From 718b96ba429616534897b071a8a29b84fb6a0196 Mon Sep 17 00:00:00 2001
From: Paulo Machado <paulo.machado@canonical.com>
Date: Sat, 27 Apr 2024 21:54:48 -0300
Subject: [PATCH] first pass

---
 .../data_platform_libs/v0/data_interfaces.py  | 34 ++++++++++++++++---
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/lib/charms/data_platform_libs/v0/data_interfaces.py b/lib/charms/data_platform_libs/v0/data_interfaces.py
index d46770f0..18d32af1 100644
--- a/lib/charms/data_platform_libs/v0/data_interfaces.py
+++ b/lib/charms/data_platform_libs/v0/data_interfaces.py
@@ -307,6 +307,7 @@ def _on_topic_requested(self, event: TopicRequestedEvent):
     Optional,
     Set,
     Tuple,
+    TypedDict,
     Union,
     ValuesView,
 )
@@ -331,7 +332,7 @@ 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 = 34
+LIBPATCH = 35
 
 PYDEPS = ["ops>=2.0.0"]
 
@@ -1306,6 +1307,8 @@ def _on_relation_changed_event(self, event: RelationChangedEvent) -> None:
         raise NotImplementedError
 
 
+HostnameMapping = TypedDict("HostnameMapping", {"address": str, "names": List[str]})
+
 # Base ProviderData and RequiresData
 
 
@@ -2277,7 +2280,7 @@ def __init__(
 
 
 ################################################################################
-# Cross-charm Relatoins Data Handling and Evenets
+# Cross-charm Relations Data Handling and Events
 ################################################################################
 
 # Generic events
@@ -2300,7 +2303,7 @@ class RelationEventWithSecret(RelationEvent):
 
     @property
     def _secrets(self) -> dict:
-        """Caching secrets to avoid fetching them each time a field is referrd.
+        """Caching secrets to avoid fetching them each time a field is referred.
 
         DON'T USE the encapsulated helper variable outside of this function
         """
@@ -2309,7 +2312,7 @@ def _secrets(self) -> dict:
         return self._cached_secrets
 
     def _get_secret(self, group) -> Optional[Dict[str, str]]:
-        """Retrieveing secrets."""
+        """Retrieving secrets."""
         if not self.app:
             return
         if not self._secrets.get(group):
@@ -2498,6 +2501,18 @@ def version(self) -> Optional[str]:
 
         return self.relation.data[self.relation.app].get("version")
 
+    @property
+    def hostname_mapping(self) -> Optional[List[HostnameMapping]]:
+        """Returns the hostname mapping.
+
+        A list that maps the hostnames to IP address.
+        """
+        if not self.relation.app:
+            return None
+
+        if mapping := self.relation.data[self.relation.app].get("hostname-mapping"):
+            return json.loads(mapping)
+
 
 class DatabaseCreatedEvent(AuthenticationEvent, DatabaseRequiresEvent):
     """Event emitted when a new database is created for use on this relation."""
@@ -2602,6 +2617,17 @@ def set_version(self, relation_id: int, version: str) -> None:
         """
         self.update_relation_data(relation_id, {"version": version})
 
+    def set_hostname_mapping(
+        self, relation_id: int, hostname_mapping: List[HostnameMapping]
+    ) -> None:
+        """Set hostname mapping.
+
+        Args:
+            relation_id: the identifier for a particular relation.
+            hostname_mapping: list of hostname mapping.
+        """
+        self.update_relation_data(relation_id, {"hostname-mapping": json.dumps(hostname_mapping)})
+
 
 class DatabaseProviderEventHandlers(EventHandlers):
     """Provider-side of the database relation handlers."""