[Feature Flags] Client-side bootstrapping (#224258)

src/core/packages/feature-flags/browser-internal/src/feature_flags_service.test.ts

@@ -249,6 +249,7 @@ describe('FeatureFlagsService Browser', () => {
           'myPlugin.myOverriddenFlag': true,
           myDestructuredObjPlugin: { myOverriddenFlag: true },
         },
+        initialFeatureFlags: {},
       });
       featureFlagsService.setup({ injectedMetadata });
       startContract = await featureFlagsService.start();

src/core/packages/feature-flags/browser-internal/src/feature_flags_service.ts

@@ -24,7 +24,7 @@ import { get } from 'lodash';
 
 /**
  * setup method dependencies
- * @private
+ * @internal
  */
 export interface FeatureFlagsSetupDeps {
   /**
@@ -35,7 +35,7 @@ export interface FeatureFlagsSetupDeps {
 
 /**
  * The browser-side Feature Flags Service
- * @private
+ * @internal
  */
 export class FeatureFlagsService {
   private readonly featureFlagsClient: Client;
@@ -64,6 +64,7 @@ export class FeatureFlagsService {
       this.overrides = featureFlagsInjectedMetadata.overrides;
     }
     return {
+      getInitialFeatureFlags: () => featureFlagsInjectedMetadata?.initialFeatureFlags ?? {},
       setProvider: (provider) => {
         if (this.isProviderReadyPromise) {
           throw new Error('A provider has already been set. This API cannot be called twice.');
@@ -159,7 +160,7 @@ export class FeatureFlagsService {
 
   /**
    * Waits for the provider initialization with a timeout to avoid holding the page load for too long
-   * @private
+   * @internal
    */
   private async waitForProviderInitialization() {
     // Adding a timeout here to avoid hanging the start for too long if the provider is unresponsive
@@ -185,7 +186,7 @@ export class FeatureFlagsService {
    * @param evaluationFn The actual evaluation API
    * @param flagName The name of the flag to evaluate
    * @param fallbackValue The fallback value
-   * @private
+   * @internal
    */
   private evaluateFlag<T extends string | boolean | number>(
     evaluationFn: (flagName: string, fallbackValue: T) => T,
@@ -206,7 +207,7 @@ export class FeatureFlagsService {
   /**
    * Formats the provided context to fulfill the expected multi-context structure.
    * @param contextToAppend The {@link EvaluationContext} to append.
-   * @private
+   * @internal
    */
   private async appendContext(contextToAppend: EvaluationContext): Promise<void> {
     // If no kind provided, default to the project|deployment level.

src/core/packages/feature-flags/browser-mocks/index.ts

@@ -14,6 +14,7 @@ import { of } from 'rxjs';
 
 const createFeatureFlagsSetup = (): jest.Mocked<FeatureFlagsSetup> => {
   return {
+    getInitialFeatureFlags: jest.fn().mockImplementation(() => ({})),
     setProvider: jest.fn(),
     appendContext: jest.fn().mockImplementation(Promise.resolve),
   };

src/core/packages/feature-flags/browser/src/types.ts

@@ -87,6 +87,12 @@ export type SingleContextEvaluationContext = OpenFeatureEvaluationContext & {
  * @public
  */
 export interface FeatureFlagsSetup {
+  /**
+   * Used for bootstrapping the browser-side client with a seed of the feature flags for faster load-times.
+   * @remarks It shouldn't be used to evaluate the feature flags because it won't report usage.
+   */
+  getInitialFeatureFlags: () => Record<string, unknown>;
+
   /**
    * Registers an OpenFeature provider to talk to the
    * 3rd-party service that manages the Feature Flags.

src/core/packages/feature-flags/server-internal/src/feature_flags_config.ts

@@ -12,7 +12,7 @@ import { schema } from '@kbn/config-schema';
 
 /**
  * The definition of the validation config schema
- * @private
+ * @internal
  */
 const configSchema = schema.object({
   overrides: schema.maybe(schema.recordOf(schema.string(), schema.any())),
@@ -20,7 +20,7 @@ const configSchema = schema.object({
 
