fix(reconciliation): implement UUID-based domain reconciliation and connection safety

computes/utils.py

@@ -1,17 +1,64 @@
+import logging
+from django.db import transaction
 from instances.models import Instance
 
+logger = logging.getLogger(__name__)
+
 
 def refresh_instance_database(compute):
-    domains = compute.proxy.wvm.listAllDomains()
-    domain_names = [d.name() for d in domains]
-    domain_uuids = [d.UUIDString() for d in domains]
-    # Delete instances that're not on host from DB
-    Instance.objects.filter(compute=compute).exclude(name__in=domain_names).delete()
-    Instance.objects.filter(compute=compute).exclude(uuid__in=domain_uuids).delete()
-    # Create instances that're on host but not in DB
-    names = Instance.objects.filter(compute=compute).values_list("name", flat=True)
-    for domain in domains:
-        if domain.name() not in names:
-            Instance(
-                compute=compute, name=domain.name(), uuid=domain.UUIDString()
-            ).save()
+    """
+    Synchronizes the WebVirtCloud database with libvirt domain state.
+    Libvirt is the single source of truth:
+      - VMs removed in virt-manager/virsh are deleted from the database.
+      - VMs created in virt-manager/virsh are added to the database.
+      - VMs renamed in virt-manager/virsh have their name updated without losing
+        UserInstance permission relationships (matched by UUID).
+      - If libvirt is unreachable (connection/network error), the database is left
+        untouched to avoid false deletions.
+    """
+    try:
+        if hasattr(compute, "status") and compute.status is False:
+            return
+        domains = compute.proxy.wvm.listAllDomains()
+    except Exception as e:
+        logger.warning(
+            "Failed to retrieve domains from compute %s (%s): %s",
+            getattr(compute, "name", compute),
+            getattr(compute, "hostname", ""),
+            e,
+        )
+        return
+
+    # Map libvirt UUIDs to current domain names
+    host_domains = {}
+    for d in domains:
+        try:
+            host_domains[d.UUIDString()] = d.name()
+        except Exception as e:
+            logger.warning(
+                "Error reading domain metadata from compute %s: %s",
+                getattr(compute, "name", compute),
+                e,
+            )
+            # If we fail to read a domain's metadata, abort sync to prevent accidental deletion
+            return
+
+    db_instances = Instance.objects.filter(compute=compute)
+    db_uuids = set(db_instances.values_list("uuid", flat=True))
+
+    with transaction.atomic():
+        # 1. Update name for any VM whose name changed out-of-band in virsh/virt-manager
+        for inst in db_instances:
+            if inst.uuid in host_domains:
+                new_name = host_domains[inst.uuid]
+                if inst.name != new_name:
+                    inst.name = new_name
+                    inst.save(update_fields=["name"])
+
+        # 2. Delete instances that were genuinely undefined/deleted in virsh/virt-manager
+        db_instances.exclude(uuid__in=host_domains.keys()).delete()
+
+        # 3. Create new instances that were created out-of-band in virsh/virt-manager
+        for uuid, name in host_domains.items():
+            if uuid not in db_uuids:
+                Instance.objects.create(compute=compute, name=name, uuid=uuid)