fix: Hydrate infra object in the sql registry proto() method

sdk/python/feast/infra/registry_stores/sql.py

@@ -148,6 +148,15 @@
 )
 
 
+feast_metadata = Table(
+    "feast_metadata",
+    metadata,
+    Column("metadata_key", String(50), primary_key=True),
+    Column("metadata_value", String(50), nullable=False),
+    Column("last_updated_timestamp", BigInteger, nullable=False),
+)
+
+
 class SqlRegistry(BaseRegistry):
     def __init__(
         self, registry_config: Optional[RegistryConfig], repo_path: Optional[Path]
@@ -575,7 +584,6 @@ def get_user_metadata(
     def proto(self) -> RegistryProto:
         r = RegistryProto()
         project = ""
-        # TODO(achal): Support Infra object, and last_updated_timestamp.
         for lister, registry_proto_field in [
             (self.list_entities, r.entities),
             (self.list_feature_views, r.feature_views),
@@ -591,6 +599,11 @@ def proto(self) -> RegistryProto:
             if objs:
                 registry_proto_field.extend([obj.to_proto() for obj in objs])
 
+        r.infra.CopyFrom(self.get_infra(project).to_proto())
+        last_updated_timestamp = self._get_last_updated_metadata()
+        if last_updated_timestamp:
+            r.last_updated.FromDatetime(last_updated_timestamp)
+
         return r
 
     def commit(self):
@@ -626,13 +639,15 @@ def _apply_object(self, table, id_field_name, obj, proto_field_name, name=None):
                 }
                 insert_stmt = insert(table).values(values,)
                 conn.execute(insert_stmt)
+            self._set_last_updated_metadata(update_datetime)
 
     def _delete_object(self, table, name, project, id_field_name, not_found_exception):
         with self.engine.connect() as conn:
             stmt = delete(table).where(getattr(table.c, id_field_name) == name)
             rows = conn.execute(stmt)
             if rows.rowcount < 1 and not_found_exception:
                 raise not_found_exception(name, project)
+            self._set_last_updated_metadata(datetime.utcnow())
             return rows.rowcount
 
     def _get_object(
@@ -666,3 +681,40 @@ def _list_objects(self, table, proto_class, python_class, proto_field_name):
                     for row in rows
                 ]
         return []
+
+    def _set_last_updated_metadata(self, last_updated: datetime):
+        with self.engine.connect() as conn:
+            stmt = select(feast_metadata).where(
+                feast_metadata.c.metadata_key == "last_updated_timestamp"
+            )
+            row = conn.execute(stmt).first()
+
+            update_time = int(last_updated.timestamp())
+
+            values = {
+                "metadata_key": "last_updated_timestamp",
+                "metadata_value": f"{update_time}",
+                "last_updated_timestamp": update_time,
+            }
+            if row:
+                update_stmt = (
+                    update(feast_metadata)
+                    .where(feast_metadata.c.metadata_key == "last_updated_timestamp")
+                    .values(values)
+                )
+                conn.execute(update_stmt)
+            else:
+                insert_stmt = insert(feast_metadata).values(values,)
+                conn.execute(insert_stmt)
+
+    def _get_last_updated_metadata(self):
+        with self.engine.connect() as conn:
+            stmt = select(feast_metadata).where(
+                feast_metadata.c.metadata_key == "last_updated_timestamp"
+            )
+            row = conn.execute(stmt).first()
+            if not row:
+                return None
+            update_time = int(row["last_updated_timestamp"])
+
+            return datetime.utcfromtimestamp(update_time)