 /**
  * Type definition of the Feature Flags configuration
- * @private
+ * @internal
  */
 export interface FeatureFlagsConfig {
   overrides?: Record<string, unknown>;
@@ -28,7 +28,7 @@ export interface FeatureFlagsConfig {
 
 /**
  * Config descriptor for the feature flags service
- * @private
+ * @internal
  */
 export const featureFlagsConfig: ServiceConfigDescriptor<FeatureFlagsConfig> = {
   /**

src/core/packages/feature-flags/server-internal/src/feature_flags_service.test.ts

@@ -320,4 +320,19 @@ describe('FeatureFlagsService Server', () => {
       'myDestructuredObjPlugin.myOverriddenFlag': true,
     });
   });
+
+  describe('bootstrapping helpers', () => {
+    test('return empty initial feature flags if no getter registered', async () => {
+      const { getInitialFeatureFlags } = featureFlagsService.setup();
+      await expect(getInitialFeatureFlags()).resolves.toEqual({});
+    });
+
+    test('calls the getter when registered', async () => {
+      const { setInitialFeatureFlagsGetter, getInitialFeatureFlags } = featureFlagsService.setup();
+      const mockGetter = jest.fn().mockResolvedValue({ myFlag: true });
+      setInitialFeatureFlagsGetter(mockGetter);
+      await expect(getInitialFeatureFlags()).resolves.toEqual({ myFlag: true });
+      expect(mockGetter).toHaveBeenCalledTimes(1);
+    });
+  });
 });

src/core/packages/feature-flags/server-internal/src/feature_flags_service.ts

@@ -26,24 +26,30 @@ import {
 import deepMerge from 'deepmerge';
 import { filter, switchMap, startWith, Subject, BehaviorSubject, pairwise, takeUntil } from 'rxjs';
 import { get } from 'lodash';
+import type { InitialFeatureFlagsGetter } from '@kbn/core-feature-flags-server/src/contracts';
 import { createOpenFeatureLogger } from './create_open_feature_logger';
 import { setProviderWithRetries } from './set_provider_with_retries';
 import { type FeatureFlagsConfig, featureFlagsConfig } from './feature_flags_config';
 
 /**
  * Core-internal contract for the setup lifecycle step.
- * @private
+ * @internal
  */
 export interface InternalFeatureFlagsSetup extends FeatureFlagsSetup {
   /**
    * Used by the rendering service to share the overrides with the service on the browser side.
    */
   getOverrides: () => Record<string, unknown>;
+  /**
+   * Required to bootstrap the browser-side OpenFeature client with a seed of the feature flags for faster load-times
+   * and to work-around air-gapped environments.
+   */
+  getInitialFeatureFlags: () => Promise<Record<string, unknown>>;
 }
 
 /**
  * The server-side Feature Flags Service
- * @private
+ * @internal
  */
 export class FeatureFlagsService {
   private readonly featureFlagsClient: Client;
@@ -51,6 +57,7 @@ export class FeatureFlagsService {
   private readonly stop$ = new Subject<void>();
   private readonly overrides$ = new BehaviorSubject<Record<string, unknown>>({});
   private context: MultiContextEvaluationContext = { kind: 'multi' };
+  private initialFeatureFlagsGetter: InitialFeatureFlagsGetter = async () => ({});
 
