add licensed feature usage API

src/core/server/mocks.ts

@@ -18,7 +18,7 @@
  */
 import { of } from 'rxjs';
 import { duration } from 'moment';
-import { PluginInitializerContext, CoreSetup, CoreStart } from '.';
+import { PluginInitializerContext, CoreSetup, CoreStart, StartServicesAccessor } from '.';
 import { CspConfig } from './csp';
 import { loggingServiceMock } from './logging/logging_service.mock';
 import { elasticsearchServiceMock } from './elasticsearch/elasticsearch_service.mock';
@@ -99,7 +99,9 @@ function pluginInitializerContextMock<T>(config: T = {} as T) {
   return mock;
 }
 
-type CoreSetupMockType = MockedKeys<CoreSetup> & jest.Mocked<Pick<CoreSetup, 'getStartServices'>>;
+type CoreSetupMockType = MockedKeys<CoreSetup> & {
+  getStartServices: jest.MockedFunction<StartServicesAccessor<any, any>>;
+};
 
 function createCoreSetupMock({
   pluginStartDeps = {},

x-pack/plugins/licensing/server/mocks.ts

@@ -4,15 +4,17 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 import { BehaviorSubject } from 'rxjs';
-import { LicensingPluginSetup } from './types';
+import { LicensingPluginSetup, LicensingPluginStart } from './types';
 import { licenseMock } from '../common/licensing.mock';
+import { featureUsageMock } from './services/feature_usage_service.mock';
 
-const createSetupMock = () => {
+const createSetupMock = (): jest.Mocked<LicensingPluginSetup> => {
   const license = licenseMock.createLicense();
-  const mock: jest.Mocked<LicensingPluginSetup> = {
+  const mock = {
     license$: new BehaviorSubject(license),
     refresh: jest.fn(),
     createLicensePoller: jest.fn(),
+    featureUsage: featureUsageMock.createSetup(),
   };
   mock.refresh.mockResolvedValue(license);
   mock.createLicensePoller.mockReturnValue({
@@ -23,7 +25,16 @@ const createSetupMock = () => {
   return mock;
 };
 
+const createStartMock = (): jest.Mocked<LicensingPluginStart> => {
+  const mock = {
+    featureUsage: featureUsageMock.createStart(),
+  };
+
+  return mock;
+};
+
 export const licensingMock = {
   createSetup: createSetupMock,
+  createStart: createStartMock,
   ...licenseMock,
 };

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

@@ -20,12 +20,13 @@ import {
 } from 'src/core/server';
 
 import { ILicense, PublicLicense, PublicFeatures } from '../common/types';
-import { LicensingPluginSetup } from './types';
+import { LicensingPluginSetup, LicensingPluginStart } from './types';
 import { License } from '../common/license';
 import { createLicenseUpdate } from '../common/license_update';
 
 import { ElasticsearchError, RawLicense, RawFeatures } from './types';
 import { registerRoutes } from './routes';
+import { FeatureUsageService } from './services';
 
 import { LicenseConfigType } from './licensing_config';
 import { createRouteHandlerContext } from './licensing_route_handler_context';
@@ -77,18 +78,19 @@ function sign({
  * A plugin for fetching, refreshing, and receiving information about the license for the
  * current Kibana instance.
  */
-export class LicensingPlugin implements Plugin<LicensingPluginSetup> {
+export class LicensingPlugin implements Plugin<LicensingPluginSetup, LicensingPluginStart, {}, {}> {
   private stop$ = new Subject();
   private readonly logger: Logger;
   private readonly config$: Observable<LicenseConfigType>;
   private loggingSubscription?: Subscription;
+  private featureUsage = new FeatureUsageService();
 
   constructor(private readonly context: PluginInitializerContext) {
     this.logger = this.context.logger.get();
     this.config$ = this.context.config.create<LicenseConfigType>();
   }
 
-  public async setup(core: CoreSetup) {
+  public async setup(core: CoreSetup<{}, LicensingPluginStart>) {
     this.logger.debug('Setting up Licensing plugin');
     const config = await this.config$.pipe(take(1)).toPromise();
     const pollingFrequency = config.api_polling_frequency;
@@ -101,13 +103,14 @@ export class LicensingPlugin implements Plugin<LicensingPluginSetup> {
 
     core.http.registerRouteHandlerContext('licensing', createRouteHandlerContext(license$));
 
-    registerRoutes(core.http.createRouter());
+    registerRoutes(core.http.createRouter(), core.getStartServices);
     core.http.registerOnPreResponse(createOnPreResponseHandler(refresh, license$));
 
     return {
       refresh,
       license$,
       createLicensePoller: this.createLicensePoller.bind(this),
+      featureUsage: this.featureUsage.setup(),
     };
   }
 
@@ -186,7 +189,11 @@ export class LicensingPlugin implements Plugin<LicensingPluginSetup> {
     return error.message;
   }
 
-  public async start(core: CoreStart) {}
+  public async start(core: CoreStart) {
+    return {
+      featureUsage: this.featureUsage.start(),
+    };
+  }
 
   public stop() {
     this.stop$.next();

x-pack/plugins/licensing/server/routes/feature_usage.ts

@@ -0,0 +1,30 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+import { IRouter, StartServicesAccessor } from 'src/core/server';
+import { LicensingPluginStart } from '../types';
+
+export function registerFeatureUsageRoute(
+  router: IRouter,
+  getStartServices: StartServicesAccessor<{}, LicensingPluginStart>
+) {
+  router.get(
+    { path: '/api/licensing/feature_usage', validate: false },
+    async (context, request, response) => {
+      const [, , { featureUsage }] = await getStartServices();
+      return response.ok({
+        body: [...featureUsage.getLastUsages().entries()].reduce(
+          (res, [featureName, lastUsage]) => {
+            return {
+              ...res,
+              [featureName]: new Date(lastUsage).toISOString(),
+            };
+          },
+          {}
+        ),
+      });
+    }
+  );
+}

x-pack/plugins/licensing/server/routes/index.ts

@@ -3,9 +3,16 @@
  * or more contributor license agreements. Licensed under the Elastic License;
  * you may not use this file except in compliance with the Elastic License.
  */
-import { IRouter } from 'src/core/server';
+
+import { IRouter, StartServicesAccessor } from 'src/core/server';
+import { LicensingPluginStart } from '../types';
 import { registerInfoRoute } from './info';
+import { registerFeatureUsageRoute } from './feature_usage';
 
