Make stop method of the taskManager plugin async (#191218)

towards: https://github.com/elastic/kibana/issues/189306

This PR fixes the `Deleting current node has failed.`errors mentioned in
the above issue.

x-pack/plugins/task_manager/server/kibana_discovery_service/kibana_discovery_service.test.ts

@@ -193,19 +193,5 @@ describe('KibanaDiscoveryService', () => {
         'Removed this node from the Kibana Discovery Service'
       );
     });
-
-    it('logs an error when failed', async () => {
-      savedObjectsRepository.delete.mockRejectedValue(new Error('bar'));
-
-      const kibanaDiscoveryService = new KibanaDiscoveryService({
-        savedObjectsRepository,
-        logger,
-        currentNode,
-      });
-
-      await kibanaDiscoveryService.deleteCurrentNode();
-
-      expect(logger.error).toHaveBeenCalledWith('Deleting current node has failed. error: bar');
-    });
   });
 });

x-pack/plugins/task_manager/server/kibana_discovery_service/kibana_discovery_service.ts

@@ -100,11 +100,7 @@ export class KibanaDiscoveryService {
   }
 
   public async deleteCurrentNode() {
-    try {
-      await this.savedObjectsRepository.delete(BACKGROUND_TASK_NODE_SO_NAME, this.currentNode);
-      this.logger.info('Removed this node from the Kibana Discovery Service');
-    } catch (e) {
-      this.logger.error(`Deleting current node has failed. error: ${e.message}`);
-    }
+    await this.savedObjectsRepository.delete(BACKGROUND_TASK_NODE_SO_NAME, this.currentNode);
+    this.logger.info('Removed this node from the Kibana Discovery Service');
   }
 }

x-pack/plugins/task_manager/server/plugin.test.ts

@@ -6,6 +6,8 @@
  */
 
 import { TaskManagerPlugin, getElasticsearchAndSOAvailability } from './plugin';
+import { KibanaDiscoveryService } from './kibana_discovery_service';
+
 import { coreMock } from '@kbn/core/server/mocks';
 import { TaskManagerConfig } from './config';
 import { Subject } from 'rxjs';
@@ -37,6 +39,9 @@ jest.mock('./ephemeral_task_lifecycle', () => {
   };
 });
 
+const deleteCurrentNodeSpy = jest.spyOn(KibanaDiscoveryService.prototype, 'deleteCurrentNode');
+const discoveryIsStarted = jest.spyOn(KibanaDiscoveryService.prototype, 'isStarted');
+
 const coreStart = coreMock.createStart();
 const pluginInitializerContextParams = {
   max_attempts: 9,
@@ -176,6 +181,25 @@ describe('TaskManagerPlugin', () => {
     });
   });
 
+  describe('stop', () => {
+    test('should remove the current from discovery service', async () => {
+      const pluginInitializerContext = coreMock.createPluginInitializerContext<TaskManagerConfig>(
+        pluginInitializerContextParams
+      );
+      pluginInitializerContext.node.roles.backgroundTasks = true;
+      const taskManagerPlugin = new TaskManagerPlugin(pluginInitializerContext);
+      taskManagerPlugin.setup(coreMock.createSetup(), { usageCollection: undefined });
+      taskManagerPlugin.start(coreStart, {
+        cloud: cloudMock.createStart(),
+      });
+
+      discoveryIsStarted.mockReturnValueOnce(true);
+      await taskManagerPlugin.stop();
+
+      expect(deleteCurrentNodeSpy).toHaveBeenCalledTimes(1);
+    });
+  });
+
   describe('getElasticsearchAndSOAvailability', () => {
     test('returns true when both services are available', async () => {
       const core$ = new Subject<CoreStatus>();

x-pack/plugins/task_manager/server/plugin.ts

@@ -395,9 +395,13 @@ export class TaskManagerPlugin
     };
   }
 
-  public stop() {
+  public async stop() {
     if (this.kibanaDiscoveryService?.isStarted()) {
-      this.kibanaDiscoveryService.deleteCurrentNode().catch(() => {});
+      try {
+        await this.kibanaDiscoveryService.deleteCurrentNode();
+      } catch (e) {
+        this.logger.error(`Deleting current node has failed. error: ${e.message}`);
+      }
     }
   }
 }