   /**
    * The core service's constructor
@@ -77,6 +84,10 @@ export class FeatureFlagsService {
 
     return {
       getOverrides: () => this.overrides$.value,
+      getInitialFeatureFlags: () => this.initialFeatureFlagsGetter(),
+      setInitialFeatureFlagsGetter: (getter: InitialFeatureFlagsGetter) => {
+        this.initialFeatureFlagsGetter = getter;
+      },
       setProvider: (provider) => {
         if (OpenFeature.providerMetadata !== NOOP_PROVIDER.metadata) {
           throw new Error('A provider has already been set. This API cannot be called twice.');
@@ -175,7 +186,7 @@ export class FeatureFlagsService {
    * @param evaluationFn The actual evaluation API
    * @param flagName The name of the flag to evaluate
    * @param fallbackValue The fallback value
-   * @private
+   * @internal
    */
   private async evaluateFlag<T extends string | boolean | number>(
     evaluationFn: (flagName: string, fallbackValue: T) => Promise<T>,
@@ -196,7 +207,7 @@ export class FeatureFlagsService {
   /**
    * Formats the provided context to fulfill the expected multi-context structure.
    * @param contextToAppend The {@link EvaluationContext} to append.
-   * @private
+   * @internal
    */
   private appendContext(contextToAppend: EvaluationContext): void {
     // If no kind provided, default to the project|deployment level.

src/core/packages/feature-flags/server-mocks/index.ts

@@ -23,11 +23,13 @@ const createFeatureFlagsInternalSetup = (): jest.Mocked<InternalFeatureFlagsSetu
   return {
     ...createFeatureFlagsSetup(),
     getOverrides: jest.fn().mockReturnValue({}),
+    getInitialFeatureFlags: jest.fn().mockImplementation(async () => ({})),
   };
 };
 
 const createFeatureFlagsSetup = (): jest.Mocked<FeatureFlagsSetup> => {
   return {
+    setInitialFeatureFlagsGetter: jest.fn(),
     setProvider: jest.fn(),
     appendContext: jest.fn(),
   };

src/core/packages/feature-flags/server/index.ts

@@ -13,6 +13,7 @@ export type {
   SingleContextEvaluationContext,
   FeatureFlagsSetup,
   FeatureFlagsStart,
+  InitialFeatureFlagsGetter,
 } from './src/contracts';
 export type { FeatureFlagDefinition, FeatureFlagDefinitions } from './src/feature_flag_definition';
 export type { FeatureFlagsRequestHandlerContext } from './src/request_handler_context';

src/core/packages/feature-flags/server/src/contracts.ts

@@ -82,6 +82,12 @@ export type SingleContextEvaluationContext = OpenFeatureEvaluationContext & {
   kind?: 'organization' | 'kibana';
 };
 
+/**
+ * Getter function type to retrieve the initial feature flags.
+ * @internal
+ */
+export type InitialFeatureFlagsGetter = () => Promise<Record<string, unknown>>;
+
 /**
  * Setup contract of the Feature Flags Service
  * @public
@@ -101,6 +107,15 @@ export interface FeatureFlagsSetup {
    * @public
    */
   appendContext(contextToAppend: EvaluationContext): void;
+
+  /**
+   * Registers a getter function that will be used to retrieve the initial feature flags to be injected into the
+   * browser for faster bootstrapping.
+   * @param getter A function that returns all the feature flags and their values for this context.
+   * Ideally, using the underlying API shouldn't track them as actual evaluations.
+   * @internal
+   */
+  setInitialFeatureFlagsGetter(getter: InitialFeatureFlagsGetter): void;
 }
 
 /**

src/core/packages/injected-metadata/browser-internal/src/injected_metadata_service.test.ts

@@ -170,12 +170,20 @@ describe('setup.getFeatureFlags()', () => {
           overrides: {
             'my-overridden-flag': 1234,
           },
+          initialFeatureFlags: {
+            'my-initial-flag': true,
+          },
         },
       },
     } as unknown as InjectedMetadataParams);
 
     const contract = injectedMetadata.setup();
-    expect(contract.getFeatureFlags()).toStrictEqual({ overrides: { 'my-overridden-flag': 1234 } });
+    expect(contract.getFeatureFlags()).toStrictEqual({
+      overrides: { 'my-overridden-flag': 1234 },
+      initialFeatureFlags: {
+        'my-initial-flag': true,
+      },
+    });
   });
 
   it('returns empty injectedMetadata.featureFlags', () => {

src/core/packages/injected-metadata/browser-internal/src/types.ts

@@ -61,6 +61,7 @@ export interface InternalInjectedMetadataSetup {
   getFeatureFlags: () =>
     | {
         overrides: Record<string, unknown>;
+        initialFeatureFlags: Record<string, unknown>;
       }
     | undefined;
 }

src/core/packages/injected-metadata/common-internal/src/types.ts

@@ -66,6 +66,7 @@ export interface InjectedMetadata {
   };
   featureFlags?: {
     overrides: Record<string, unknown>;
+    initialFeatureFlags: Record<string, unknown>;
   };
   anonymousStatusPage: boolean;
   i18n: {

src/core/packages/plugins/server-internal/src/plugin_context.ts

@@ -220,6 +220,7 @@ export function createPluginSetupContext<TPlugin, TPluginDependencies>({
       getAsLabels: deps.executionContext.getAsLabels,
     },
     featureFlags: {
+      setInitialFeatureFlagsGetter: deps.featureFlags.setInitialFeatureFlagsGetter,
       setProvider: deps.featureFlags.setProvider,
       appendContext: deps.featureFlags.appendContext,
     },

src/core/packages/rendering/server-internal/src/__snapshots__/rendering_service.test.ts.snap

@@ -40,6 +40,7 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {},
   },
   "i18n": Object {
@@ -126,6 +127,7 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {},
   },
   "i18n": Object {
@@ -208,6 +210,7 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {},
   },
   "i18n": Object {
@@ -294,6 +297,7 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {},
   },
   "i18n": Object {
@@ -376,6 +380,7 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {},
   },
   "i18n": Object {
@@ -458,6 +463,7 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {},
   },
   "i18n": Object {
@@ -544,6 +550,7 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {},
   },
   "i18n": Object {
@@ -626,6 +633,7 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {},
   },
   "i18n": Object {
@@ -708,6 +716,90 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
+    "overrides": Object {},
+  },
+  "i18n": Object {
+    "translationsUrl": "/mock-server-basepath/translations/MOCK_HASH/en.json",
+  },
+  "legacyMetadata": Object {
+    "globalUiSettings": Object {
+      "defaults": Object {},
+      "user": Object {},
+    },
+    "uiSettings": Object {
+      "defaults": Object {
+        "registered": Object {
+          "name": "title",
+        },
+      },
+      "user": Object {},
+    },
+  },
+  "logging": Any<Object>,
+  "publicBaseUrl": "http://myhost.com/mock-server-basepath",
+  "serverBasePath": "/mock-server-basepath",
+  "theme": Object {
+    "darkMode": "theme:darkMode",
+    "name": "borealis",
+    "stylesheetPaths": Object {
+      "dark": Array [
+        "/style-1.css",
+        "/style-2.css",
+      ],
+      "default": Array [
+        "/style-1.css",
+        "/style-2.css",
+      ],
+    },
+    "version": "v8",
+  },
+  "uiPlugins": Array [],
+  "version": Any<String>,
+}
+`;
+
+exports[`RenderingService preboot() render() renders initial feature flags 1`] = `
+Object {
+  "anonymousStatusPage": false,
+  "apmConfig": Object {
+    "stubApmConfig": true,
+  },
+  "assetsHrefBase": "http://foo.bar:1773",
+  "basePath": "/mock-server-basepath",
+  "branch": Any<String>,
+  "buildNumber": Any<Number>,
+  "clusterInfo": Object {},
+  "csp": Object {
+    "warnLegacyBrowsers": true,
+  },
+  "customBranding": Object {},
+  "env": Object {
+    "mode": Object {
+      "dev": Any<Boolean>,
+      "name": Any<String>,
+      "prod": Any<Boolean>,
+    },
+    "packageInfo": Object {
+      "branch": Any<String>,
+      "buildDate": "2023-05-15T23:12:09.000Z",
+      "buildFlavor": Any<String>,
+      "buildNum": Any<Number>,
+      "buildSha": Any<String>,
+      "buildShaShort": "XXXXXX",
+      "dist": Any<Boolean>,
+      "version": Any<String>,
+    },
+  },
+  "externalUrl": Object {
+    "policy": Array [
+      Object {
+        "allow": true,
+      },
+    ],
+  },
+  "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {},
   },
   "i18n": Object {
@@ -795,6 +887,7 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {},
   },
   "i18n": Object {
@@ -881,6 +974,9 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {
+      "my-initial-flag": 1234,
+    },
     "overrides": Object {},
   },
   "i18n": Object {
@@ -968,6 +1064,7 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {},
   },
   "i18n": Object {
@@ -1059,6 +1156,7 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {},
   },
   "i18n": Object {
@@ -1141,6 +1239,7 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {},
   },
   "i18n": Object {
@@ -1228,6 +1327,7 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {},
   },
   "i18n": Object {
@@ -1319,6 +1419,7 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {},
   },
   "i18n": Object {
@@ -1406,6 +1507,7 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {},
   },
   "i18n": Object {
@@ -1493,6 +1595,7 @@ Object {
     ],
   },
   "featureFlags": Object {
+    "initialFeatureFlags": Object {},
     "overrides": Object {
       "my-overridden-flag": 1234,
     },
@@ -1536,3 +1639,93 @@ Object {
   "version": Any<String>,
 }
 `;
+
+exports[`RenderingService setup() render() renders initial feature flags 1`] = `
+Object {
+  "anonymousStatusPage": false,
+  "apmConfig": Object {
+    "stubApmConfig": true,
+  },
+  "assetsHrefBase": "/mock-server-basepath",
+  "basePath": "/mock-server-basepath",
+  "branch": Any<String>,
+  "buildNumber": Any<Number>,
+  "clusterInfo": Object {
+    "cluster_build_flavor": "default",
+    "cluster_name": "cluster-name",
+    "cluster_uuid": "cluster-uuid",
+    "cluster_version": "8.0.0",
+  },
+  "csp": Object {
+    "warnLegacyBrowsers": true,
+  },
+  "customBranding": Object {},
+  "env": Object {
+    "mode": Object {
+      "dev": Any<Boolean>,
+      "name": Any<String>,
+      "prod": Any<Boolean>,
+    },
+    "packageInfo": Object {
+      "branch": Any<String>,
+      "buildDate": "2023-05-15T23:12:09.000Z",
+      "buildFlavor": Any<String>,
+      "buildNum": Any<Number>,
+      "buildSha": Any<String>,
+      "buildShaShort": "XXXXXX",
+      "dist": Any<Boolean>,
+      "version": Any<String>,
+    },
+  },
+  "externalUrl": Object {
+    "policy": Array [
+      Object {
+        "allow": true,
+      },
+    ],
+  },
+  "featureFlags": Object {
+    "initialFeatureFlags": Object {
+      "my-initial-flag": 1234,
+    },
+    "overrides": Object {},
+  },
+  "i18n": Object {
+    "translationsUrl": "/mock-server-basepath/translations/MOCK_HASH/en.json",
+  },
+  "legacyMetadata": Object {
+    "globalUiSettings": Object {
+      "defaults": Object {},
+      "user": Object {},
+    },
+    "uiSettings": Object {
+      "defaults": Object {
+        "registered": Object {
+          "name": "title",
+        },
+      },
+      "user": Object {},
+    },
+  },
+  "logging": Any<Object>,
+  "publicBaseUrl": "http://myhost.com/mock-server-basepath",
+  "serverBasePath": "/mock-server-basepath",
+  "theme": Object {
+    "darkMode": "theme:darkMode",
+    "name": "borealis",
+    "stylesheetPaths": Object {
+      "dark": Array [
+        "/style-1.css",
+        "/style-2.css",
+      ],
+      "default": Array [
+        "/style-1.css",
+        "/style-2.css",
+      ],
+    },
+    "version": "v8",
+  },
+  "uiPlugins": Array [],
+  "version": Any<String>,
+}
+`;

src/core/packages/rendering/server-internal/src/rendering_service.test.ts

@@ -265,6 +265,19 @@ function renderTestCases(
       expect(data).toMatchSnapshot(INJECTED_METADATA);
     });
 
+    it('renders initial feature flags', async () => {
+      mockRenderingSetupDeps.featureFlags.getInitialFeatureFlags.mockResolvedValueOnce({
+        'my-initial-flag': 1234,
+      });
+      const [render] = await getRender();
+      const content = await render(createKibanaRequest(), uiSettings, {
+        isAnonymousPage: false,
+      });
+      const dom = load(content);
+      const data = JSON.parse(dom('kbn-injected-metadata').attr('data') ?? '""');
+      expect(data).toMatchSnapshot(INJECTED_METADATA);
+    });
+
     it('renders "core" with logging config injected', async () => {
       const loggingConfig = {
         root: {

src/core/packages/rendering/server-internal/src/rendering_service.tsx

@@ -298,6 +298,7 @@ export class RenderingService {
         env,
         featureFlags: {
           overrides: featureFlags?.getOverrides() || {},
+          initialFeatureFlags: (await featureFlags?.getInitialFeatureFlags()) || {},
         },
         clusterInfo,
         apmConfig,

x-pack/platform/plugins/private/cloud_integrations/cloud_experiments/public/plugin.test.mocks.ts

@@ -0,0 +1,13 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+export const LaunchDarklyClientProviderMocked = jest.fn();
+jest.doMock('@openfeature/launchdarkly-client-provider', () => {
+  return {
+    LaunchDarklyClientProvider: LaunchDarklyClientProviderMocked,
+  };
+});

x-pack/platform/plugins/private/cloud_integrations/cloud_experiments/public/plugin.test.ts

@@ -9,6 +9,7 @@ import { duration } from 'moment';
 import { coreMock } from '@kbn/core/public/mocks';
 import { cloudMock } from '@kbn/cloud-plugin/public/mocks';
 import { dataViewPluginMocks } from '@kbn/data-views-plugin/public/mocks';
+import { LaunchDarklyClientProviderMocked } from './plugin.test.mocks';
 import { CloudExperimentsPlugin } from './plugin';
 import { MetadataService } from '../common/metadata_service';
 
@@ -69,6 +70,32 @@ describe('Cloud Experiments public plugin', () => {
         })
       ).toBeUndefined();
     });
+
+    test('leverages the injected initial feature flags when creating the new client', () => {
+      const coreSetup = coreMock.createSetup();
+      coreSetup.featureFlags.getInitialFeatureFlags.mockReturnValue({
+        'my-initial-flag': true,
+      });
+      plugin.setup(coreSetup, { cloud: cloudMock.createSetup() });
+      expect(LaunchDarklyClientProviderMocked).toHaveBeenCalledWith(
+        '1234',
+        expect.objectContaining({
+          bootstrap: { 'my-initial-flag': true },
+        })
+      );
+    });
+
+    test('use undefined bootstrap when creating the new client and no provided initial feature flags', () => {
+      const coreSetup = coreMock.createSetup();
+      coreSetup.featureFlags.getInitialFeatureFlags.mockReturnValue({});
+      plugin.setup(coreSetup, { cloud: cloudMock.createSetup() });
+      expect(LaunchDarklyClientProviderMocked).toHaveBeenCalledWith(
+        '1234',
+        expect.objectContaining({
+          bootstrap: undefined,
+        })
+      );
+    });
   });
 
   describe('start', () => {

x-pack/platform/plugins/private/cloud_integrations/cloud_experiments/public/plugin.ts

@@ -73,7 +73,8 @@ export class CloudExperimentsPlugin
       logger: this.logger,
     });
 
-    const launchDarklyOpenFeatureProvider = this.createOpenFeatureProvider();
+    const initialFeatureFlags = core.featureFlags.getInitialFeatureFlags();
+    const launchDarklyOpenFeatureProvider = this.createOpenFeatureProvider(initialFeatureFlags);
     if (launchDarklyOpenFeatureProvider) {
       core.featureFlags.setProvider(launchDarklyOpenFeatureProvider);
     }
@@ -101,13 +102,15 @@ export class CloudExperimentsPlugin
    * Sets up the OpenFeature LaunchDarkly provider
    * @private
    */
-  private createOpenFeatureProvider() {
+  private createOpenFeatureProvider(initialFeatureFlags: Record<string, unknown>) {
     const { launch_darkly: ldConfig } = this.initializerContext.config.get<{
       launch_darkly?: LaunchDarklyClientConfig;
     }>();
 
     if (!ldConfig) return;
 
+    const bootstrap = Object.keys(initialFeatureFlags).length > 0 ? initialFeatureFlags : undefined;
+
     return new LaunchDarklyClientProvider(ldConfig.client_id, {
       // logger: this.logger.get('launch-darkly'),
       // Using basicLogger for now because we can't limit the level for now if we're using core's logger.
@@ -120,6 +123,7 @@ export class CloudExperimentsPlugin
             ? this.initializerContext.env.packageInfo.buildSha
             : this.initializerContext.env.packageInfo.version,
       },
+      bootstrap,
     });
   }
 }

x-pack/platform/plugins/private/cloud_integrations/cloud_experiments/server/plugin.test.ts

@@ -102,6 +102,15 @@ describe('Cloud Experiments server plugin', () => {
         },
       });
     });
+
+    test('registers the initial feature flags getter to enable bootstrapping', async () => {
+      const coreSetupMock = coreMock.createSetup();
+      plugin.setup(coreSetupMock, {
+        cloud: cloudMock.createSetup(),
+        usageCollection: usageCollectionPluginMock.createSetupContract(),
+      });
+      expect(coreSetupMock.featureFlags.setInitialFeatureFlagsGetter).toHaveBeenCalledTimes(1);
+    });
   });
 
   describe('start', () => {

x-pack/platform/plugins/private/cloud_integrations/cloud_experiments/server/plugin.ts

@@ -20,7 +20,7 @@ import type { UsageCollectionSetup } from '@kbn/usage-collection-plugin/server';
 import type { CloudSetup } from '@kbn/cloud-plugin/server';
 import type { DataViewsServerPluginStart } from '@kbn/data-views-plugin/server/types';
 import { initializeMetadata, MetadataService } from '../common/metadata_service';
-import { registerUsageCollector } from './usage';
+import { getAllFlags, registerUsageCollector } from './usage';
 import type { CloudExperimentsConfigType } from './config';
 
 interface CloudExperimentsPluginSetupDeps {
@@ -79,6 +79,12 @@ export class CloudExperimentsPlugin
     const launchDarklyOpenFeatureProvider = this.createOpenFeatureProvider();
     if (launchDarklyOpenFeatureProvider) {
       core.featureFlags.setProvider(launchDarklyOpenFeatureProvider);
+      core.featureFlags.setInitialFeatureFlagsGetter(async () => {
+        const launchDarklyClient = launchDarklyOpenFeatureProvider.getClient();
+        const context = OpenFeature.getContext();
+        const { flags } = await getAllFlags(launchDarklyClient, context);
+        return flags;
+      });
     }
 
     registerUsageCollector(deps.usageCollection, () => ({

x-pack/platform/plugins/private/cloud_integrations/cloud_experiments/server/usage/index.ts

@@ -5,4 +5,4 @@
  * 2.0.
  */
 
-export { registerUsageCollector } from './register_usage_collector';
+export { registerUsageCollector, getAllFlags } from './register_usage_collector';

x-pack/platform/plugins/private/cloud_integrations/cloud_experiments/server/usage/register_usage_collector.ts

@@ -60,7 +60,7 @@ export function registerUsageCollector(
   );
 }
 
-async function getAllFlags(
+export async function getAllFlags(
   launchDarklyClient: LDClient,
   currentContext: EvaluationContext
 ): Promise<Usage> {