handling different versions of Postgres of unit

Author: BalabaDmitri

src/charm.py

@@ -469,7 +469,7 @@ def _on_peer_relation_changed(self, event: HookEvent):
             event.defer()
             return
 
-        if not self.validate_database_version(self._patroni.get_postgresql_version()):
+        if not self._validate_database_version(self._patroni.get_postgresql_version()):
             self.unit.status = BlockedStatus(DIFFERENT_VERSIONS_PSQL_BLOCKING_MESSAGE)
             return
 
@@ -1584,7 +1584,8 @@ def client_relations(self) -> List[Relation]:
                 relations.append(relation)
         return relations
 
-    def validate_database_version(self, version: str) -> bool:
+    def _validate_database_version(self, version: str) -> bool:
+        """Checking that only one version of Postgres is used"""
         peer_db_version = self.app_peer_data.get("database-version")
 
         if self.unit.is_leader() and peer_db_version is None: