[data.search.SearchSource] Remove legacy ES client APIs. (#75943) (#76676)

package.json

@@ -362,7 +362,6 @@
     "dedent": "^0.7.0",
     "deepmerge": "^4.2.2",
     "delete-empty": "^2.0.0",
-    "elasticsearch-browser": "^16.7.0",
     "enzyme": "^3.11.0",
     "enzyme-adapter-react-16": "^1.15.2",
     "enzyme-adapter-utils": "^1.13.0",

packages/kbn-optimizer/src/worker/webpack.config.ts

@@ -77,7 +77,6 @@ export function getWebpackConfig(bundle: Bundle, bundleRefs: BundleRefs, worker:
       // or which have require() statements that should be ignored because the file is
       // already bundled with all its necessary depedencies
       noParse: [
-        /[\/\\]node_modules[\/\\]elasticsearch-browser[\/\\]/,
         /[\/\\]node_modules[\/\\]lodash[\/\\]index\.js$/,
         /[\/\\]node_modules[\/\\]vega[\/\\]build[\/\\]vega\.js$/,
       ],

packages/kbn-ui-shared-deps/entry.js

@@ -54,6 +54,3 @@ export const ElasticEuiChartsTheme = require('@elastic/eui/dist/eui_charts_theme
 
 import * as Theme from './theme.ts';
 export { Theme };
-
-// massive deps that we should really get rid of or reduce in size substantially
-export const ElasticsearchBrowser = require('elasticsearch-browser/elasticsearch.js');

packages/kbn-ui-shared-deps/index.js

@@ -62,12 +62,5 @@ exports.externals = {
   '@elastic/eui/dist/eui_charts_theme': '__kbnSharedDeps__.ElasticEuiChartsTheme',
   '@elastic/eui/dist/eui_theme_light.json': '__kbnSharedDeps__.Theme.euiLightVars',
   '@elastic/eui/dist/eui_theme_dark.json': '__kbnSharedDeps__.Theme.euiDarkVars',
-
-  /**
-   * massive deps that we should really get rid of or reduce in size substantially
-   */
-  elasticsearch: '__kbnSharedDeps__.ElasticsearchBrowser',
-  'elasticsearch-browser': '__kbnSharedDeps__.ElasticsearchBrowser',
-  'elasticsearch-browser/elasticsearch': '__kbnSharedDeps__.ElasticsearchBrowser',
 };
 exports.publicPathLoader = require.resolve('./public_path_loader');

packages/kbn-ui-shared-deps/package.json

@@ -19,7 +19,6 @@
     "compression-webpack-plugin": "^4.0.0",
     "core-js": "^3.2.1",
     "custom-event-polyfill": "^0.3.0",
-    "elasticsearch-browser": "^16.7.0",
     "jquery": "^3.5.0",
     "mini-css-extract-plugin": "0.8.0",
     "moment": "^2.24.0",

src/plugins/data/public/plugin.ts

@@ -19,13 +19,7 @@
 
 import './index.scss';
 
-import {
-  PluginInitializerContext,
-  CoreSetup,
-  CoreStart,
-  Plugin,
-  PackageInfo,
-} from 'src/core/public';
+import { PluginInitializerContext, CoreSetup, CoreStart, Plugin } from 'src/core/public';
 import { ConfigSchema } from '../config';
 import { Storage, IStorageWrapper, createStartServicesGetter } from '../../kibana_utils/public';
 import {
@@ -101,7 +95,6 @@ export class DataPublicPlugin
   private readonly fieldFormatsService: FieldFormatsService;
   private readonly queryService: QueryService;
   private readonly storage: IStorageWrapper;
-  private readonly packageInfo: PackageInfo;
 
   constructor(initializerContext: PluginInitializerContext<ConfigSchema>) {
     this.searchService = new SearchService();
@@ -109,7 +102,6 @@ export class DataPublicPlugin
     this.fieldFormatsService = new FieldFormatsService();
     this.autocomplete = new AutocompleteService(initializerContext);
     this.storage = new Storage(window.localStorage);
-    this.packageInfo = initializerContext.env.packageInfo;
   }
 
   public setup(
@@ -146,7 +138,6 @@ export class DataPublicPlugin
 
     const searchService = this.searchService.setup(core, {
       usageCollection,
-      packageInfo: this.packageInfo,
       expressions,
     });
 

src/plugins/data/public/public.api.md

@@ -28,6 +28,7 @@ import { ExpressionAstFunction } from 'src/plugins/expressions/common';
 import { ExpressionsSetup } from 'src/plugins/expressions/public';
 import { History } from 'history';
 import { Href } from 'history';
+import { HttpStart } from 'src/core/public';
 import { IconType } from '@elastic/eui';
 import { InjectedIntl } from '@kbn/i18n/react';
 import { ISearchOptions as ISearchOptions_2 } from 'src/plugins/data/public';

src/plugins/data/public/search/fetch/types.ts

@@ -17,8 +17,9 @@
  * under the License.
  */
 
+import { HttpStart } from 'src/core/public';
+import { BehaviorSubject } from 'rxjs';
 import { GetConfigFn } from '../../../common';
-import { ISearchStartLegacy } from '../types';
 
 /**
  * @internal
@@ -30,9 +31,9 @@ import { ISearchStartLegacy } from '../types';
 export type SearchRequest = Record<string, any>;
 
 export interface FetchHandlers {
-  legacySearchService: ISearchStartLegacy;
   config: { get: GetConfigFn };
-  esShardTimeout: number;
+  http: HttpStart;
+  loadingCount$: BehaviorSubject<number>;
 }
 
 export interface SearchError {

src/plugins/data/public/search/legacy/call_client.test.ts

@@ -17,11 +17,13 @@
  * under the License.
  */
 
+import { coreMock } from '../../../../../core/public/mocks';
 import { callClient } from './call_client';
 import { SearchStrategySearchParams } from './types';
 import { defaultSearchStrategy } from './default_search_strategy';
 import { FetchHandlers } from '../fetch';
 import { handleResponse } from '../fetch/handle_response';
+import { BehaviorSubject } from 'rxjs';
 
 const mockAbortFn = jest.fn();
 jest.mock('../fetch/handle_response', () => ({
@@ -54,7 +56,13 @@ describe('callClient', () => {
 
   test('Passes the additional arguments it is given to the search strategy', () => {
     const searchRequests = [{ _searchStrategyId: 0 }];
-    const args = { legacySearchService: {}, config: {}, esShardTimeout: 0 } as FetchHandlers;
+    const args = {
+      http: coreMock.createStart().http,
+      legacySearchService: {},
+      config: { get: jest.fn() },
+      esShardTimeout: 0,
+      loadingCount$: new BehaviorSubject(0),
+    } as FetchHandlers;
 
     callClient(searchRequests, [], args);
 

src/plugins/data/public/search/legacy/default_search_strategy.test.ts

@@ -17,44 +17,26 @@
  * under the License.
  */
 
-import { IUiSettingsClient } from 'kibana/public';
+import { HttpStart } from 'src/core/public';
+import { coreMock } from '../../../../../core/public/mocks';
 import { defaultSearchStrategy } from './default_search_strategy';
-import { searchServiceMock } from '../mocks';
 import { SearchStrategySearchParams } from './types';
-import { UI_SETTINGS } from '../../../common';
+import { BehaviorSubject } from 'rxjs';
 
 const { search } = defaultSearchStrategy;
 
