cli-prefer-` constraint is
+        indistinguishable from a manual move and is removed by
+        `crm resource clear`.
         """
         args = [
             "crm",
-            "resource",
-            "move",
+            "configure",
+            "location",
+            f"seapath-preferred-{self._resource}",
             self._resource,
+            "inf:",
             node,
         ]