-export function registerRoutes(router: IRouter) {
+export function registerRoutes(
+  router: IRouter,
+  getStartServices: StartServicesAccessor<{}, LicensingPluginStart>
+) {
   registerInfoRoute(router);
+  registerFeatureUsageRoute(router, getStartServices);
 }

x-pack/plugins/licensing/server/services/feature_usage_service.mock.ts

@@ -0,0 +1,44 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+import {
+  FeatureUsageService,
+  FeatureUsageServiceSetup,
+  FeatureUsageServiceStart,
+} from './feature_usage_service';
+
+const createSetupMock = (): jest.Mocked<FeatureUsageServiceSetup> => {
+  const mock = {
+    register: jest.fn(),
+  };
+
+  return mock;
+};
+
+const createStartMock = (): jest.Mocked<FeatureUsageServiceStart> => {
+  const mock = {
+    notifyUsage: jest.fn(),
+    getLastUsages: jest.fn(),
+    clear: jest.fn(),
+  };
+
+  return mock;
+};
+
+const createServiceMock = (): jest.Mocked<PublicMethodsOf<FeatureUsageService>> => {
+  const mock = {
+    setup: jest.fn(() => createSetupMock()),
+    start: jest.fn(() => createStartMock()),
+  };
+
+  return mock;
+};
+
+export const featureUsageMock = {
+  create: createServiceMock,
+  createSetup: createSetupMock,
+  createStart: createStartMock,
+};

x-pack/plugins/licensing/server/services/feature_usage_service.test.ts

@@ -0,0 +1,124 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+import { FeatureUsageService } from './feature_usage_service';
+
+describe('FeatureUsageService', () => {
+  let service: FeatureUsageService;
+
+  beforeEach(() => {
+    service = new FeatureUsageService();
+  });
+
+  afterEach(() => {
+    jest.restoreAllMocks();
+  });
+
+  const toObj = (map: ReadonlyMap<string, any>): Record<string, any> =>
+    Object.fromEntries(map.entries());
+
+  describe('#setup', () => {
+    describe('#register', () => {
+      it('throws when registering the same feature twice', () => {
+        const setup = service.setup();
+        setup.register('foo');
+        expect(() => {
+          setup.register('foo');
+        }).toThrowErrorMatchingInlineSnapshot(`"Feature 'foo' has already been registered."`);
+      });
+    });
+  });
+
+  describe('#start', () => {
+    describe('#notifyUsage', () => {
+      it('allows to notify a feature usage', () => {
+        const setup = service.setup();
+        setup.register('feature');
+        const start = service.start();
+        start.notifyUsage('feature', 127001);
+
+        expect(start.getLastUsages().get('feature')).toBe(127001);
+      });
+
+      it('uses the current time when `usedAt` is unspecified', () => {
+        jest.spyOn(Date, 'now').mockReturnValue(42);
+
+        const setup = service.setup();
+        setup.register('feature');
+        const start = service.start();
+        start.notifyUsage('feature');
+
+        expect(start.getLastUsages().get('feature')).toBe(42);
+      });
+
+      it('throws when notifying for an unregistered feature', () => {
+        service.setup();
+        const start = service.start();
+        expect(() => {
+          start.notifyUsage('unregistered');
+        }).toThrowErrorMatchingInlineSnapshot(`"Feature 'unregistered' is not registered."`);
+      });
+    });
+
+    describe('#getLastUsages', () => {
+      it('returns the last usage for all used features', () => {
+        const setup = service.setup();
+        setup.register('featureA');
+        setup.register('featureB');
+        const start = service.start();
+        start.notifyUsage('featureA', 127001);
+        start.notifyUsage('featureB', 6666);
+
+        expect(toObj(start.getLastUsages())).toEqual({
+          featureA: 127001,
+          featureB: 6666,
+        });
+      });
+
+      it('returns the last usage even after notifying for an older usage', () => {
+        const setup = service.setup();
+        setup.register('featureA');
+        const start = service.start();
+        start.notifyUsage('featureA', 1000);
+        start.notifyUsage('featureA', 500);
+
+        expect(toObj(start.getLastUsages())).toEqual({
+          featureA: 1000,
+        });
+      });
+
+      it('does not return entries for unused registered features', () => {
+        const setup = service.setup();
+        setup.register('featureA');
+        setup.register('featureB');
+        const start = service.start();
+        start.notifyUsage('featureA', 127001);
+
+        expect(toObj(start.getLastUsages())).toEqual({
+          featureA: 127001,
+        });
+      });
+    });
+
+    describe('#clear', () => {
+      it('clears the whole last usages map', () => {
+        const setup = service.setup();
+        setup.register('featureA');
+        setup.register('featureB');
+
+        const start = service.start();
+        start.notifyUsage('featureA');
+        start.notifyUsage('featureB');
+
+        expect([...start.getLastUsages().keys()]).toEqual(['featureA', 'featureB']);
+
+        start.clear();
+
+        expect([...start.getLastUsages().keys()]).toEqual([]);
+      });
+    });
+  });
+});