-function getConfigStub(config: any = {}) {
-  return {
-    get: (key) => config[key],
-  } as IUiSettingsClient;
-}
-
-const msearchMockResponse: any = Promise.resolve([]);
-msearchMockResponse.abort = jest.fn();
-const msearchMock = jest.fn().mockReturnValue(msearchMockResponse);
-
-const searchMockResponse: any = Promise.resolve([]);
-searchMockResponse.abort = jest.fn();
-const searchMock = jest.fn().mockReturnValue(searchMockResponse);
+const msearchMock = jest.fn().mockResolvedValue({ body: { responses: [] } });
 
 describe('defaultSearchStrategy', function () {
   describe('search', function () {
-    let searchArgs: MockedKeys<Omit<SearchStrategySearchParams, 'config'>>;
-    let es: any;
+    let searchArgs: MockedKeys<SearchStrategySearchParams>;
+    let http: jest.Mocked<HttpStart>;
 
     beforeEach(() => {
-      msearchMockResponse.abort.mockClear();
       msearchMock.mockClear();
 
-      searchMockResponse.abort.mockClear();
-      searchMock.mockClear();
-
-      const searchService = searchServiceMock.createStartContract();
-      searchService.aggs.calculateAutoTimeExpression = jest.fn().mockReturnValue('1d');
-      searchService.__LEGACY.esClient.search = searchMock;
-      searchService.__LEGACY.esClient.msearch = msearchMock;
+      http = coreMock.createStart().http;
+      http.post.mockResolvedValue(msearchMock);
 
       searchArgs = {
         searchRequests: [
@@ -62,49 +44,27 @@ describe('defaultSearchStrategy', function () {
             index: { title: 'foo' },
           },
         ],
-        esShardTimeout: 0,
-        legacySearchService: searchService.__LEGACY,
+        http,
+        config: {
+          get: jest.fn(),
+        },
+        loadingCount$: new BehaviorSubject(0) as any,
       };
-
-      es = searchArgs.legacySearchService.esClient;
     });
 
-    test('does not send max_concurrent_shard_requests by default', async () => {
-      const config = getConfigStub({ [UI_SETTINGS.COURIER_BATCH_SEARCHES]: true });
-      await search({ ...searchArgs, config });
-      expect(es.msearch.mock.calls[0][0].max_concurrent_shard_requests).toBe(undefined);
-    });
-
-    test('allows configuration of max_concurrent_shard_requests', async () => {
-      const config = getConfigStub({
-        [UI_SETTINGS.COURIER_BATCH_SEARCHES]: true,
-        [UI_SETTINGS.COURIER_MAX_CONCURRENT_SHARD_REQUESTS]: 42,
-      });
-      await search({ ...searchArgs, config });
-      expect(es.msearch.mock.calls[0][0].max_concurrent_shard_requests).toBe(42);
-    });
-
-    test('should set rest_total_hits_as_int to true on a request', async () => {
-      const config = getConfigStub({ [UI_SETTINGS.COURIER_BATCH_SEARCHES]: true });
-      await search({ ...searchArgs, config });
-      expect(es.msearch.mock.calls[0][0]).toHaveProperty('rest_total_hits_as_int', true);
-    });
-
-    test('should set ignore_throttled=false when including frozen indices', async () => {
-      const config = getConfigStub({
-        [UI_SETTINGS.COURIER_BATCH_SEARCHES]: true,
-        [UI_SETTINGS.SEARCH_INCLUDE_FROZEN]: true,
-      });
-      await search({ ...searchArgs, config });
-      expect(es.msearch.mock.calls[0][0]).toHaveProperty('ignore_throttled', false);
-    });
-
-    test('should properly call abort with msearch', () => {
-      const config = getConfigStub({
-        [UI_SETTINGS.COURIER_BATCH_SEARCHES]: true,
-      });
-      search({ ...searchArgs, config }).abort();
-      expect(msearchMockResponse.abort).toHaveBeenCalled();
+    test('calls http.post with the correct arguments', async () => {
+      await search({ ...searchArgs });
+      expect(http.post.mock.calls).toMatchInlineSnapshot(`
+        Array [
+          Array [
+            "/internal/_msearch",
+            Object {
+              "body": "{\\"searches\\":[{\\"header\\":{\\"index\\":\\"foo\\"}}]}",
+              "signal": AbortSignal {},
+            },
+          ],
+        ]
+      `);
     });
   });
 });

src/plugins/data/public/search/legacy/default_search_strategy.ts

@@ -17,8 +17,7 @@
  * under the License.
  */
 
-import { getPreference, getTimeout } from '../fetch';
-import { getMSearchParams } from './get_msearch_params';
+import { getPreference } from '../fetch';
 import { SearchStrategyProvider, SearchStrategySearchParams } from './types';
 
 // @deprecated
@@ -30,34 +29,45 @@ export const defaultSearchStrategy: SearchStrategyProvider = {
   },
 };
 
-function msearch({
-  searchRequests,
-  legacySearchService,
-  config,
-  esShardTimeout,
-}: SearchStrategySearchParams) {
-  const es = legacySearchService.esClient;
-  const inlineRequests = searchRequests.map(({ index, body, search_type: searchType }) => {
-    const inlineHeader = {
-      index: index.title || index,
-      search_type: searchType,
-      ignore_unavailable: true,
-      preference: getPreference(config.get),
+function msearch({ searchRequests, config, http, loadingCount$ }: SearchStrategySearchParams) {
+  const requests = searchRequests.map(({ index, body }) => {
+    return {
+      header: {
+        index: index.title || index,
+        preference: getPreference(config.get),
+      },
+      body,
     };
-    const inlineBody = {
-      ...body,
-      timeout: getTimeout(esShardTimeout),
-    };
-    return `${JSON.stringify(inlineHeader)}\n${JSON.stringify(inlineBody)}`;
   });
 
