[Enterprise Search] [Search application] List indices fetch indices stats from ES directly (#153696)

## Summary

This PR adds a lib file to fetch indices stats of an search application from Elasticsearch directly

### Screenshot

#### List page indices 
<img width="1728" alt="List page indices"
src="https://user-images.githubusercontent.com/55930906/227617672-bfcdd3e4-85c2-4432-bcee-2aa3f5be07a4.png">

#### Overview page indices 
<img width="1728" alt="Overview page indices "
src="https://user-images.githubusercontent.com/55930906/227617828-afa01bf6-5f23-4f3f-9ff6-75f6c5dbcff2.png">

### Checklist


- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

---------

Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>

x-pack/plugins/enterprise_search/public/applications/enterprise_search_content/components/engines/engines_list_flyout_logic.test.ts

@@ -16,11 +16,11 @@ import { FetchEngineApiLogic } from '../../api/engines/fetch_engine_api_logic';
 import { EngineListFlyoutValues, EnginesListFlyoutLogic } from './engines_list_flyout_logic';
 
 const DEFAULT_VALUES: EngineListFlyoutValues = {
+  fetchEngineApiError: undefined,
+  fetchEngineApiStatus: Status.IDLE,
   fetchEngineData: undefined,
   fetchEngineName: null,
   isFetchEngineFlyoutVisible: false,
-  fetchEngineApiStatus: Status.IDLE,
-  fetchEngineApiError: undefined,
   isFetchEngineLoading: false,
 };
 const mockEngineData: EnterpriseSearchEngineDetails = {
@@ -66,10 +66,10 @@ describe('EngineListFlyoutLogic', () => {
         EnginesListFlyoutLogic.actions.openFetchEngineFlyout('my-test-engine');
         expect(EnginesListFlyoutLogic.values).toEqual({
           ...DEFAULT_VALUES,
-          isFetchEngineFlyoutVisible: true,
-          fetchEngineName: 'my-test-engine',
-          isFetchEngineLoading: true,
           fetchEngineApiStatus: Status.LOADING,
+          fetchEngineName: 'my-test-engine',
+          isFetchEngineFlyoutVisible: true,
+          isFetchEngineLoading: true,
         });
       });
     });

x-pack/plugins/enterprise_search/public/applications/enterprise_search_content/components/engines/engines_list_logic.ts

@@ -50,8 +50,8 @@ export type EnginesListActions = Pick<
   openDeleteEngineModal: (engine: EnterpriseSearchEngine | EnterpriseSearchEngineDetails) => {
     engine: EnterpriseSearchEngine;
   };
-  setIsFirstRequest(): void;
   openEngineCreate(): void;
+  setIsFirstRequest(): void;
   setSearchQuery(searchQuery: string): { searchQuery: string };
 };
 
@@ -74,6 +74,16 @@ interface EngineListValues {
 }
 
 export const EnginesListLogic = kea<MakeLogicType<EngineListValues, EnginesListActions>>({
+  actions: {
+    closeDeleteEngineModal: true,
+    closeEngineCreate: true,
+    fetchEngines: true,
+    onPaginate: (args: EuiBasicTableOnChange) => ({ pageNumber: args.page.index }),
+    openDeleteEngineModal: (engine) => ({ engine }),
+    openEngineCreate: true,
+    setIsFirstRequest: true,
+    setSearchQuery: (searchQuery: string) => ({ searchQuery }),
+  },
   connect: {
     actions: [
       FetchEnginesAPILogic,
@@ -88,17 +98,18 @@ export const EnginesListLogic = kea<MakeLogicType<EngineListValues, EnginesListA
       ['status as deleteStatus'],
     ],
   },
-  actions: {
-    closeDeleteEngineModal: true,
-    closeEngineCreate: true,
-    fetchEngines: true,
-    onPaginate: (args: EuiBasicTableOnChange) => ({ pageNumber: args.page.index }),
-    openDeleteEngineModal: (engine) => ({ engine }),
-    openEngineCreate: true,
-    setSearchQuery: (searchQuery: string) => ({ searchQuery }),
-    setIsFirstRequest: true,
-  },
+  listeners: ({ actions, values }) => ({
+    deleteSuccess: () => {
+      actions.closeDeleteEngineModal();
+      actions.fetchEngines();
+    },
+    fetchEngines: async () => {
+      actions.makeRequest(values.parameters);
+    },
+  }),
+
   path: ['enterprise_search', 'content', 'engine_list_logic'],
+
   reducers: ({}) => ({
     createEngineFlyoutOpen: [
       false,
@@ -158,6 +169,11 @@ export const EnginesListLogic = kea<MakeLogicType<EngineListValues, EnginesListA
   }),
   selectors: ({ selectors }) => ({
     deleteModalEngineName: [() => [selectors.deleteModalEngine], (engine) => engine?.name ?? ''],
+    hasNoEngines: [
+      () => [selectors.data, selectors.results],
+      (data: EngineListValues['data'], results: EngineListValues['results']) =>
+        (data?.params?.from === 0 && results.length === 0 && !data?.params?.q) ?? false,
+    ],
 
