Reuse class PostgreSQL on each self.postgresql.* call (#1030)

* Reuse class PostgreSQL on each postgresql call

* Visualise Patroni /cluster status calls to catch 'None' issue

* Re-init class PostgreSQL if we got primary_host=None

It should be explored further and isolate primary_host=None.

Author: taurus-forever

src/charm.py

@@ -251,6 +251,7 @@ class PostgresqlOperatorCharm(TypedCharmBase[CharmConfig]):
 
     config_type = CharmConfig
     on = ClusterTopologyChangeCharmEvents()
+    _postgresql: PostgreSQL | None = None
 
     def __init__(self, *args):
         super().__init__(*args)
@@ -605,14 +606,20 @@ def is_unit_stopped(self) -> bool:
     @property
     def postgresql(self) -> PostgreSQL:
         """Returns an instance of the object used to interact with the database."""
-        return PostgreSQL(
-            primary_host=self.primary_endpoint,
-            current_host=self._unit_ip,
-            user=USER,
-            password=self.get_secret(APP_SCOPE, f"{USER}-password"),
-            database=DATABASE_DEFAULT_NAME,
-            system_users=SYSTEM_USERS,
-        )
+        password = str(self.get_secret(APP_SCOPE, f"{USER}-password"))
+        if self._postgresql is None or self._postgresql.primary_host is None:
+            logger.debug("Init class PostgreSQL")
+            self._postgresql = PostgreSQL(
+                primary_host=self.primary_endpoint,
+                current_host=self._unit_ip,
+                user=USER,
+                password=password,
+                database=DATABASE_DEFAULT_NAME,
+                system_users=SYSTEM_USERS,
+            )
+        else:
+            self._postgresql.password = password
+        return self._postgresql
 
     @property
     def primary_endpoint(self) -> str | None:

src/cluster.py

@@ -260,6 +260,7 @@ def cluster_status(self, alternative_endpoints: list | None = None) -> list[Clus
         if response := self.parallel_patroni_get_request(
             f"/{PATRONI_CLUSTER_STATUS_ENDPOINT}", alternative_endpoints
         ):
+            logger.debug("Patroni cluster members: %s", response["members"])
             return response["members"]
         raise RetryError(last_attempt=Exception("Unable to reach any units"))