-  const searching = es.msearch({
-    ...getMSearchParams(config.get),
-    body: `${inlineRequests.join('\n')}\n`,
-  });
+  const abortController = new AbortController();
+  let resolved = false;
+
+  // Start LoadingIndicator
+  loadingCount$.next(loadingCount$.getValue() + 1);
+
+  const cleanup = () => {
+    if (!resolved) {
+      resolved = true;
+      // Decrement loading counter & cleanup BehaviorSubject
+      loadingCount$.next(loadingCount$.getValue() - 1);
+      loadingCount$.complete();
+    }
+  };
+
+  const searching = http
+    .post('/internal/_msearch', {
+      body: JSON.stringify({ searches: requests }),
+      signal: abortController.signal,
+    })
+    .then(({ body }) => body?.responses)
+    .finally(() => cleanup());
 
   return {
-    searching: searching.then(({ responses }: any) => responses),
-    abort: searching.abort,
+    abort: () => {
+      abortController.abort();
+      cleanup();
+    },
+    searching,
   };
 }

src/plugins/data/public/search/legacy/es_client/get_es_client.ts

@@ -1,98 +0,0 @@
-/*
- * Licensed to Elasticsearch B.V. under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch B.V. licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-// @ts-ignore
-import { default as es } from 'elasticsearch-browser/elasticsearch';
-import { CoreStart, PackageInfo } from 'kibana/public';
-import { BehaviorSubject } from 'rxjs';
-
-export function getEsClient({
-  esRequestTimeout,
-  esApiVersion,
-  http,
-  packageVersion,
-}: {
-  esRequestTimeout: number;
-  esApiVersion: string;
-  http: CoreStart['http'];
-  packageVersion: PackageInfo['version'];
-}) {
-  // Use legacy es client for msearch.
-  const client = es.Client({
-    host: getEsUrl(http, packageVersion),
-    log: 'info',
-    requestTimeout: esRequestTimeout,
-    apiVersion: esApiVersion,
-  });
-
-  const loadingCount$ = new BehaviorSubject(0);
-  http.addLoadingCountSource(loadingCount$);
-
-  return {
-    search: wrapEsClientMethod(client, 'search', loadingCount$),
-    msearch: wrapEsClientMethod(client, 'msearch', loadingCount$),
-    create: wrapEsClientMethod(client, 'create', loadingCount$),
-  };
-}
-
-function wrapEsClientMethod(esClient: any, method: string, loadingCount$: BehaviorSubject<number>) {
-  return (args: any) => {
-    // esClient returns a promise, with an additional abort handler
-    // To tap into the abort handling, we have to override that abort handler.
-    const customPromiseThingy = esClient[method](args);
-    const { abort } = customPromiseThingy;
-    let resolved = false;
-
-    // Start LoadingIndicator
-    loadingCount$.next(loadingCount$.getValue() + 1);
-
-    // Stop LoadingIndicator when user aborts
-    customPromiseThingy.abort = () => {
-      abort();
-      if (!resolved) {
-        resolved = true;
-        loadingCount$.next(loadingCount$.getValue() - 1);
-      }
-    };
-
-    // Stop LoadingIndicator when promise finishes
-    customPromiseThingy.finally(() => {
-      resolved = true;
-      loadingCount$.next(loadingCount$.getValue() - 1);
-    });
-
-    return customPromiseThingy;
-  };
-}
-
-function getEsUrl(http: CoreStart['http'], packageVersion: PackageInfo['version']) {
-  const a = document.createElement('a');
-  a.href = http.basePath.prepend('/elasticsearch');
-  const protocolPort = /https/.test(a.protocol) ? 443 : 80;
-  const port = a.port || protocolPort;
-  return {
-    host: a.hostname,
-    port,
-    protocol: a.protocol,
-    pathname: a.pathname,
-    headers: {
-      'kbn-version': packageVersion,
-    },
-  };
-}

src/plugins/data/public/search/legacy/get_msearch_params.test.ts

@@ -1,64 +0,0 @@
-/*
- * Licensed to Elasticsearch B.V. under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch B.V. licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-import { getMSearchParams } from './get_msearch_params';
-import { GetConfigFn, UI_SETTINGS } from '../../../common';
-
-function getConfigStub(config: any = {}): GetConfigFn {
-  return (key) => config[key];
-}
-
-describe('getMSearchParams', () => {
-  test('includes rest_total_hits_as_int', () => {
-    const config = getConfigStub();
-    const msearchParams = getMSearchParams(config);
-    expect(msearchParams.rest_total_hits_as_int).toBe(true);
-  });
-
-  test('includes ignore_throttled according to search:includeFrozen', () => {
-    let config = getConfigStub({ [UI_SETTINGS.SEARCH_INCLUDE_FROZEN]: true });
-    let msearchParams = getMSearchParams(config);
-    expect(msearchParams.ignore_throttled).toBe(false);
-
-    config = getConfigStub({ [UI_SETTINGS.SEARCH_INCLUDE_FROZEN]: false });
-    msearchParams = getMSearchParams(config);
-    expect(msearchParams.ignore_throttled).toBe(true);
-  });
-
-  test('includes max_concurrent_shard_requests according to courier:maxConcurrentShardRequests if greater than 0', () => {
-    let config = getConfigStub({ [UI_SETTINGS.COURIER_MAX_CONCURRENT_SHARD_REQUESTS]: 0 });
-    let msearchParams = getMSearchParams(config);
-    expect(msearchParams.max_concurrent_shard_requests).toBe(undefined);
-
-    config = getConfigStub({ [UI_SETTINGS.COURIER_MAX_CONCURRENT_SHARD_REQUESTS]: 5 });
-    msearchParams = getMSearchParams(config);
-    expect(msearchParams.max_concurrent_shard_requests).toBe(5);
-  });
-
-  test('does not include other search params that are included in the msearch header or body', () => {
-    const config = getConfigStub({
-      [UI_SETTINGS.SEARCH_INCLUDE_FROZEN]: false,
-      [UI_SETTINGS.COURIER_MAX_CONCURRENT_SHARD_REQUESTS]: 5,
-    });
-    const msearchParams = getMSearchParams(config);
-    expect(msearchParams.hasOwnProperty('ignore_unavailable')).toBe(false);
-    expect(msearchParams.hasOwnProperty('preference')).toBe(false);
-    expect(msearchParams.hasOwnProperty('timeout')).toBe(false);
-  });
-});

src/plugins/data/public/search/legacy/get_msearch_params.ts

@@ -1,29 +0,0 @@
-/*
- * Licensed to Elasticsearch B.V. under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch B.V. licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-import { GetConfigFn } from '../../../common';
-import { getIgnoreThrottled, getMaxConcurrentShardRequests } from '../fetch';
-
-export function getMSearchParams(getConfig: GetConfigFn) {
-  return {
-    rest_total_hits_as_int: true,
-    ignore_throttled: getIgnoreThrottled(getConfig),
-    max_concurrent_shard_requests: getMaxConcurrentShardRequests(getConfig),
-  };
-}

src/plugins/data/public/search/legacy/index.ts

@@ -18,4 +18,3 @@
  */
 
 export { fetchSoon } from './fetch_soon';
-export { getEsClient, LegacyApiCaller } from './es_client';

src/plugins/data/public/search/mocks.ts

@@ -35,12 +35,6 @@ function createStartContract(): jest.Mocked<ISearchStart> {
     aggs: searchAggsStartMock(),
     search: jest.fn(),
     searchSource: searchSourceMock,
-    __LEGACY: {
-      esClient: {
-        search: jest.fn(),
-        msearch: jest.fn(),
-      },
-    },
   };
 }
 

src/plugins/data/public/search/search_service.ts

@@ -17,11 +17,11 @@
  * under the License.
  */
 
-import { Plugin, CoreSetup, CoreStart, PackageInfo } from 'src/core/public';
+import { Plugin, CoreSetup, CoreStart } from 'src/core/public';
+import { BehaviorSubject } from 'rxjs';
 import { ISearchSetup, ISearchStart, SearchEnhancements } from './types';
 
 import { createSearchSource, SearchSource, SearchSourceDependencies } from './search_source';
-import { getEsClient, LegacyApiCaller } from './legacy';
 import { AggsService, AggsStartDependencies } from './aggs';
 import { IndexPatternsContract } from '../index_patterns/index_patterns';
 import { ISearchInterceptor, SearchInterceptor } from './search_interceptor';
@@ -33,9 +33,8 @@ import { ExpressionsSetup } from '../../../expressions/public';
 
 /** @internal */
 export interface SearchServiceSetupDependencies {
-  packageInfo: PackageInfo;
-  usageCollection?: UsageCollectionSetup;
   expressions: ExpressionsSetup;
+  usageCollection?: UsageCollectionSetup;
 }
 
 /** @internal */
@@ -45,28 +44,18 @@ export interface SearchServiceStartDependencies {
 }
 
 export class SearchService implements Plugin<ISearchSetup, ISearchStart> {
-  private esClient?: LegacyApiCaller;
   private readonly aggsService = new AggsService();
   private searchInterceptor!: ISearchInterceptor;
   private usageCollector?: SearchUsageCollector;
 
   public setup(
     { http, getStartServices, injectedMetadata, notifications, uiSettings }: CoreSetup,
-    { expressions, packageInfo, usageCollection }: SearchServiceSetupDependencies
+    { expressions, usageCollection }: SearchServiceSetupDependencies
   ): ISearchSetup {
-    const esApiVersion = injectedMetadata.getInjectedVar('esApiVersion') as string;
     const esRequestTimeout = injectedMetadata.getInjectedVar('esRequestTimeout') as number;
-    const packageVersion = packageInfo.version;
 
     this.usageCollector = createUsageCollector(getStartServices, usageCollection);
 
-    this.esClient = getEsClient({
-      esRequestTimeout,
-      esApiVersion,
-      http,
-      packageVersion,
-    });
-
     /**
      * A global object that intercepts all searches and provides convenience methods for cancelling
      * all pending search requests, as well as getting the number of pending search requests.
@@ -107,15 +96,16 @@ export class SearchService implements Plugin<ISearchSetup, ISearchStart> {
       return this.searchInterceptor.search(request, options);
     }) as ISearchGeneric;
 
-    const legacySearch = {
-      esClient: this.esClient!,
-    };
+    const loadingCount$ = new BehaviorSubject(0);
+    http.addLoadingCountSource(loadingCount$);
 
     const searchSourceDependencies: SearchSourceDependencies = {
       getConfig: uiSettings.get.bind(uiSettings),
+      // TODO: we don't need this, apply on the server
       esShardTimeout: injectedMetadata.getInjectedVar('esShardTimeout') as number,
       search,
-      legacySearch,
+      http,
+      loadingCount$,
     };
 
     return {
@@ -127,7 +117,6 @@ export class SearchService implements Plugin<ISearchSetup, ISearchStart> {
           return new SearchSource({}, searchSourceDependencies);
         },
       },
-      __LEGACY: legacySearch,
     };
   }
 

src/plugins/data/public/search/search_source/create_search_source.test.ts

@@ -22,7 +22,8 @@ import { SearchSourceDependencies } from './search_source';
 import { IIndexPattern } from '../../../common/index_patterns';
 import { IndexPatternsContract } from '../../index_patterns/index_patterns';
 import { Filter } from '../../../common/es_query/filters';
-import { dataPluginMock } from '../../mocks';
+import { coreMock } from '../../../../../core/public/mocks';
+import { BehaviorSubject } from 'rxjs';
 
 describe('createSearchSource', () => {
   const indexPatternMock: IIndexPattern = {} as IIndexPattern;
@@ -31,13 +32,12 @@ describe('createSearchSource', () => {
   let createSearchSource: ReturnType<typeof createSearchSourceFactory>;
 
   beforeEach(() => {
-    const data = dataPluginMock.createStartContract();
-
     dependencies = {
       getConfig: jest.fn(),
       search: jest.fn(),
-      legacySearch: data.search.__LEGACY,
       esShardTimeout: 30000,
+      http: coreMock.createStart().http,
+      loadingCount$: new BehaviorSubject(0),
     };
 
     indexPatternContractMock = ({

src/plugins/data/public/search/search_source/mocks.ts

@@ -17,7 +17,8 @@
  * under the License.
  */
 
-import { uiSettingsServiceMock } from '../../../../../core/public/mocks';
+import { BehaviorSubject } from 'rxjs';
+import { httpServiceMock, uiSettingsServiceMock } from '../../../../../core/public/mocks';
 
 import { ISearchSource, SearchSource } from './search_source';
 import { SearchSourceFields } from './types';
@@ -54,10 +55,6 @@ export const createSearchSourceMock = (fields?: SearchSourceFields) =>
     getConfig: uiSettingsServiceMock.createStartContract().get,
     esShardTimeout: 30000,
     search: jest.fn(),
-    legacySearch: {
-      esClient: {
-        search: jest.fn(),
-        msearch: jest.fn(),
-      },
-    },
+    http: httpServiceMock.createStartContract(),
+    loadingCount$: new BehaviorSubject(0),
   });

src/plugins/data/public/search/search_source/search_source.test.ts

@@ -17,12 +17,12 @@
  * under the License.
  */
 
-import { Observable } from 'rxjs';
+import { Observable, BehaviorSubject } from 'rxjs';
 import { GetConfigFn } from 'src/plugins/data/common';
 import { SearchSource, SearchSourceDependencies } from './search_source';
 import { IndexPattern, SortDirection } from '../..';
 import { fetchSoon } from '../legacy';
-import { dataPluginMock } from '../../../../data/public/mocks';
+import { coreMock } from '../../../../../core/public/mocks';
 
 jest.mock('../legacy', () => ({
   fetchSoon: jest.fn().mockResolvedValue({}),
@@ -54,8 +54,6 @@ describe('SearchSource', () => {
   let searchSourceDependencies: SearchSourceDependencies;
 
   beforeEach(() => {
-    const data = dataPluginMock.createStartContract();
-
     mockSearchMethod = jest.fn(() => {
       return new Observable((subscriber) => {
         setTimeout(() => {
@@ -70,8 +68,9 @@ describe('SearchSource', () => {
     searchSourceDependencies = {
       getConfig: jest.fn(),
       search: mockSearchMethod,
-      legacySearch: data.search.__LEGACY,
       esShardTimeout: 30000,
+      http: coreMock.createStart().http,
+      loadingCount$: new BehaviorSubject(0),
     };
   });
 

src/plugins/data/public/search/search_source/search_source.ts

@@ -72,6 +72,8 @@
 import { setWith } from '@elastic/safer-lodash-set';
 import { uniqueId, uniq, extend, pick, difference, omit, isObject, keys, isFunction } from 'lodash';
 import { map } from 'rxjs/operators';
+import { HttpStart } from 'src/core/public';
+import { BehaviorSubject } from 'rxjs';
 import { normalizeSortRequest } from './normalize_sort_request';
 import { filterDocvalueFields } from './filter_docvalue_fields';
 import { fieldWildcardFilter } from '../../../../kibana_utils/common';
@@ -95,7 +97,6 @@ import { getHighlightRequest } from '../../../common/field_formats';
 import { GetConfigFn } from '../../../common/types';
 import { fetchSoon } from '../legacy';
 import { extractReferences } from './extract_references';
-import { ISearchStartLegacy } from '../types';
 
 /** @internal */
 export const searchSourceRequiredUiSettings = [
@@ -116,8 +117,9 @@ export const searchSourceRequiredUiSettings = [
 export interface SearchSourceDependencies {
   getConfig: GetConfigFn;
   search: ISearchGeneric;
-  legacySearch: ISearchStartLegacy;
+  http: HttpStart;
   esShardTimeout: number;
+  loadingCount$: BehaviorSubject<number>;
 }
 
 /** @public **/
@@ -248,7 +250,7 @@ export class SearchSource {
    * @return {Promise<SearchResponse<unknown>>}
    */
   private async legacyFetch(searchRequest: SearchRequest, options: ISearchOptions) {
-    const { esShardTimeout, legacySearch, getConfig } = this.dependencies;
+    const { http, getConfig, loadingCount$ } = this.dependencies;
 
     return await fetchSoon(
       searchRequest,
@@ -257,9 +259,9 @@ export class SearchSource {
         ...options,
       },
       {
-        legacySearchService: legacySearch,
+        http,
         config: { get: getConfig },
-        esShardTimeout,
+        loadingCount$,
       }
     );
   }

src/plugins/data/public/search/types.ts

@@ -19,7 +19,6 @@
 
 import { Observable } from 'rxjs';
 import { PackageInfo } from 'kibana/server';
-import { LegacyApiCaller } from './legacy/es_client';
 import { ISearchInterceptor } from './search_interceptor';
 import { ISearchSource, SearchSourceFields } from './search_source';
 import { SearchUsageCollector } from './collectors';
@@ -47,10 +46,6 @@ export type ISearchGeneric = <
   options?: ISearchOptions
 ) => Observable<SearchStrategyResponse>;
 
-export interface ISearchStartLegacy {
-  esClient: LegacyApiCaller;
-}
-
 export interface SearchEnhancements {
   searchInterceptor: ISearchInterceptor;
 }
@@ -74,11 +69,6 @@ export interface ISearchStart {
     create: (fields?: SearchSourceFields) => Promise<ISearchSource>;
     createEmpty: () => ISearchSource;
   };
-  /**
-   * @deprecated
-   * @internal
-   */
-  __LEGACY: ISearchStartLegacy;
 }
 
 export { SEARCH_EVENT_TYPE } from './collectors';

src/plugins/data/server/search/routes/index.ts

@@ -17,5 +17,5 @@
  * under the License.
  */
 
-export { getEsClient } from './get_es_client';
-export { LegacyApiCaller } from './types';
+export * from './msearch';
+export * from './search';

