fox: use a strategic merge patch

magnum_cluster_api/resources.py

@@ -146,18 +146,33 @@ def __init__(self, api: pykube.HTTPClient, namespace="magnum-system"):
 
     def apply(self) -> None:
         resource = self.get_object()
-        resp = resource.api.patch(
-            **resource.api_kwargs(
-                headers={
-                    "Content-Type": "application/apply-patch+yaml",
-                },
-                params={
-                    "fieldManager": "atmosphere-operator",
-                    "force": True,
-                },
-                data=json.dumps(resource.obj),
+
+        # Check if resource exists
+        existing_resource = resource.api.get(**resource.api_kwargs())
+        exists = existing_resource.status_code == 200
+
+        if not exists:
+            # Create new resource with server-side apply
+            resp = resource.api.patch(
+                **resource.api_kwargs(
+                    headers={
+                        "Content-Type": "application/apply-patch+yaml",
+                    },
+                    params={
+                        "fieldManager": "atmosphere-operator",
+                        "force": True,
+                    },
+                    data=json.dumps(resource.obj),
+                )
+            )
+        else:
+            # Update existing resource with Strategic Merge Patch
+            resp = resource.api.patch(
+                **resource.api_kwargs(
+                    headers={"Content-Type": "application/merge-patch+json"},
+                    data=json.dumps(resource.obj),
+                )
             )
-        )
 
         resource.api.raise_for_status(resp)
         resource.set_obj(resp.json())