[DPE-5306] Data Interafces v40 (#615)

* Data Interafces v40

* Adjustments on unittests

* Fix on charm code not to publish before relation is fully established

* Don't set uri if no database or password

* Unit test

---------

Co-authored-by: Dragomir Penev <[email protected]>

lib/charms/data_platform_libs/v0/data_interfaces.py

@@ -331,7 +331,7 @@ def _on_topic_requested(self, event: TopicRequestedEvent):
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 39
+LIBPATCH = 40
 
 PYDEPS = ["ops>=2.0.0"]
 
@@ -391,6 +391,10 @@ class IllegalOperationError(DataInterfacesError):
     """To be used when an operation is not allowed to be performed."""
 
 
+class PrematureDataAccessError(DataInterfacesError):
+    """To be raised when the Relation Data may be accessed (written) before protocol init complete."""
+
+
 ##############################################################################
 # Global helpers / utilities
 ##############################################################################
@@ -1453,6 +1457,8 @@ def _on_relation_changed_event(self, event: RelationChangedEvent) -> None:
 class ProviderData(Data):
     """Base provides-side of the data products relation."""
 
+    DATABASE_FIELD = "database"
+
     def __init__(
         self,
         model: Model,
@@ -1618,6 +1624,15 @@ def _fetch_my_specific_relation_data(
     def _update_relation_data(self, relation: Relation, data: Dict[str, str]) -> None:
         """Set values for fields not caring whether it's a secret or not."""
         req_secret_fields = []
+
+        keys = set(data.keys())
+        if self.fetch_relation_field(relation.id, self.DATABASE_FIELD) is None and (
+            keys - {"endpoints", "read-only-endpoints", "replset"}
+        ):
+            raise PrematureDataAccessError(
+                "Premature access to relation data, update is forbidden before the connection is initialized."
+            )
+
         if relation.app:
             req_secret_fields = get_encoded_list(relation, relation.app, REQ_SECRET_FIELDS)
 
@@ -3290,6 +3305,8 @@ class KafkaRequiresEvents(CharmEvents):
 class KafkaProviderData(ProviderData):
     """Provider-side of the Kafka relation."""
 
+    DATABASE_FIELD = "topic"
+
     def __init__(self, model: Model, relation_name: str) -> None:
         super().__init__(model, relation_name)
 
@@ -3539,6 +3556,8 @@ class OpenSearchRequiresEvents(CharmEvents):
 class OpenSearchProvidesData(ProviderData):
     """Provider-side of the OpenSearch relation."""
 
+    DATABASE_FIELD = "index"
+
     def __init__(self, model: Model, relation_name: str) -> None:
         super().__init__(model, relation_name)
 

src/relations/postgresql_provider.py

@@ -194,6 +194,8 @@ def update_endpoints(self, event: DatabaseRequestedEvent = None) -> None:
             user = f"relation-{relation_id}"
             database = rel_data[relation_id].get("database")
             password = secret_data.get(relation_id, {}).get("password")
+            if not database or not password:
+                continue
 
             # Set the read/write endpoint.
             self.database_provides.set_endpoints(

tests/unit/test_postgresql_provider.py

@@ -281,18 +281,35 @@ def test_update_endpoints_without_event(harness):
             "relations.postgresql_provider.DatabaseProvides.fetch_my_relation_data"
         ) as _fetch_my_relation_data,
     ):
-        _fetch_my_relation_data.return_value.get().get.return_value = "test_password"
-
         # Mock the members_ips list to simulate different scenarios
         # (with and without a replica).
-        _members_ips.side_effect = [{"1.1.1.1", "2.2.2.2"}, {"1.1.1.1"}]
+        _members_ips.side_effect = [{"1.1.1.1", "2.2.2.2"}, {"1.1.1.1", "2.2.2.2"}, {"1.1.1.1"}]
         rel_id = harness.model.get_relation(RELATION_NAME).id
 
+        # Don't set data if no password
+        _fetch_my_relation_data.return_value.get().get.return_value = None
+
+        harness.charm.postgresql_client_relation.update_endpoints()
+        assert harness.get_relation_data(rel_id, harness.charm.app.name) == {}
+
+        _fetch_my_relation_data.reset_mock()
+        _fetch_my_relation_data.return_value.get().get.return_value = "test_password"
+
         # Add two different relations.
         rel_id = harness.add_relation(RELATION_NAME, "application")
         another_rel_id = harness.add_relation(RELATION_NAME, "application")
 
+        relation_ids = [rel.id for rel in harness.charm.model.relations[RELATION_NAME]]
+        other_rel_ids = set(relation_ids) - set({rel_id, another_rel_id})
+
         with harness.hooks_disabled():
+            for relation_id in other_rel_ids:
+                harness.update_relation_data(
+                    relation_id,
+                    "application",
+                    {"database": "some_db", "extra-user-roles": ""},
+                )
+
             harness.update_relation_data(
                 rel_id,
                 "application",