Add saved objects service status api

Signed-off-by: Bandini Bhopi <bandinib@amazon.com>

src/core/server/legacy/legacy_service.ts

@@ -276,6 +276,9 @@ export class LegacyService implements CoreService {
         registerType: setupDeps.core.savedObjects.registerType,
         getImportExportObjectLimit: setupDeps.core.savedObjects.getImportExportObjectLimit,
         setRepositoryFactoryProvider: setupDeps.core.savedObjects.setRepositoryFactoryProvider,
+        setStatus: () => {
+          throw new Error(`core.savedObjects.setStatus is unsupported in legacy`);
+        },
       },
       status: {
         isStatusPageAnonymous: setupDeps.core.status.isStatusPageAnonymous,

src/core/server/plugins/plugin_context.ts

@@ -205,6 +205,7 @@ export function createPluginSetupContext<TPlugin, TPluginDependencies>(
       registerType: deps.savedObjects.registerType,
       getImportExportObjectLimit: deps.savedObjects.getImportExportObjectLimit,
       setRepositoryFactoryProvider: deps.savedObjects.setRepositoryFactoryProvider,
+      setStatus: deps.savedObjects.setStatus,
     },
     status: {
       core$: deps.status.core$,

src/core/server/saved_objects/saved_objects_service.mock.ts

@@ -80,6 +80,7 @@ const createSetupContractMock = () => {
     registerType: jest.fn(),
     getImportExportObjectLimit: jest.fn(),
     setRepositoryFactoryProvider: jest.fn(),
+    setStatus: jest.fn(),
   };
 
   setupContract.getImportExportObjectLimit.mockReturnValue(100);

src/core/server/saved_objects/saved_objects_service.test.ts

@@ -34,7 +34,8 @@ import {
   clientProviderInstanceMock,
   typeRegistryInstanceMock,
 } from './saved_objects_service.test.mocks';
-import { BehaviorSubject } from 'rxjs';
+import { BehaviorSubject, of } from 'rxjs';
+import { first } from 'rxjs/operators';
 import { ByteSizeValue } from '@osd/config-schema';
 import { errors as opensearchErrors } from '@opensearch-project/opensearch';
 
@@ -50,6 +51,7 @@ import { SavedObjectsClientFactoryProvider } from './service/lib';
 import { NodesVersionCompatibility } from '../opensearch/version_check/ensure_opensearch_version';
 import { SavedObjectsRepository } from './service/lib/repository';
 import { SavedObjectRepositoryFactoryProvider } from './service/lib/scoped_client_provider';
+import { ServiceStatusLevels } from '../status';
 
 jest.mock('./service/lib/repository');
 
@@ -191,6 +193,31 @@ describe('SavedObjectsService', () => {
         );
       });
     });
+
+    describe('#setStatus', () => {
+      it('throws error if custom status is already set', async () => {
+        const coreContext = createCoreContext();
+        const soService = new SavedObjectsService(coreContext);
+        const setup = await soService.setup(createSetupDeps());
+
+        const customStatus1$ = of({
+          level: ServiceStatusLevels.available,
+          summary: 'Saved Object Service is using external storage and it is up',
+        });
+        const customStatus2$ = of({
+          level: ServiceStatusLevels.unavailable,
+          summary: 'Saved Object Service is not connected to external storage and it is down',
+        });
+
+        setup.setStatus(customStatus1$);
+
+        expect(() => {
+          setup.setStatus(customStatus2$);
+        }).toThrowErrorMatchingInlineSnapshot(
+          `"custom saved object service status is already set, and can only be set once"`
+        );
+      });
+    });
   });
 
   describe('#start()', () => {
@@ -312,6 +339,15 @@ describe('SavedObjectsService', () => {
       }).toThrowErrorMatchingInlineSnapshot(
         '"cannot call `setRepositoryFactoryProvider` after service startup."'
       );
+
+      const customStatus$ = of({
+        level: ServiceStatusLevels.available,
+        summary: 'Saved Object Service is using external storage and it is up',
+      });
+
+      expect(() => {
+        setup.setStatus(customStatus$);
+      }).toThrowErrorMatchingInlineSnapshot('"cannot call `setStatus` after service startup."');
     });
 
     describe('#getTypeRegistry', () => {
@@ -430,5 +466,39 @@ describe('SavedObjectsService', () => {
         expect(SavedObjectsRepository.createRepository as jest.Mocked<any>).toHaveBeenCalled();
       });
     });
+
+    describe('#savedObjectServiceStatus', () => {
+      it('Saved objects service status should be custom when set using setStatus', async () => {
+        const coreContext = createCoreContext({});
+        const soService = new SavedObjectsService(coreContext);
+        const coreSetup = createSetupDeps();
+        const setup = await soService.setup(coreSetup);
+
+        const customStatus$ = of({
+          level: ServiceStatusLevels.available,
+          summary: 'Saved Object Service is using external storage and it is up',
+        });
+        setup.setStatus(customStatus$);
+        const coreStart = createStartDeps();
+        await soService.start(coreStart);
+        expect(await setup.status$.pipe(first()).toPromise()).toMatchObject({
+          level: ServiceStatusLevels.available,
+          summary: 'Saved Object Service is using external storage and it is up',
+        });
+      });
+
+      it('Saved objects service should be default when custom status is not set', async () => {
+        const coreContext = createCoreContext({});
+        const soService = new SavedObjectsService(coreContext);
+        const coreSetup = createSetupDeps();
+        const setup = await soService.setup(coreSetup);
+        const coreStart = createStartDeps();
+        await soService.start(coreStart);
+        expect(await setup.status$.pipe(first()).toPromise()).toMatchObject({
+          level: ServiceStatusLevels.available,
+          summary: 'SavedObjects service has completed migrations and is available',
+        });
+      });
+    });
   });
 });

