Remove plugin status message before cluster ready

This PR proposes to move the cluster ready check that originally happens
within `plugin_manager.run()` to be executed at `_on_config_changed`. If
the cluster is ready, then we proceed to inform the user we will start the
plugin configuration.

It also updates the message to inform we are checking the plugin configs
instead of applying anything.

lib/charms/opensearch/v0/constants_charm.py

@@ -74,7 +74,7 @@
 WaitingForOtherUnitServiceOps = "Waiting for other units to complete the ops on their service."
 NewIndexRequested = "new index {index} requested"
 RestoreInProgress = "Restore in progress..."
-PluginConfigStart = "Plugin configuration started."
+PluginConfigCheck = "Plugin configuration check."
 BackupSetupStart = "Backup setup started."
 BackupConfigureStart = "Configuring backup service..."
 BackupInDisabling = "Disabling backup service..."

lib/charms/opensearch/v0/opensearch_base_charm.py

@@ -21,7 +21,7 @@
     COSUser,
     PeerRelationName,
     PluginConfigChangeError,
-    PluginConfigStart,
+    PluginConfigCheck,
     RequestUnitServiceOps,
     SecurityIndexInitProgress,
     ServiceIsStopping,
@@ -484,18 +484,23 @@ def _on_config_changed(self, event: ConfigChangedEvent):
             return
 
         try:
-            self.status.set(MaintenanceStatus(PluginConfigStart))
+            if not self.plugin_manager.check_plugin_manager_ready():
+                raise OpenSearchNotFullyReadyError()
+            self.status.set(MaintenanceStatus(PluginConfigCheck))
             if self.plugin_manager.run():
                 self.on[self.service_manager.name].acquire_lock.emit(
                     callback_override="_restart_opensearch"
                 )
-            self.status.clear(PluginConfigStart)
+            self.status.clear(PluginConfigCheck)
         except (OpenSearchNotFullyReadyError, OpenSearchPluginError) as e:
             if isinstance(e, OpenSearchNotFullyReadyError):
                 logger.warning("Plugin management: cluster not ready yet at config changed")
             else:
                 self.status.set(BlockedStatus(PluginConfigChangeError))
             event.defer()
+            # Decided to defer the event. We can clean up the status and reset it once the
+            # config-changed is called again.
+            self.status.clear(PluginConfigCheck)
             return
         self.status.clear(PluginConfigChangeError)
 

lib/charms/opensearch/v0/opensearch_plugin_manager.py

@@ -16,10 +16,7 @@
 from typing import Any, Dict, List, Optional, Tuple
 
 from charms.opensearch.v0.helper_cluster import ClusterTopology
-from charms.opensearch.v0.opensearch_exceptions import (
-    OpenSearchCmdError,
-    OpenSearchNotFullyReadyError,
-)
+from charms.opensearch.v0.opensearch_exceptions import OpenSearchCmdError
 from charms.opensearch.v0.opensearch_health import HealthColors
 from charms.opensearch.v0.opensearch_keystore import OpenSearchKeystore
 from charms.opensearch.v0.opensearch_plugins import (
@@ -154,9 +151,6 @@ def run(self) -> bool:
 
         This method should be called at config-changed event. Returns if needed restart.
         """
-        if not self.check_plugin_manager_ready():
-            raise OpenSearchNotFullyReadyError()
-
         err_msgs = []
         restart_needed = False
         for plugin in self.plugins:

tests/unit/lib/test_plugins.py

@@ -209,6 +209,7 @@ def test_check_plugin_called_on_config_changed(self, mock_version, deployment_de
         self.plugin_manager.run = MagicMock(return_value=False)
         self.charm.opensearch_config.update_host_if_needed = MagicMock(return_value=False)
         self.charm.opensearch.is_started = MagicMock(return_value=True)
+        self.plugin_manager.check_plugin_manager_ready = MagicMock(return_value=True)
         self.harness.update_config({})
         self.plugin_manager.run.assert_called()