src/plugins/data/server/search/routes/msearch.test.ts

@@ -0,0 +1,150 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { Observable } from 'rxjs';
+
+import {
+  CoreSetup,
+  RequestHandlerContext,
+  SharedGlobalConfig,
+  StartServicesAccessor,
+} from 'src/core/server';
+import {
+  coreMock,
+  httpServerMock,
+  pluginInitializerContextConfigMock,
+} from '../../../../../../src/core/server/mocks';
+import { registerMsearchRoute, convertRequestBody } from './msearch';
+import { DataPluginStart } from '../../plugin';
+import { dataPluginMock } from '../../mocks';
+
+describe('msearch route', () => {
+  let mockDataStart: MockedKeys<DataPluginStart>;
+  let mockCoreSetup: MockedKeys<CoreSetup<{}, DataPluginStart>>;
+  let getStartServices: jest.Mocked<StartServicesAccessor<{}, DataPluginStart>>;
+  let globalConfig$: Observable<SharedGlobalConfig>;
+
+  beforeEach(() => {
+    mockDataStart = dataPluginMock.createStartContract();
+    mockCoreSetup = coreMock.createSetup({ pluginStartContract: mockDataStart });
+    getStartServices = mockCoreSetup.getStartServices;
+    globalConfig$ = pluginInitializerContextConfigMock({}).legacy.globalConfig$;
+  });
+
+  it('handler calls /_msearch with the given request', async () => {
+    const response = { id: 'yay' };
+    const mockClient = { transport: { request: jest.fn().mockResolvedValue(response) } };
+    const mockContext = {
+      core: {
+        elasticsearch: { client: { asCurrentUser: mockClient } },
+        uiSettings: { client: { get: jest.fn() } },
+      },
+    };
+    const mockBody = { searches: [{ header: {}, body: {} }] };
+    const mockQuery = {};
+    const mockRequest = httpServerMock.createKibanaRequest({
+      body: mockBody,
+      query: mockQuery,
+    });
+    const mockResponse = httpServerMock.createResponseFactory();
+
+    registerMsearchRoute(mockCoreSetup.http.createRouter(), { getStartServices, globalConfig$ });
+
+    const mockRouter = mockCoreSetup.http.createRouter.mock.results[0].value;
+    const handler = mockRouter.post.mock.calls[0][1];
+    await handler((mockContext as unknown) as RequestHandlerContext, mockRequest, mockResponse);
+
+    expect(mockClient.transport.request.mock.calls[0][0].method).toBe('GET');
+    expect(mockClient.transport.request.mock.calls[0][0].path).toBe('/_msearch');
+    expect(mockClient.transport.request.mock.calls[0][0].body).toEqual(
+      convertRequestBody(mockBody as any, { timeout: '0ms' })
+    );
+    expect(mockResponse.ok).toBeCalled();
+    expect(mockResponse.ok.mock.calls[0][0]).toEqual({
+      body: response,
+    });
+  });
+
+  it('handler throws an error if the search throws an error', async () => {
+    const response = {
+      message: 'oh no',
+      body: {
+        error: 'oops',
+      },
+    };
+    const mockClient = {
+      transport: { request: jest.fn().mockReturnValue(Promise.reject(response)) },
+    };
+    const mockContext = {
+      core: {
+        elasticsearch: { client: { asCurrentUser: mockClient } },
+        uiSettings: { client: { get: jest.fn() } },
+      },
+    };
+    const mockBody = { searches: [{ header: {}, body: {} }] };
+    const mockQuery = {};
+    const mockRequest = httpServerMock.createKibanaRequest({
+      body: mockBody,
+      query: mockQuery,
+    });
+    const mockResponse = httpServerMock.createResponseFactory();
+
+    registerMsearchRoute(mockCoreSetup.http.createRouter(), { getStartServices, globalConfig$ });
+
+    const mockRouter = mockCoreSetup.http.createRouter.mock.results[0].value;
+    const handler = mockRouter.post.mock.calls[0][1];
+    await handler((mockContext as unknown) as RequestHandlerContext, mockRequest, mockResponse);
+
+    expect(mockClient.transport.request).toBeCalled();
+    expect(mockResponse.customError).toBeCalled();
+
+    const error: any = mockResponse.customError.mock.calls[0][0];
+    expect(error.body.message).toBe('oh no');
+    expect(error.body.attributes.error).toBe('oops');
+  });
+
+  describe('convertRequestBody', () => {
+    it('combines header & body into proper msearch request', () => {
+      const request = {
+        searches: [{ header: { index: 'foo', preference: 0 }, body: { test: true } }],
+      };
+      expect(convertRequestBody(request, { timeout: '30000ms' })).toMatchInlineSnapshot(`
+        "{\\"ignore_unavailable\\":true,\\"index\\":\\"foo\\",\\"preference\\":0}
+        {\\"timeout\\":\\"30000ms\\",\\"test\\":true}
+        "
+      `);
+    });
+
+    it('handles multiple searches', () => {
+      const request = {
+        searches: [
+          { header: { index: 'foo', preference: 0 }, body: { test: true } },
+          { header: { index: 'bar', preference: 1 }, body: { hello: 'world' } },
+        ],
+      };
+      expect(convertRequestBody(request, { timeout: '30000ms' })).toMatchInlineSnapshot(`
+        "{\\"ignore_unavailable\\":true,\\"index\\":\\"foo\\",\\"preference\\":0}
+        {\\"timeout\\":\\"30000ms\\",\\"test\\":true}
+        {\\"ignore_unavailable\\":true,\\"index\\":\\"bar\\",\\"preference\\":1}
+        {\\"timeout\\":\\"30000ms\\",\\"hello\\":\\"world\\"}
+        "
+      `);
+    });
+  });
+});

src/plugins/data/server/search/routes/msearch.ts

@@ -0,0 +1,136 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { first } from 'rxjs/operators';
+import { schema } from '@kbn/config-schema';
+
+import { IRouter } from 'src/core/server';
+import { UI_SETTINGS } from '../../../common';
+import { SearchRouteDependencies } from '../search_service';
+import { getDefaultSearchParams } from '..';
+
+interface MsearchHeaders {
+  index: string;
+  preference?: number | string;
+}
+
+interface MsearchRequest {
+  header: MsearchHeaders;
+  body: any;
+}
+
+interface RequestBody {
+  searches: MsearchRequest[];
+}
+
+/** @internal */
+export function convertRequestBody(
+  requestBody: RequestBody,
+  { timeout }: { timeout?: string }
+): string {
+  return requestBody.searches.reduce((req, curr) => {
+    const header = JSON.stringify({
+      ignore_unavailable: true,
+      ...curr.header,
+    });
+    const body = JSON.stringify({
+      timeout,
+      ...curr.body,
+    });
+    return `${req}${header}\n${body}\n`;
+  }, '');
+}
+
+/**
+ * The msearch route takes in an array of searches, each consisting of header
+ * and body json, and reformts them into a single request for the _msearch API.
+ *
+ * The reason for taking requests in a different format is so that we can
+ * inject values into each request without needing to manually parse each one.
+ *
+ * This route is internal and _should not be used_ in any new areas of code.
+ * It only exists as a means of removing remaining dependencies on the
+ * legacy ES client.
+ *
+ * @deprecated
+ */
+export function registerMsearchRoute(router: IRouter, deps: SearchRouteDependencies): void {
+  router.post(
+    {
+      path: '/internal/_msearch',
+      validate: {
+        body: schema.object({
+          searches: schema.arrayOf(
+            schema.object({
+              header: schema.object(
+                {
+                  index: schema.string(),
+                  preference: schema.maybe(schema.oneOf([schema.number(), schema.string()])),
+                },
+                { unknowns: 'allow' }
+              ),
+              body: schema.object({}, { unknowns: 'allow' }),
+            })
+          ),
+        }),
+      },
+    },
+    async (context, request, res) => {
+      const client = context.core.elasticsearch.client.asCurrentUser;
+
+      // get shardTimeout
+      const config = await deps.globalConfig$.pipe(first()).toPromise();
+      const { timeout } = getDefaultSearchParams(config);
+
+      const body = convertRequestBody(request.body, { timeout });
+
+      try {
+        const ignoreThrottled = !(await context.core.uiSettings.client.get(
+          UI_SETTINGS.SEARCH_INCLUDE_FROZEN
+        ));
+        const maxConcurrentShardRequests = await context.core.uiSettings.client.get(
+          UI_SETTINGS.COURIER_MAX_CONCURRENT_SHARD_REQUESTS
+        );
+        const response = await client.transport.request({
+          method: 'GET',
+          path: '/_msearch',
+          body,
+          querystring: {
+            rest_total_hits_as_int: true,
+            ignore_throttled: ignoreThrottled,
+            max_concurrent_shard_requests:
+              maxConcurrentShardRequests > 0 ? maxConcurrentShardRequests : undefined,
+          },
+        });
+
+        return res.ok({ body: response });
+      } catch (err) {
+        return res.customError({
+          statusCode: err.statusCode || 500,
+          body: {
+            message: err.message,
+            attributes: {
+              error: err.body?.error || err.message,
+            },
+          },
+        });
+      }
+    }
+  );
+}

src/plugins/data/server/search/routes/search.test.ts

@@ -17,19 +17,34 @@
  * under the License.
  */
 
-import { CoreSetup, RequestHandlerContext } from '../../../../../src/core/server';
-import { coreMock, httpServerMock } from '../../../../../src/core/server/mocks';
-import { registerSearchRoute } from './routes';
-import { DataPluginStart } from '../plugin';
-import { dataPluginMock } from '../mocks';
+import { Observable } from 'rxjs';
+
+import {
+  CoreSetup,
+  RequestHandlerContext,
+  SharedGlobalConfig,
+  StartServicesAccessor,
+} from 'src/core/server';
+import {
+  coreMock,
+  httpServerMock,
+  pluginInitializerContextConfigMock,
+} from '../../../../../../src/core/server/mocks';
+import { registerSearchRoute } from './search';
+import { DataPluginStart } from '../../plugin';
+import { dataPluginMock } from '../../mocks';
 
 describe('Search service', () => {
   let mockDataStart: MockedKeys<DataPluginStart>;
-  let mockCoreSetup: MockedKeys<CoreSetup<object, DataPluginStart>>;
+  let mockCoreSetup: MockedKeys<CoreSetup<{}, DataPluginStart>>;
+  let getStartServices: jest.Mocked<StartServicesAccessor<{}, DataPluginStart>>;
+  let globalConfig$: Observable<SharedGlobalConfig>;
 
   beforeEach(() => {
     mockDataStart = dataPluginMock.createStartContract();
     mockCoreSetup = coreMock.createSetup({ pluginStartContract: mockDataStart });
+    getStartServices = mockCoreSetup.getStartServices;
+    globalConfig$ = pluginInitializerContextConfigMock({}).legacy.globalConfig$;
   });
 
   it('handler calls context.search.search with the given request and strategy', async () => {
@@ -44,7 +59,7 @@ describe('Search service', () => {
     });
     const mockResponse = httpServerMock.createResponseFactory();
 
-    registerSearchRoute(mockCoreSetup);
+    registerSearchRoute(mockCoreSetup.http.createRouter(), { getStartServices, globalConfig$ });
 
     const mockRouter = mockCoreSetup.http.createRouter.mock.results[0].value;
     const handler = mockRouter.post.mock.calls[0][1];
@@ -75,7 +90,7 @@ describe('Search service', () => {
     });
     const mockResponse = httpServerMock.createResponseFactory();
 
-    registerSearchRoute(mockCoreSetup);
+    registerSearchRoute(mockCoreSetup.http.createRouter(), { getStartServices, globalConfig$ });
 
     const mockRouter = mockCoreSetup.http.createRouter.mock.results[0].value;
     const handler = mockRouter.post.mock.calls[0][1];

src/plugins/data/server/search/routes/search.ts

@@ -18,13 +18,14 @@
  */
 
 import { schema } from '@kbn/config-schema';
-import { CoreSetup } from '../../../../core/server';
-import { getRequestAbortedSignal } from '../lib';
-import { DataPluginStart } from '../plugin';
-
-export function registerSearchRoute(core: CoreSetup<object, DataPluginStart>): void {
-  const router = core.http.createRouter();
+import { IRouter } from 'src/core/server';
+import { getRequestAbortedSignal } from '../../lib';
+import { SearchRouteDependencies } from '../search_service';
 
+export function registerSearchRoute(
+  router: IRouter,
+  { getStartServices }: SearchRouteDependencies
+): void {
   router.post(
     {
       path: '/internal/search/{strategy}/{id?}',
@@ -44,7 +45,7 @@ export function registerSearchRoute(core: CoreSetup<object, DataPluginStart>): v
       const { strategy, id } = request.params;
       const abortSignal = getRequestAbortedSignal(request.events.aborted$);
 
-      const [, , selfStart] = await core.getStartServices();
+      const [, , selfStart] = await getStartServices();
 
       try {
         const response = await selfStart.search.search(
@@ -85,7 +86,7 @@ export function registerSearchRoute(core: CoreSetup<object, DataPluginStart>): v
     async (context, request, res) => {
       const { strategy, id } = request.params;
 
-      const [, , selfStart] = await core.getStartServices();
+      const [, , selfStart] = await getStartServices();
       const searchStrategy = selfStart.search.getSearchStrategy(strategy);
       if (!searchStrategy.cancel) return res.ok();
 

src/plugins/data/server/search/search_service.ts

@@ -17,6 +17,7 @@
  * under the License.
  */
 
+import { Observable } from 'rxjs';
 import {
   CoreSetup,
   CoreStart,
@@ -24,13 +25,15 @@ import {
   Plugin,
   PluginInitializerContext,
   RequestHandlerContext,
-} from '../../../../core/server';
+  SharedGlobalConfig,
+  StartServicesAccessor,
+} from 'src/core/server';
 import { ISearchSetup, ISearchStart, ISearchStrategy, SearchEnhancements } from './types';
 
 import { AggsService, AggsSetupDependencies } from './aggs';
 
 import { FieldFormatsStart } from '../field_formats';
-import { registerSearchRoute } from './routes';
+import { registerMsearchRoute, registerSearchRoute } from './routes';
 import { ES_SEARCH_STRATEGY, esSearchStrategyProvider } from './es_search';
 import { DataPluginStart } from '../plugin';
 import { UsageCollectionSetup } from '../../../usage_collection/server';
@@ -55,6 +58,12 @@ export interface SearchServiceStartDependencies {
   fieldFormats: FieldFormatsStart;
 }
 
+/** @internal */
+export interface SearchRouteDependencies {
+  getStartServices: StartServicesAccessor<{}, DataPluginStart>;
+  globalConfig$: Observable<SharedGlobalConfig>;
+}
+
 export class SearchService implements Plugin<ISearchSetup, ISearchStart> {
   private readonly aggsService = new AggsService();
   private defaultSearchStrategyName: string = ES_SEARCH_STRATEGY;
@@ -66,11 +75,19 @@ export class SearchService implements Plugin<ISearchSetup, ISearchStart> {
   ) {}
 
   public setup(
-    core: CoreSetup<object, DataPluginStart>,
+    core: CoreSetup<{}, DataPluginStart>,
     { registerFunction, usageCollection }: SearchServiceSetupDependencies
   ): ISearchSetup {
     const usage = usageCollection ? usageProvider(core) : undefined;
 
+    const router = core.http.createRouter();
+    const routeDependencies = {
+      getStartServices: core.getStartServices,
+      globalConfig$: this.initializerContext.config.legacy.globalConfig$,
+    };
+    registerSearchRoute(router, routeDependencies);
+    registerMsearchRoute(router, routeDependencies);
+
     this.registerSearchStrategy(
       ES_SEARCH_STRATEGY,
       esSearchStrategyProvider(
@@ -85,8 +102,6 @@ export class SearchService implements Plugin<ISearchSetup, ISearchStart> {
       registerUsageCollector(usageCollection, this.initializerContext);
     }
 
-    registerSearchRoute(core);
-
     return {
       __enhance: (enhancements: SearchEnhancements) => {
         if (this.searchStrategies.hasOwnProperty(enhancements.defaultStrategy)) {

test/api_integration/apis/index.js

@@ -28,6 +28,7 @@ export default function ({ loadTestFile }) {
     loadTestFile(require.resolve('./saved_objects_management'));
     loadTestFile(require.resolve('./saved_objects'));
     loadTestFile(require.resolve('./scripts'));
+    loadTestFile(require.resolve('./search'));
     loadTestFile(require.resolve('./shorten'));
     loadTestFile(require.resolve('./suggestions'));
     loadTestFile(require.resolve('./status'));

test/api_integration/apis/search/index.ts

@@ -17,14 +17,10 @@
  * under the License.
  */
 
-import { SearchResponse } from 'elasticsearch';
-import { SearchRequest } from '../../fetch';
+import { FtrProviderContext } from '../../ftr_provider_context';
 
-export interface LegacyApiCaller {
-  search: (searchRequest: SearchRequest) => LegacyApiCallerResponse;
-  msearch: (searchRequest: SearchRequest) => LegacyApiCallerResponse;
-}
-
-interface LegacyApiCallerResponse extends Promise<SearchResponse<any>> {
-  abort: () => void;
+export default function ({ loadTestFile }: FtrProviderContext) {
+  describe('search', () => {
+    loadTestFile(require.resolve('./search'));
+  });
 }

test/api_integration/apis/search/search.ts

@@ -0,0 +1,88 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { FtrProviderContext } from '../../ftr_provider_context';
+
+export default function ({ getService }: FtrProviderContext) {
+  const supertest = getService('supertest');
+
+  describe('msearch', () => {
+    describe('post', () => {
+      it('should return 200 when correctly formatted searches are provided', async () =>
+        await supertest
+          .post(`/internal/_msearch`)
+          .send({
+            searches: [
+              {
+                header: { index: 'foo' },
+                body: {
+                  query: {
+                    match_all: {},
+                  },
+                },
+              },
+            ],
+          })
+          .expect(200));
+
+      it('should return 400 if you provide malformed content', async () =>
+        await supertest
+          .post(`/internal/_msearch`)
+          .send({
+            foo: false,
+          })
+          .expect(400));
+
+      it('should require you to provide an index for each request', async () =>
+        await supertest
+          .post(`/internal/_msearch`)
+          .send({
+            searches: [
+              { header: { index: 'foo' }, body: {} },
+              { header: {}, body: {} },
+            ],
+          })
+          .expect(400));
+
+      it('should not require optional params', async () =>
+        await supertest
+          .post(`/internal/_msearch`)
+          .send({
+            searches: [{ header: { index: 'foo' }, body: {} }],
+          })
+          .expect(200));
+
+      it('should allow passing preference as a string', async () =>
+        await supertest
+          .post(`/internal/_msearch`)
+          .send({
+            searches: [{ header: { index: 'foo', preference: '_custom' }, body: {} }],
+          })
+          .expect(200));
+
+      it('should allow passing preference as a number', async () =>
+        await supertest
+          .post(`/internal/_msearch`)
+          .send({
+            searches: [{ header: { index: 'foo', preference: 123 }, body: {} }],
+          })
+          .expect(200));
+    });
+  });
+}

yarn.lock

@@ -11330,11 +11330,6 @@ elastic-apm-node@^3.7.0:
     traceparent "^1.0.0"
     unicode-byte-truncate "^1.0.0"
 
-elasticsearch-browser@^16.7.0:
-  version "16.7.0"
-  resolved "https://registry.yarnpkg.com/elasticsearch-browser/-/elasticsearch-browser-16.7.0.tgz#1f32a402cd36a9bb14a9ea6cb70f8e126d4cb9b1"
-  integrity sha512-UES2Fbnzy4Ivq4QvES4sfk/a5UytJczeJdfxRWa4kuHEllKOffKQLTxJ8Ti86OREpACQxppqvYgzctJuEiIr7Q==
-
 elasticsearch@^16.4.0:
   version "16.5.0"
   resolved "https://registry.yarnpkg.com/elasticsearch/-/elasticsearch-16.5.0.tgz#619a48040be25d345fdddf09fa6042a88c3974d6"