src/core/server/saved_objects/saved_objects_service.ts

@@ -28,8 +28,10 @@
  * under the License.
  */
 
-import { Subject, Observable } from 'rxjs';
-import { first, filter, take, switchMap } from 'rxjs/operators';
+import { Subject, Observable, BehaviorSubject } from 'rxjs';
+import { first, filter, take, switchMap, map, distinctUntilChanged } from 'rxjs/operators';
+import { isDeepStrictEqual } from 'util';
+
 import { CoreService } from '../../types';
 import {
   SavedObjectsClient,
@@ -62,7 +64,7 @@ import { Logger } from '../logging';
 import { SavedObjectTypeRegistry, ISavedObjectTypeRegistry } from './saved_objects_type_registry';
 import { SavedObjectsSerializer } from './serialization';
 import { registerRoutes } from './routes';
-import { ServiceStatus } from '../status';
+import { ServiceStatus, ServiceStatusLevels } from '../status';
 import { calculateStatus$ } from './status';
 import { createMigrationOpenSearchClient } from './migrations/core/';
 /**
@@ -175,6 +177,12 @@ export interface SavedObjectsServiceSetup {
   setRepositoryFactoryProvider: (
     respositoryFactoryProvider: SavedObjectRepositoryFactoryProvider
   ) => void;
+
+  /**
+   * Allows a plugin to specify a custom status dependent on its own criteria.
+   * Completely overrides the default status.
+   */
+  setStatus(status$: Observable<ServiceStatus<SavedObjectStatusMeta>>): void;
 }
 
 /**
@@ -301,6 +309,11 @@ export class SavedObjectsService
   private started = false;
 
   private respositoryFactoryProvider?: SavedObjectRepositoryFactoryProvider;
+  private savedObjectServiceCustomStatus$?: Observable<ServiceStatus<SavedObjectStatusMeta>>;
+  private savedObjectServiceStatus$ = new BehaviorSubject<ServiceStatus<SavedObjectStatusMeta>>({
+    level: ServiceStatusLevels.unavailable,
+    summary: `waiting`,
+  });
 
   constructor(private readonly coreContext: CoreContext) {
     this.logger = coreContext.logger.get('savedobjects-service');
@@ -329,10 +342,7 @@ export class SavedObjectsService
     });
 
     return {
-      status$: calculateStatus$(
-        this.migrator$.pipe(switchMap((migrator) => migrator.getStatus$())),
-        setupDeps.opensearch.status$
-      ),
+      status$: this.savedObjectServiceStatus$.asObservable(),
       setClientFactoryProvider: (provider) => {
         if (this.started) {
           throw new Error('cannot call `setClientFactoryProvider` after service startup.');
@@ -368,6 +378,17 @@ export class SavedObjectsService
         }
         this.respositoryFactoryProvider = repositoryProvider;
       },
+      setStatus: (status$) => {
+        if (this.started) {
+          throw new Error('cannot call `setStatus` after service startup.');
+        }
+        if (this.savedObjectServiceCustomStatus$) {
+          throw new Error(
+            'custom saved object service status is already set, and can only be set once'
+          );
+        }
+        this.savedObjectServiceCustomStatus$ = status$;
+      },
     };
   }
 
@@ -381,6 +402,29 @@ export class SavedObjectsService
 
     this.logger.debug('Starting SavedObjects service');
 
+    if (this.savedObjectServiceCustomStatus$) {
+      this.savedObjectServiceCustomStatus$
+        .pipe(
+          map((savedObjectServiceCustomStatus) => {
+            return savedObjectServiceCustomStatus;
+          }),
+          distinctUntilChanged<ServiceStatus<SavedObjectStatusMeta>>(isDeepStrictEqual)
+        )
+        .subscribe((value) => this.savedObjectServiceStatus$.next(value));
+    } else {
+      calculateStatus$(
+        this.migrator$.pipe(switchMap((migrator) => migrator.getStatus$())),
+        this.setupDeps.opensearch.status$
+      )
+        .pipe(
+          map((defaultstatus) => {
+            return defaultstatus;
+          }),
+          distinctUntilChanged<ServiceStatus<SavedObjectStatusMeta>>(isDeepStrictEqual)
+        )
+        .subscribe((value) => this.savedObjectServiceStatus$.next(value));
+    }
+
     const opensearchDashboardsConfig = await this.coreContext.configService
       .atPath<OpenSearchDashboardsConfigType>('opensearchDashboards')
       .pipe(first())
@@ -492,7 +536,9 @@ export class SavedObjectsService
     };
   }
 
-  public async stop() {}
+  public async stop() {
+    this.savedObjectServiceStatus$.unsubscribe();
+  }
 
   private createMigrator(
     opensearchDashboardsConfig: OpenSearchDashboardsConfigType,