[DPE-7640] Migrate from Management API to nodetool (#6)

* Get rid of Management API.

* Get rid of read_file & write_file functions from Workload.

Author: Zvirovyi

src/charm.py

@@ -30,7 +30,7 @@ def __init__(self, *args):
 
         state = ApplicationState(self)
         workload = CassandraWorkload()
-        cluster_manager = ClusterManager()
+        cluster_manager = ClusterManager(workload=workload)
         config_manager = ConfigManager(workload=workload)
 
         self.framework.observe(self.on.collect_unit_status, self._on_collect_unit_status)

src/common/management_client.py

@@ -70,25 +70,6 @@ def alive(self) -> bool:
         """
         pass
 
-    @abstractmethod
-    def write_file(self, content: str, file: str) -> None:
-        """Write content to a file.
-
-        Args:
-            content (str): Content to write to the file.
-            file (str): Path to the file.
-        """
-        pass
-
-    @abstractmethod
-    def read_file(self, file: str) -> str:
-        """Read content from file.
-
-        Args:
-            file (str): Path to the file.
-        """
-        pass
-
     @abstractmethod
     def stop(self) -> None:
         """Stop the workload service."""

src/core/workload.py

@@ -106,9 +106,8 @@ def _on_collect_unit_status(self, event: CollectStatusEvent) -> None:
         if self.state.unit.workload_state == UnitWorkloadState.STARTING.value:
             event.add_status(Status.STARTING.value)
 
-        if (
-            self.state.unit.workload_state == UnitWorkloadState.ACTIVE.value
-            and not self.cluster_manager.is_healthy
+        if self.state.unit.workload_state == UnitWorkloadState.ACTIVE.value and (
+            not self.workload.alive() or not self.cluster_manager.is_healthy
         ):
             event.add_status(Status.STARTING.value)
 

src/events/cassandra.py

@@ -7,25 +7,29 @@
 import logging
 import socket
 
-from common.management_client import ManagementClient
+from common.exceptions import ExecError
+from core.workload import WorkloadBase
 
 logger = logging.getLogger(__name__)
 
+_NODETOOL = "charmed-cassandra.nodetool"
+
 
 class ClusterManager:
     """Manage cluster members, quorum and authorization."""
 
-    def __init__(self):
-        self.management_client = ManagementClient()
+    def __init__(self, workload: WorkloadBase):
+        self._workload = workload
+        pass
 
     @property
     def is_healthy(self) -> bool:
-        """Perform cassandra helth and readiness checks and return True if healthy.
-
-        Returns:
-            bool: True if the cluster or node is healthy.
-        """
-        return self.management_client.is_healthy()
+        """TODO."""
+        try:
+            stdout, _ = self._workload.exec([_NODETOOL, "info"])
+            return "Native Transport active: true" in stdout
+        except ExecError:
+            return False
 
     def network_address(self) -> tuple[str, str]:
         """TODO."""

src/managers/cluster.py

@@ -21,7 +21,7 @@
 
 SNAP_NAME = "charmed-cassandra"
 SNAP_REVISION = "8"
-SNAP_SERVICE = "mgmt-server"
+SNAP_SERVICE = "daemon"
 
 logger = logging.getLogger(__name__)
 
@@ -66,19 +66,6 @@ def alive(self) -> bool:
         except KeyError:
             return False
 
-    @override
-    def write_file(self, content: str, file: str) -> None:
-        path = self.root / file
-        path.parent.mkdir(exist_ok=True, parents=True)
-        path.write_text(content)
-
-    @override
-    def read_file(self, file: str) -> str:
-        path = self.root / file
-        if not path.exists():
-            raise FileNotFoundError(f"File '{file}' does not exist.")
-        return path.read_text()
-
     @override
     def stop(self) -> None:
         self._cassandra_snap.stop(services=[SNAP_SERVICE])