[DPE-5481] Ensure that uninitialized variable not referenced in _is_cluster_blocked helper (#507)

* Ensure that uninitialized variable not referenced in _is_cluster_blocked helper

* Simplify member_state existence in _is_cluster_blocked

* Update outdate tracing charm lib

Author: shayancanonical

lib/charms/tempo_k8s/v2/tracing.py

@@ -107,7 +107,7 @@ def __init__(self, *args):
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 9
+LIBPATCH = 10
 
 PYDEPS = ["pydantic"]
 
@@ -902,7 +902,16 @@ def _get_endpoint(
     def get_endpoint(
         self, protocol: ReceiverProtocol, relation: Optional[Relation] = None
     ) -> Optional[str]:
-        """Receiver endpoint for the given protocol."""
+        """Receiver endpoint for the given protocol.
+
+        It could happen that this function gets called before the provider publishes the endpoints.
+        In such a scenario, if a non-leader unit calls this function, a permission denied exception will be raised due to
+        restricted access. To prevent this, this function needs to be guarded by the `is_ready` check.
+
+        Raises:
+        ProtocolNotRequestedError:
+            If the charm unit is the leader unit and attempts to obtain an endpoint for a protocol it did not request.
+        """
         endpoint = self._get_endpoint(relation or self._relation, protocol=protocol)
         if not endpoint:
             requested_protocols = set()

src/charm.py

@@ -815,20 +815,19 @@ def _is_cluster_blocked(self) -> bool:
         # We need to query member state from the server since member state would
         # be 'offline' if pod rescheduled during cluster creation, however
         # member-state in the unit peer databag will be 'waiting'
-        member_state_exists = True
         try:
             member_state, _ = self._mysql.get_member_state()
         except MySQLUnableToGetMemberStateError:
             logger.error("Error getting member state while checking if cluster is blocked")
             self.unit.status = MaintenanceStatus("Unable to get member state")
             return True
         except MySQLNoMemberStateError:
-            member_state_exists = False
+            member_state = None
 
-        if not member_state_exists or member_state == "restarting":
+        if not member_state or member_state == "restarting":
             # avoid changing status while tls is being set up or charm is being initialized
             logger.info("Unit is waiting or restarting")
-            logger.debug(f"{member_state_exists=}, {member_state=}")
+            logger.debug(f"{member_state=}")
             return True
 
         # avoid changing status while async replication is setting up