[DPE-4230] - fix: sort endpoints so not constantly updating (#270)

Fixes #269, I
think

lib/charms/opensearch/v0/opensearch_relation_provider.py

@@ -59,7 +59,7 @@
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 2
+LIBPATCH = 3
 
 logger = logging.getLogger(__name__)
 
@@ -418,7 +418,7 @@ def update_endpoints(self, relation: Relation, omit_endpoints: Optional[Set[str]
             ips = set()
 
         port = self.opensearch.port
-        endpoints = ",".join([f"{ip}:{port}" for ip in ips - omit_endpoints])
+        endpoints = ",".join(sorted([f"{ip}:{port}" for ip in ips - omit_endpoints]))
         databag_endpoints = relation.data[relation.app].get("endpoints")
 
         if endpoints != databag_endpoints:

tests/unit/lib/test_opensearch_relation_provider.py

@@ -252,14 +252,16 @@ def test_on_relation_broken(self, _, __, _is_node_up, _remove_users, _unit_depar
     @patch("charm.OpenSearchOperatorCharm._purge_users")
     def test_update_endpoints(self, _, __, _nodes, _is_node_up, _set_endpoints):
         self.harness.set_leader(True)
-        node = MagicMock()
-        node.ip = "4.4.4.4"
-        _nodes.return_value = [node]
+        node1 = MagicMock()
+        node1.ip = "4.4.4.4"
+        node2 = MagicMock()
+        node2.ip = "5.5.5.5"
+        _nodes.return_value = [node2, node1]  # out of order
         relation = MagicMock()
         relation.id = 1
         endpoints = [f"{node.ip}:{self.charm.opensearch.port}" for node in _nodes.return_value]
         self.opensearch_provider.update_endpoints(relation)
-        _set_endpoints.assert_called_with(relation.id, ",".join(endpoints))
+        _set_endpoints.assert_called_with(relation.id, ",".join(sorted(endpoints)))
 
     def add_dashboard_relation(self):
         opensearch_relation = self.harness.add_relation(