From 25db1df1a3f399f1e7537ff9d186c152eca37223 Mon Sep 17 00:00:00 2001
From: Chris Cowan <chris@chriscowan.us>
Date: Tue, 29 Jun 2021 17:07:56 -0700
Subject: [PATCH] [Monitoring] Migrated legacy Elasticsearch client for 8.0
 (#101850)

---
 .../server/es_client/instantiate_client.ts    |   6 +-
 .../collectors/get_usage_collector.test.ts    |  19 +-
 .../collectors/get_usage_collector.ts         |  16 +-
 .../kibana_monitoring/collectors/index.ts     |   6 +-
 .../collectors/lib/fetch_es_usage.test.ts     | 110 ++++++------
 .../collectors/lib/fetch_es_usage.ts          |  34 +---
 .../collectors/lib/fetch_license_type.test.ts |  41 +++--
 .../collectors/lib/fetch_license_type.ts      |  11 +-
 .../lib/fetch_stack_product_usage.test.ts     |  99 +++++++----
 .../lib/fetch_stack_product_usage.ts          |  14 +-
 .../lib/get_stack_products_usage.test.ts      |  15 +-
 .../lib/get_stack_products_usage.ts           |   6 +-
 .../alerts/disable_watcher_cluster_alerts.ts  |  17 +-
 .../lib/alerts/fetch_ccr_read_exceptions.ts   |   2 +-
 .../server/lib/alerts/fetch_cluster_health.ts |   2 +-
 .../server/lib/alerts/fetch_clusters.ts       |   4 +-
 .../alerts/fetch_cpu_usage_node_stats.test.ts |   2 +-
 .../lib/alerts/fetch_cpu_usage_node_stats.ts  |   3 +-
 .../lib/alerts/fetch_disk_usage_node_stats.ts |   2 +-
 .../alerts/fetch_elasticsearch_versions.ts    |   2 +-
 .../lib/alerts/fetch_index_shard_size.ts      |   2 +-
 .../lib/alerts/fetch_kibana_versions.ts       |   2 +-
 .../server/lib/alerts/fetch_licenses.ts       |   2 +-
 .../lib/alerts/fetch_logstash_versions.ts     |   2 +-
 .../alerts/fetch_memory_usage_node_stats.ts   |   2 +-
 .../alerts/fetch_missing_monitoring_data.ts   |   2 +-
 .../alerts/fetch_nodes_from_cluster_stats.ts  |   2 +-
 .../fetch_thread_pool_rejections_stats.ts     |   2 +-
 .../server/lib/apm/_get_time_of_last_event.ts |   2 +-
 .../monitoring/server/lib/apm/get_apm_info.ts |   4 +-
 .../monitoring/server/lib/apm/get_apms.ts     |   4 +-
 .../server/lib/apm/get_apms_for_clusters.js   |   4 +-
 .../monitoring/server/lib/apm/get_stats.js    |   4 +-
 .../server/lib/beats/get_beat_summary.ts      |   4 +-
 .../monitoring/server/lib/beats/get_beats.ts  |   4 +-
 .../lib/beats/get_beats_for_clusters.js       |   4 +-
 .../server/lib/beats/get_latest_stats.js      |   4 +-
 .../monitoring/server/lib/beats/get_stats.js  |   4 +-
 .../lib/cluster/flag_supported_clusters.ts    |   4 +-
 .../server/lib/cluster/get_cluster_license.ts |   4 +-
 .../server/lib/cluster/get_clusters_state.ts  |   4 +-
 .../server/lib/cluster/get_clusters_stats.ts  |   4 +-
 .../server/lib/details/get_series.js          |   2 +-
 .../server/lib/elasticsearch/ccr.ts           |   4 +-
 .../lib/elasticsearch/get_last_recovery.ts    |   2 +-
 .../server/lib/elasticsearch/get_ml_jobs.ts   |   8 +-
 .../indices/get_index_summary.ts              |   2 +-
 .../lib/elasticsearch/indices/get_indices.ts  |   4 +-
 .../elasticsearch/nodes/get_node_summary.ts   |   2 +-
 .../nodes/get_nodes/get_node_ids.js           |   4 +-
 .../nodes/get_nodes/get_nodes.ts              |   4 +-
 .../get_indices_unassigned_shard_stats.ts     |   2 +-
 .../shards/get_nodes_shard_count.ts           |   2 +-
 .../shards/get_shard_allocation.ts            |   2 +-
 .../elasticsearch/shards/get_shard_stats.ts   |   2 +-
 .../elasticsearch/verify_monitoring_auth.js   |   2 +-
 .../lib/elasticsearch_settings/cluster.js     |  11 +-
 .../server/lib/kibana/get_kibana_info.ts      |   4 +-
 .../server/lib/kibana/get_kibanas.ts          |   2 +-
 .../lib/kibana/get_kibanas_for_clusters.js    |   2 +-
 .../server/lib/logs/get_log_types.ts          |   4 +-
 .../monitoring/server/lib/logs/get_logs.ts    |   4 +-
 .../lib/logstash/get_logstash_for_clusters.js |   2 +-
 .../server/lib/logstash/get_node_info.ts      |   4 +-
 .../server/lib/logstash/get_nodes.ts          |   2 +-
 .../server/lib/logstash/get_pipeline_ids.js   |   4 +-
 .../logstash/get_pipeline_state_document.ts   |   2 +-
 .../get_pipeline_stats_aggregation.js         |   4 +-
 .../lib/logstash/get_pipeline_versions.js     |   2 +-
 .../get_pipeline_vertex_stats_aggregation.js  |   4 +-
 .../setup/collection/get_collection_status.js |   8 +-
 .../monitoring/server/license_service.ts      |  14 +-
 x-pack/plugins/monitoring/server/plugin.ts    | 162 ++++++++++--------
 .../server/routes/api/v1/alerts/enable.ts     |   2 +-
 .../server/routes/api/v1/elasticsearch/ccr.ts |   2 +-
 .../routes/api/v1/elasticsearch/ccr_shard.ts  |   2 +-
 .../elasticsearch_settings/check/cluster.js   |   1 +
 .../check/internal_monitoring.ts              |   9 +-
 .../monitoring/server/static_globals.ts       |  71 ++++++--
 .../get_all_stats.test.ts                     |  25 ++-
 .../telemetry_collection/get_all_stats.ts     |   4 +-
 .../get_beats_stats.test.ts                   |  24 +--
 .../telemetry_collection/get_beats_stats.ts   |  23 +--
 .../get_cluster_uuids.test.ts                 |  33 ++--
 .../telemetry_collection/get_cluster_uuids.ts |  18 +-
 .../telemetry_collection/get_es_stats.test.ts |  22 +--
 .../telemetry_collection/get_es_stats.ts      |  18 +-
 .../get_high_level_stats.test.ts              |  20 ++-
 .../get_high_level_stats.ts                   |  27 +--
 .../telemetry_collection/get_kibana_stats.ts  |   4 +-
 .../telemetry_collection/get_licenses.test.ts |  20 ++-
 .../telemetry_collection/get_licenses.ts      |  18 +-
 .../get_logstash_stats.test.ts                |  45 +++--
 .../get_logstash_stats.ts                     |  48 +++---
 ...egister_monitoring_telemetry_collection.ts |  10 +-
 x-pack/plugins/monitoring/server/types.ts     |   7 +-
 96 files changed, 685 insertions(+), 526 deletions(-)