     isDeleteLoading: [
       () => [selectors.deleteStatus],
@@ -168,22 +184,7 @@ export const EnginesListLogic = kea<MakeLogicType<EngineListValues, EnginesListA
       (status: EngineListValues['status'], isFirstRequest: EngineListValues['isFirstRequest']) =>
         [Status.LOADING, Status.IDLE].includes(status) && isFirstRequest,
     ],
-    results: [() => [selectors.data], (data) => data?.results ?? []],
-
-    hasNoEngines: [
-      () => [selectors.data, selectors.results],
-      (data: EngineListValues['data'], results: EngineListValues['results']) =>
-        (data?.params?.from === 0 && results.length === 0 && !data?.params?.q) ?? false,
-    ],
     meta: [() => [selectors.parameters], (parameters) => parameters.meta],
-  }),
-  listeners: ({ actions, values }) => ({
-    deleteSuccess: () => {
-      actions.closeDeleteEngineModal();
-      actions.fetchEngines();
-    },
-    fetchEngines: async () => {
-      actions.makeRequest(values.parameters);
-    },
+    results: [() => [selectors.data], (data) => data?.results ?? []],
   }),
 });

x-pack/plugins/enterprise_search/server/lib/engines/fetch_indices_stats.test.ts

@@ -0,0 +1,95 @@
+/*
+ * 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.
+ */
+import { IScopedClusterClient } from '@kbn/core/server';
+
+import { fetchIndicesStats } from './fetch_indices_stats';
+
+describe('fetchIndicesStats lib function', () => {
+  const mockClient = {
+    asCurrentUser: {
+      indices: {
+        stats: jest.fn(),
+      },
+    },
+    asInternalUser: {},
+  };
+  const indices = ['test-index-name-1', 'test-index-name-2', 'test-index-name-3'];
+  const indicesStats = {
+    indices: {
+      'test-index-name-1': {
+        health: 'GREEN',
+        primaries: { docs: [{}] },
+        status: 'open',
+        total: {
+          docs: {
+            count: 200,
+            deleted: 0,
+          },
+        },
+        uuid: 'YOLLiZ_mSRiDYDk0DJ-p8B',
+      },
+      'test-index-name-2': {
+        health: 'YELLOW',
+        primaries: { docs: [{}] },
+        status: 'closed',
+        total: {
+          docs: {
+            count: 0,
+            deleted: 0,
+          },
+        },
+        uuid: 'QOLLiZ_mGRiDYD30D2-p8B',
+      },
+      'test-index-name-3': {
+        health: 'RED',
+        primaries: { docs: [{}] },
+        status: 'open',
+        total: {
+          docs: {
+            count: 150,
+            deleted: 0,
+          },
+        },
+        uuid: 'QYLLiZ_fGRiDYD3082-e7',
+      },
+    },
+  };
+  const fetchIndicesStatsResponse = [
+    {
+      count: 200,
+      health: 'GREEN',
+      name: 'test-index-name-1',
+    },
+    {
+      count: 0,
+      health: 'YELLOW',
+      name: 'test-index-name-2',
+    },
+    {
+      count: 150,
+      health: 'RED',
+      name: 'test-index-name-3',
+    },
+  ];
+
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  it('should return hydrated indices', async () => {
+    mockClient.asCurrentUser.indices.stats.mockImplementationOnce(() => indicesStats);
+
+    await expect(
+      fetchIndicesStats(mockClient as unknown as IScopedClusterClient, indices)
+    ).resolves.toEqual(fetchIndicesStatsResponse);
+
+    expect(mockClient.asCurrentUser.indices.stats).toHaveBeenCalledWith({
+      index: indices,
+      metric: ['docs'],
+    });
+  });
+});

x-pack/plugins/enterprise_search/server/lib/engines/fetch_indices_stats.ts

@@ -0,0 +1,29 @@
+/*
+ * 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.
+ */
+
+import { IScopedClusterClient } from '@kbn/core-elasticsearch-server/src/client/scoped_cluster_client';
+
+import { EnterpriseSearchEngineIndex } from '../../../common/types/engines';
+
+export const fetchIndicesStats = async (client: IScopedClusterClient, indices: string[]) => {
+  const { indices: indicesStats = {} } = await client.asCurrentUser.indices.stats({
+    index: indices,
+    metric: ['docs'],
+  });
+
+  const indicesWithStats = indices.map((indexName: string) => {
+    const indexStats = indicesStats[indexName];
+    const hydratedIndex: EnterpriseSearchEngineIndex = {
+      count: indexStats?.total?.docs?.count ?? 0,
+      health: indexStats?.health ?? 'unknown',
+      name: indexName,
+    };
+    return hydratedIndex;
+  });
+
+  return indicesWithStats;
+};

x-pack/plugins/enterprise_search/server/routes/enterprise_search/engines.test.ts

@@ -10,9 +10,12 @@ import { mockDependencies, MockRouter } from '../../__mocks__';
 jest.mock('../../lib/engines/field_capabilities', () => ({
   fetchEngineFieldCapabilities: jest.fn(),
 }));
-
+jest.mock('../../lib/engines/fetch_indices_stats', () => ({
+  fetchIndicesStats: jest.fn(),
+}));
 import { RequestHandlerContext } from '@kbn/core/server';
 
+import { fetchIndicesStats } from '../../lib/engines/fetch_indices_stats';
 import { fetchEngineFieldCapabilities } from '../../lib/engines/field_capabilities';
 
 import { registerEnginesRoutes } from './engines';
@@ -115,6 +118,22 @@ describe('engines routes', () => {
         method: 'GET',
         path: '/_application/search_application/engine-name',
       });
+      const mock = jest.fn();
+
+      const fetchIndicesStatsResponse = [
+        { count: 5, health: 'green', name: 'test-index-name-1' },
+        { count: 10, health: 'yellow', name: 'test-index-name-2' },
+        { count: 0, health: 'red', name: 'test-index-name-3' },
+      ];
+      const engineResult = {
+        indices: mock(['test-index-name-1', 'test-index-name-2', 'test-index-name-3']),
+        name: 'test-engine-1',
+        updated_at_millis: 1679847286355,
+      };
+
+      (fetchIndicesStats as jest.Mock).mockResolvedValueOnce(fetchIndicesStatsResponse);
+      expect(fetchIndicesStats).toHaveBeenCalledWith(mockClient, engineResult.indices);
+
       expect(mockRouter.response.ok).toHaveBeenCalledWith({
         body: {},
       });

x-pack/plugins/enterprise_search/server/routes/enterprise_search/engines.ts

@@ -14,6 +14,7 @@ import {
 } from '../../../common/types/engines';
 import { ErrorCode } from '../../../common/types/error_codes';
 import { createApiKey } from '../../lib/engines/create_api_key';
+import { fetchIndicesStats } from '../../lib/engines/fetch_indices_stats';
 
 import { fetchEngineFieldCapabilities } from '../../lib/engines/field_capabilities';
 import { RouteDependencies } from '../../plugin';
@@ -63,7 +64,9 @@ export function registerEnginesRoutes({ log, router }: RouteDependencies) {
         method: 'GET',
         path: `/_application/search_application/${request.params.engine_name}`,
       });
-      return response.ok({ body: engine });
+      const indicesStats = await fetchIndicesStats(client, engine.indices);
+
+      return response.ok({ body: { ...engine, indices: indicesStats } });
     })
   );