diff --git a/x-pack/plugins/monitoring/server/es_client/instantiate_client.ts b/x-pack/plugins/monitoring/server/es_client/instantiate_client.ts
index a32943dc10272a..58da336a5447dc 100644
--- a/x-pack/plugins/monitoring/server/es_client/instantiate_client.ts
+++ b/x-pack/plugins/monitoring/server/es_client/instantiate_client.ts
@@ -6,7 +6,7 @@
  */
 
 import { ConfigOptions } from 'elasticsearch';
-import { Logger, ILegacyCustomClusterClient } from 'kibana/server';
+import { Logger, ICustomClusterClient, ElasticsearchClientConfig } from 'kibana/server';
 // @ts-ignore
 import { monitoringBulk } from '../kibana_monitoring/lib/monitoring_bulk';
 import { monitoringEndpointDisableWatches } from './monitoring_endpoint_disable_watches';
@@ -25,8 +25,8 @@ export function instantiateClient(
   log: Logger,
   createClient: (
     type: string,
-    clientConfig?: Partial<ESClusterConfig>
-  ) => ILegacyCustomClusterClient
+    clientConfig?: Partial<ElasticsearchClientConfig> | undefined
+  ) => ICustomClusterClient
 ) {
   const isMonitoringCluster = hasMonitoringCluster(elasticsearchConfig);
   const cluster = createClient('monitoring', {
diff --git a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/get_usage_collector.test.ts b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/get_usage_collector.test.ts
index 03a3659b49ce19..9c72c1f8d3841b 100644
--- a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/get_usage_collector.test.ts
+++ b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/get_usage_collector.test.ts
@@ -6,11 +6,11 @@
  */
 
 import { getMonitoringUsageCollector } from './get_usage_collector';
-import { fetchClustersLegacy } from '../../lib/alerts/fetch_clusters';
+import { fetchClusters } from '../../lib/alerts/fetch_clusters';
 import { elasticsearchServiceMock } from '../../../../../../src/core/server/mocks';
 
 jest.mock('../../lib/alerts/fetch_clusters', () => ({
-  fetchClustersLegacy: jest.fn().mockImplementation(() => {
+  fetchClusters: jest.fn().mockImplementation(() => {
     return [
       {
         clusterUuid: '1abc',
@@ -59,7 +59,8 @@ jest.mock('./lib/fetch_license_type', () => ({
 }));
 
 describe('getMonitoringUsageCollector', () => {
-  const esClient = elasticsearchServiceMock.createLegacyClusterClient();
+  const esClient = elasticsearchServiceMock.createClusterClient();
+  const getEsClient = () => esClient;
   const config: any = {
     ui: {
       ccs: {
@@ -72,7 +73,7 @@ describe('getMonitoringUsageCollector', () => {
     const usageCollection: any = {
       makeUsageCollector: jest.fn(),
     };
-    await getMonitoringUsageCollector(usageCollection, config, esClient);
+    getMonitoringUsageCollector(usageCollection, config, getEsClient);
 
     const mock = (usageCollection.makeUsageCollector as jest.Mock).mock;
 
@@ -122,7 +123,7 @@ describe('getMonitoringUsageCollector', () => {
       makeUsageCollector: jest.fn(),
     };
 
-    await getMonitoringUsageCollector(usageCollection, config, esClient);
+    getMonitoringUsageCollector(usageCollection, config, getEsClient);
     const mock = (usageCollection.makeUsageCollector as jest.Mock).mock;
     const args = mock.calls[0];
 
@@ -149,11 +150,11 @@ describe('getMonitoringUsageCollector', () => {
       makeUsageCollector: jest.fn(),
     };
 
-    await getMonitoringUsageCollector(usageCollection, config, esClient);
+    getMonitoringUsageCollector(usageCollection, config, getEsClient);
     const mock = (usageCollection.makeUsageCollector as jest.Mock).mock;
     const args = mock.calls[0];
 
-    (fetchClustersLegacy as jest.Mock).mockImplementation(() => {
+    (fetchClusters as jest.Mock).mockImplementation(() => {
       return [];
     });
 
@@ -169,11 +170,11 @@ describe('getMonitoringUsageCollector', () => {
       makeUsageCollector: jest.fn(),
     };
 
-    await getMonitoringUsageCollector(usageCollection, config, esClient);
+    getMonitoringUsageCollector(usageCollection, config, getEsClient);
     const mock = (usageCollection.makeUsageCollector as jest.Mock).mock;
     const args = mock.calls[0];
 
-    (fetchClustersLegacy as jest.Mock).mockImplementation(() => {
+    (fetchClusters as jest.Mock).mockImplementation(() => {
       return [];
     });
 
diff --git a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/get_usage_collector.ts b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/get_usage_collector.ts
index 6f638b6ff8f0e0..558a79e03dcb7a 100644
--- a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/get_usage_collector.ts
+++ b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/get_usage_collector.ts
@@ -6,20 +6,20 @@
  */
 
 import { UsageCollectionSetup } from 'src/plugins/usage_collection/server';
-import { ILegacyClusterClient } from 'src/core/server';
+import { IClusterClient } from 'src/core/server';
 import { MonitoringConfig } from '../../config';
-import { fetchAvailableCcsLegacy } from '../../lib/alerts/fetch_available_ccs';
+import { fetchAvailableCcs } from '../../lib/alerts/fetch_available_ccs';
 import { getStackProductsUsage } from './lib/get_stack_products_usage';
 import { fetchLicenseType } from './lib/fetch_license_type';
 import { MonitoringUsage, StackProductUsage, MonitoringClusterStackProductUsage } from './types';
 import { INDEX_PATTERN_ELASTICSEARCH } from '../../../common/constants';
 import { getCcsIndexPattern } from '../../lib/alerts/get_ccs_index_pattern';
-import { fetchClustersLegacy } from '../../lib/alerts/fetch_clusters';
+import { fetchClusters } from '../../lib/alerts/fetch_clusters';
 
 export function getMonitoringUsageCollector(
   usageCollection: UsageCollectionSetup,
   config: MonitoringConfig,
-  legacyEsClient: ILegacyClusterClient
+  getClient: () => IClusterClient
 ) {
   return usageCollection.makeUsageCollector<MonitoringUsage, true>({
     type: 'monitoring',
@@ -103,12 +103,12 @@ export function getMonitoringUsageCollector(
     },
     fetch: async ({ kibanaRequest }) => {
       const callCluster = kibanaRequest
-        ? legacyEsClient.asScoped(kibanaRequest).callAsCurrentUser
-        : legacyEsClient.callAsInternalUser;
+        ? getClient().asScoped(kibanaRequest).asCurrentUser
+        : getClient().asInternalUser;
       const usageClusters: MonitoringClusterStackProductUsage[] = [];
-      const availableCcs = config.ui.ccs.enabled ? await fetchAvailableCcsLegacy(callCluster) : [];
+      const availableCcs = config.ui.ccs.enabled ? await fetchAvailableCcs(callCluster) : [];
       const elasticsearchIndex = getCcsIndexPattern(INDEX_PATTERN_ELASTICSEARCH, availableCcs);
-      const clusters = await fetchClustersLegacy(callCluster, elasticsearchIndex);
+      const clusters = await fetchClusters(callCluster, elasticsearchIndex);
       for (const cluster of clusters) {
         const license = await fetchLicenseType(callCluster, availableCcs, cluster.clusterUuid);
         const stackProducts = await getStackProductsUsage(
diff --git a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/index.ts b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/index.ts
index 5549b7aa968d0b..06d47f00447286 100644
--- a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/index.ts
+++ b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/index.ts
@@ -5,7 +5,7 @@
  * 2.0.
  */
 
-import { ILegacyClusterClient } from 'src/core/server';
+import { IClusterClient } from 'src/core/server';
 import { UsageCollectionSetup } from 'src/plugins/usage_collection/server';
 import { getSettingsCollector } from './get_settings_collector';
 import { getMonitoringUsageCollector } from './get_usage_collector';
@@ -16,10 +16,10 @@ export { KibanaSettingsCollector, getKibanaSettings } from './get_settings_colle
 export function registerCollectors(
   usageCollection: UsageCollectionSetup,
   config: MonitoringConfig,
-  legacyEsClient: ILegacyClusterClient
+  getClient: () => IClusterClient
 ) {
   usageCollection.registerCollector(getSettingsCollector(usageCollection, config));
   usageCollection.registerCollector(
-    getMonitoringUsageCollector(usageCollection, config, legacyEsClient)
+    getMonitoringUsageCollector(usageCollection, config, getClient)
   );
 }
diff --git a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_es_usage.test.ts b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_es_usage.test.ts
index 6d01dbc120be37..b7d616a5a3cc77 100644
--- a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_es_usage.test.ts
+++ b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_es_usage.test.ts
@@ -5,41 +5,45 @@
  * 2.0.
  */
 
+import { ElasticsearchClient } from 'kibana/server';
 import { fetchESUsage } from './fetch_es_usage';
 
 describe('fetchESUsage', () => {
   const clusterUuid = '1abcde2';
   const index = '.monitoring-es-*';
-  const callCluster = jest.fn().mockImplementation(() => ({
-    hits: {
-      hits: [
-        {
-          _source: {
-            cluster_stats: {
-              nodes: {
-                count: {
-                  total: 10,
+  const callCluster = ({
+    search: jest.fn().mockImplementation(() => ({
+      body: {
+        hits: {
+          hits: [
+            {
+              _source: {
+                cluster_stats: {
+                  nodes: {
+                    count: {
+                      total: 10,
+                    },
+                  },
                 },
               },
             },
-          },
+          ],
         },
-      ],
-    },
-    aggregations: {
-      indices: {
-        buckets: [
-          {
-            key: '.monitoring-es-2',
+        aggregations: {
+          indices: {
+            buckets: [
+              {
+                key: '.monitoring-es-2',
+              },
+            ],
           },
-        ],
+        },
       },
-    },
-  }));
-  const config: any = {};
+    })),
+  } as unknown) as ElasticsearchClient;
 
   it('should return usage data for Elasticsearch', async () => {
-    const result = await fetchESUsage(config, callCluster, clusterUuid, index);
+    const result = await fetchESUsage(callCluster, clusterUuid, index);
     expect(result).toStrictEqual({
       count: 10,
       enabled: true,
@@ -48,33 +52,37 @@ describe('fetchESUsage', () => {
   });
 
   it('should handle some indices coming from Metricbeat', async () => {
-    const customCallCluster = jest.fn().mockImplementation(() => ({
-      hits: {
-        hits: [
-          {
-            _source: {
-              cluster_stats: {
-                nodes: {
-                  count: {
-                    total: 10,
+    const customCallCluster = ({
+      search: jest.fn().mockImplementation(() => ({
+        body: {
+          hits: {
+            hits: [
+              {
+                _source: {
+                  cluster_stats: {
+                    nodes: {
+                      count: {
+                        total: 10,
+                      },
+                    },
                   },
                 },
               },
-            },
+            ],
           },
-        ],
-      },
-      aggregations: {
-        indices: {
-          buckets: [
-            {
-              key: '.monitoring-es-mb-2',
+          aggregations: {
+            indices: {
+              buckets: [
+                {
+                  key: '.monitoring-es-mb-2',
+                },
+              ],
             },
-          ],
+          },
         },
-      },
-    }));
-    const result = await fetchESUsage(config, customCallCluster, clusterUuid, index);
+      })),
+    } as unknown) as ElasticsearchClient;
+    const result = await fetchESUsage(customCallCluster, clusterUuid, index);
     expect(result).toStrictEqual({
       count: 10,
       enabled: true,
@@ -83,12 +91,16 @@ describe('fetchESUsage', () => {
   });
 
   it('should handle no monitoring data', async () => {
-    const customCallCluster = jest.fn().mockImplementation(() => ({
-      hits: {
-        hits: [],
-      },
-    }));
-    const result = await fetchESUsage(config, customCallCluster, clusterUuid, index);
+    const customCallCluster = ({
+      search: jest.fn().mockImplementation(() => ({
+        body: {
+          hits: {
+            hits: [],
+          },
+        },
+      })),
+    } as unknown) as ElasticsearchClient;
+    const result = await fetchESUsage(customCallCluster, clusterUuid, index);
     expect(result).toStrictEqual({
       count: 0,
       enabled: false,
diff --git a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_es_usage.ts b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_es_usage.ts
index b96c119bf5ab8d..1fb2ba70f2ab11 100644
--- a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_es_usage.ts
+++ b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_es_usage.ts
@@ -5,30 +5,15 @@
  * 2.0.
  */
 
-import { LegacyAPICaller } from 'src/core/server';
+import { ElasticsearchClient } from 'src/core/server';
 import { get } from 'lodash';
-import { MonitoringConfig } from '../../../config';
+import { estypes } from '@elastic/elasticsearch';
 import { StackProductUsage } from '../types';
 
-interface ESResponse {
-  hits: {
-    hits: ESResponseHits[];
-  };
-  aggregations: {
-    indices: {
-      buckets: ESIndicesBucket;
-    };
-  };
-}
-
 interface ESIndicesBucket {
   key: string;
 }
 
-interface ESResponseHits {
-  _source: ClusterStats;
-}
-
 interface ClusterStats {
   cluster_stats: {
     nodes: {
@@ -41,16 +26,15 @@ interface ClusterStats {
 }
 
 export async function fetchESUsage(
-  config: MonitoringConfig,
-  callCluster: LegacyAPICaller,
+  callCluster: ElasticsearchClient,
   clusterUuid: string,
   index: string
 ): Promise<StackProductUsage> {
-  const params = {
+  const params: estypes.SearchRequest = {
     index,
     size: 1,
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       'hits.hits._source.cluster_stats.nodes.count.total',
       'aggregations.indices.buckets',
     ],
@@ -101,8 +85,8 @@ export async function fetchESUsage(
     },
   };
 
-  const response = await callCluster('search', params);
-  const esResponse = response as ESResponse;
+  const { body: response } = await callCluster.search(params);
+  const esResponse = response as estypes.SearchResponse<ClusterStats>;
   if (esResponse.hits.hits.length === 0) {
     return {
       count: 0,
@@ -112,7 +96,7 @@ export async function fetchESUsage(
   }
 
   const hit = esResponse.hits.hits[0]._source;
-  const count = hit.cluster_stats.nodes.count.total;
+  const count = hit?.cluster_stats.nodes.count.total || 0;
   const buckets = get(esResponse, 'aggregations.indices.buckets', []) as ESIndicesBucket[];
   const metricbeatUsed = Boolean(buckets.find((indexBucket) => indexBucket.key.includes('-mb-')));
 
diff --git a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_license_type.test.ts b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_license_type.test.ts
index b5c3293af40209..e4d801cfac0c3a 100644
--- a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_license_type.test.ts
+++ b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_license_type.test.ts
@@ -5,24 +5,29 @@
  * 2.0.
  */
 
+import { ElasticsearchClient } from 'kibana/server';
 import { fetchLicenseType } from './fetch_license_type';
 
 describe('fetchLicenseType', () => {
   const clusterUuid = '1abcde2';
   const availableCcs: string[] = [];
-  const callCluster = jest.fn().mockImplementation(() => ({
-    hits: {
-      hits: [
-        {
-          _source: {
-            license: {
-              type: 'trial',
+  const callCluster = ({
+    search: jest.fn().mockImplementation(() => ({
+      body: {
+        hits: {
+          hits: [
+            {
+              _source: {
+                license: {
+                  type: 'trial',
+                },
+              },
             },
-          },
+          ],
         },
-      ],
-    },
-  }));
+      },
+    })),
+  } as unknown) as ElasticsearchClient;
 
   it('should get the license type', async () => {
     const result = await fetchLicenseType(callCluster, availableCcs, clusterUuid);
@@ -30,11 +35,15 @@ describe('fetchLicenseType', () => {
   });
 
   it('should handle no license data', async () => {
-    const customCallCluster = jest.fn().mockImplementation(() => ({
-      hits: {
-        hits: [],
-      },
-    }));
+    const customCallCluster = ({
+      search: jest.fn().mockImplementation(() => ({
+        body: {
+          hits: {
+            hits: [],
+          },
+        },
+      })),
+    } as unknown) as ElasticsearchClient;
     const result = await fetchLicenseType(customCallCluster, availableCcs, clusterUuid);
     expect(result).toStrictEqual(null);
   });
diff --git a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_license_type.ts b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_license_type.ts
index eed177a6647f20..f42623ff851ce7 100644
--- a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_license_type.ts
+++ b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_license_type.ts
@@ -6,12 +6,13 @@
  */
 
 import { get } from 'lodash';
-import { LegacyAPICaller } from 'src/core/server';
+import { ElasticsearchClient } from 'src/core/server';
+import { estypes } from '@elastic/elasticsearch';
 import { INDEX_PATTERN_ELASTICSEARCH } from '../../../../common/constants';
 import { getCcsIndexPattern } from '../../../lib/alerts/get_ccs_index_pattern';
 
 export async function fetchLicenseType(
-  callCluster: LegacyAPICaller,
+  client: ElasticsearchClient,
   availableCcs: string[],
   clusterUuid: string
 ) {
@@ -19,9 +20,9 @@ export async function fetchLicenseType(
   if (availableCcs) {
     index = getCcsIndexPattern(index, availableCcs);
   }
-  const params = {
+  const params: estypes.SearchRequest = {
     index,
-    filterPath: ['hits.hits._source.license'],
+    filter_path: ['hits.hits._source.license'],
     body: {
       size: 1,
       sort: [
@@ -54,6 +55,6 @@ export async function fetchLicenseType(
       },
     },
   };
-  const response = await callCluster('search', params);
+  const { body: response } = await client.search(params);
   return get(response, 'hits.hits[0]._source.license.type', null);
 }
diff --git a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_stack_product_usage.test.ts b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_stack_product_usage.test.ts
index 4a2f1abdc96ef2..a8650c375a0dfc 100644
--- a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_stack_product_usage.test.ts
+++ b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_stack_product_usage.test.ts
@@ -5,6 +5,7 @@
  * 2.0.
  */
 
+import { ElasticsearchClient } from 'kibana/server';
 import { fetchStackProductUsage } from './fetch_stack_product_usage';
 
 describe('fetchStackProductUsage', () => {
@@ -16,7 +17,27 @@ describe('fetchStackProductUsage', () => {
   };
 
   it('should use appropiate query parameters', async () => {
-    const callCluster = jest.fn();
+    const searchMock = jest.fn().mockImplementation(() => ({
+      body: {
+        aggregations: {
+          uuids: {
+            buckets: [
+              {
+                key: 'sadfsdf',
+                indices: {
+                  buckets: [
+                    {
+                      key: '.monitoring-kibana-8',
+                    },
+                  ],
+                },
+              },
+            ],
+          },
+        },
+      },
+    }));
+    const callCluster = ({ search: searchMock } as unknown) as ElasticsearchClient;
     await fetchStackProductUsage(
       config,
       callCluster,
@@ -34,7 +55,7 @@ describe('fetchStackProductUsage', () => {
         },
       ]
     );
-    const params = callCluster.mock.calls[0][1];
+    const params = searchMock.mock.calls[0][0];
     expect(params.body.query.bool.must[0].term.type.value).toBe('kibana_stats');
     expect(params.body.query.bool.must[1].term.cluster_uuid.value).toBe(clusterUuid);
     expect(params.body.query.bool.must[2].range.timestamp.gte).toBe('now-1h');
@@ -42,24 +63,28 @@ describe('fetchStackProductUsage', () => {
   });
 
   it('should get the usage data', async () => {
-    const callCluster = jest.fn().mockImplementation(() => ({
-      aggregations: {
-        uuids: {
-          buckets: [
-            {
-              key: 'sadfsdf',
-              indices: {
-                buckets: [
-                  {
-                    key: '.monitoring-kibana-8',
+    const callCluster = ({
+      search: jest.fn().mockImplementation(() => ({
+        body: {
+          aggregations: {
+            uuids: {
+              buckets: [
+                {
+                  key: 'sadfsdf',
+                  indices: {
+                    buckets: [
+                      {
+                        key: '.monitoring-kibana-8',
+                      },
+                    ],
                   },
-                ],
-              },
+                },
+              ],
             },
-          ],
+          },
         },
-      },
-    }));
+      })),
+    } as unknown) as ElasticsearchClient;
 
     const result = await fetchStackProductUsage(
       config,
@@ -78,27 +103,31 @@ describe('fetchStackProductUsage', () => {
   });
 
   it('should handle both collection types', async () => {
-    const callCluster = jest.fn().mockImplementation(() => ({
-      aggregations: {
-        uuids: {
-          buckets: [
-            {
-              key: 'sadfsdf',
-              indices: {
-                buckets: [
-                  {
-                    key: '.monitoring-kibana-8',
+    const callCluster = ({
+      search: jest.fn().mockImplementation(() => ({
+        body: {
+          aggregations: {
+            uuids: {
+              buckets: [
+                {
+                  key: 'sadfsdf',
+                  indices: {
+                    buckets: [
+                      {
+                        key: '.monitoring-kibana-8',
+                      },
+                      {
+                        key: '.monitoring-kibana-mb-8',
+                      },
+                    ],
                   },
-                  {
-                    key: '.monitoring-kibana-mb-8',
-                  },
-                ],
-              },
+                },
+              ],
             },
-          ],
+          },
         },
-      },
-    }));
+      })),
+    } as unknown) as ElasticsearchClient;
 
     const result = await fetchStackProductUsage(
       config,
diff --git a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_stack_product_usage.ts b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_stack_product_usage.ts
index 2160e159ad1008..527ed503c8fafc 100644
--- a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_stack_product_usage.ts
+++ b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/fetch_stack_product_usage.ts
@@ -6,7 +6,8 @@
  */
 
 import { get } from 'lodash';
-import { LegacyAPICaller } from 'src/core/server';
+import { ElasticsearchClient } from 'src/core/server';
+import { estypes } from '@elastic/elasticsearch';
 import { MonitoringConfig } from '../../../config';
 // @ts-ignore
 import { prefixIndexPattern } from '../../../lib/ccs_utils';
@@ -33,7 +34,7 @@ interface KeyBucket {
 
 export async function fetchStackProductUsage(
   config: MonitoringConfig,
-  callCluster: LegacyAPICaller,
+  callCluster: ElasticsearchClient,
   clusterUuid: string,
   index: string,
   type: string,
@@ -41,11 +42,11 @@ export async function fetchStackProductUsage(
   filters: any[] = []
 ): Promise<StackProductUsage> {
   const size = config.ui.max_bucket_size;
-  const params = {
+  const params: estypes.SearchRequest = {
     index,
     size: 0,
-    ignoreUnavailable: true,
-    filterPath: ['aggregations.uuids.buckets'],
+    ignore_unavailable: true,
+    filter_path: ['aggregations.uuids.buckets'],
     body: {
       query: {
         bool: {
@@ -94,7 +95,8 @@ export async function fetchStackProductUsage(
     },
   };
 
-  const response = (await callCluster('search', params)) as ESResponse;
+  const { body: responseBody } = await callCluster.search(params);
+  const response = responseBody as estypes.SearchResponse<ESResponse>;
   const uuidBuckets = get(response, 'aggregations.uuids.buckets', []) as UuidBucket[];
   const count = uuidBuckets.length;
   const metricbeatUsed = Boolean(
diff --git a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/get_stack_products_usage.test.ts b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/get_stack_products_usage.test.ts
index 8a3135ff832a98..928d7efcdd0d1c 100644
--- a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/get_stack_products_usage.test.ts
+++ b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/get_stack_products_usage.test.ts
@@ -5,6 +5,7 @@
  * 2.0.
  */
 
+import { ElasticsearchClient } from 'kibana/server';
 import { getStackProductsUsage } from './get_stack_products_usage';
 
 describe('getStackProductsUsage', () => {
@@ -15,11 +16,15 @@ describe('getStackProductsUsage', () => {
   };
   const clusterUuid = '1abcde2';
   const availableCcs: string[] = [];
-  const callCluster = jest.fn().mockImplementation(() => ({
-    hits: {
-      hits: [],
-    },
-  }));
+  const callCluster = ({
+    search: jest.fn().mockImplementation(() => ({
+      body: {
+        hits: {
+          hits: [],
+        },
+      },
+    })),
+  } as unknown) as ElasticsearchClient;
 
   it('should get all stack products', async () => {
     const result = await getStackProductsUsage(config, callCluster, availableCcs, clusterUuid);
diff --git a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/get_stack_products_usage.ts b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/get_stack_products_usage.ts
index 0fd214f2fa8557..7cce1b392112f9 100644
--- a/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/get_stack_products_usage.ts
+++ b/x-pack/plugins/monitoring/server/kibana_monitoring/collectors/lib/get_stack_products_usage.ts
@@ -5,7 +5,7 @@
  * 2.0.
  */
 
-import { LegacyAPICaller } from 'src/core/server';
+import { ElasticsearchClient } from 'src/core/server';
 import { MonitoringClusterStackProductUsage } from '../types';
 import { fetchESUsage } from './fetch_es_usage';
 import { MonitoringConfig } from '../../../config';
@@ -24,7 +24,7 @@ import { getCcsIndexPattern } from '../../../lib/alerts/get_ccs_index_pattern';
 
 export const getStackProductsUsage = async (
   config: MonitoringConfig,
-  callCluster: LegacyAPICaller,
+  callCluster: ElasticsearchClient,
   availableCcs: string[],
   clusterUuid: string
 ): Promise<
@@ -38,7 +38,7 @@ export const getStackProductsUsage = async (
   const logstashIndex = getCcsIndexPattern(INDEX_PATTERN_LOGSTASH, availableCcs);
   const beatsIndex = getCcsIndexPattern(INDEX_PATTERN_BEATS, availableCcs);
   const [elasticsearch, kibana, logstash, beats, apm] = await Promise.all([
-    fetchESUsage(config, callCluster, clusterUuid, elasticsearchIndex),
+    fetchESUsage(callCluster, clusterUuid, elasticsearchIndex),
     fetchStackProductUsage(
       config,
       callCluster,
diff --git a/x-pack/plugins/monitoring/server/lib/alerts/disable_watcher_cluster_alerts.ts b/x-pack/plugins/monitoring/server/lib/alerts/disable_watcher_cluster_alerts.ts
index dff828d05e2b60..e1dfb893869898 100644
--- a/x-pack/plugins/monitoring/server/lib/alerts/disable_watcher_cluster_alerts.ts
+++ b/x-pack/plugins/monitoring/server/lib/alerts/disable_watcher_cluster_alerts.ts
@@ -6,7 +6,7 @@
  */
 
 import { Logger } from 'kibana/server';
-import { LegacyAPICaller } from 'src/core/server';
+import { ElasticsearchClient } from 'src/core/server';
 
 interface DisableWatchesResponse {
   exporters: Array<
@@ -22,9 +22,13 @@ interface DisableWatchesResponse {
   >;
 }
 
-async function callMigrationApi(callCluster: LegacyAPICaller, logger: Logger) {
+async function callMigrationApi(callCluster: ElasticsearchClient, logger: Logger) {
   try {
-    return await callCluster('monitoring.disableWatches');
+    const { body: response } = await callCluster.transport.request({
+      method: 'post',
+      path: '/monitoring.disableWatches',
+    });
+    return response as DisableWatchesResponse;
   } catch (err) {
     logger.warn(
       `Unable to call migration api to disable cluster alert watches. Message=${err.message}`
@@ -33,8 +37,11 @@ async function callMigrationApi(callCluster: LegacyAPICaller, logger: Logger) {
   }
 }
 
-export async function disableWatcherClusterAlerts(callCluster: LegacyAPICaller, logger: Logger) {
-  const response: DisableWatchesResponse = await callMigrationApi(callCluster, logger);
+export async function disableWatcherClusterAlerts(
+  callCluster: ElasticsearchClient,
+  logger: Logger
+) {
+  const response: DisableWatchesResponse | undefined = await callMigrationApi(callCluster, logger);
   if (!response || response.exporters.length === 0) {
     return true;
   }
diff --git a/x-pack/plugins/monitoring/server/lib/alerts/fetch_ccr_read_exceptions.ts b/x-pack/plugins/monitoring/server/lib/alerts/fetch_ccr_read_exceptions.ts
index a96a7454ea744a..560751d1297d53 100644
--- a/x-pack/plugins/monitoring/server/lib/alerts/fetch_ccr_read_exceptions.ts
+++ b/x-pack/plugins/monitoring/server/lib/alerts/fetch_ccr_read_exceptions.ts
@@ -18,7 +18,7 @@ export async function fetchCCRReadExceptions(
 ): Promise<CCRReadExceptionsStats[]> {
   const params = {
     index,
-    filterPath: ['aggregations.remote_clusters.buckets'],
+    filter_path: ['aggregations.remote_clusters.buckets'],
     body: {
       size: 0,
       query: {
diff --git a/x-pack/plugins/monitoring/server/lib/alerts/fetch_cluster_health.ts b/x-pack/plugins/monitoring/server/lib/alerts/fetch_cluster_health.ts
index f622418c77910f..85bfbd9dbd0490 100644
--- a/x-pack/plugins/monitoring/server/lib/alerts/fetch_cluster_health.ts
+++ b/x-pack/plugins/monitoring/server/lib/alerts/fetch_cluster_health.ts
@@ -15,7 +15,7 @@ export async function fetchClusterHealth(
 ): Promise<AlertClusterHealth[]> {
   const params = {
     index,
-    filterPath: [
+    filter_path: [
       'hits.hits._source.cluster_state.status',
       'hits.hits._source.cluster_uuid',
       'hits.hits._index',
diff --git a/x-pack/plugins/monitoring/server/lib/alerts/fetch_clusters.ts b/x-pack/plugins/monitoring/server/lib/alerts/fetch_clusters.ts
index bbaea8d9f206e6..8b5803d588e12e 100644
--- a/x-pack/plugins/monitoring/server/lib/alerts/fetch_clusters.ts
+++ b/x-pack/plugins/monitoring/server/lib/alerts/fetch_clusters.ts
@@ -23,7 +23,7 @@ export async function fetchClusters(
 ): Promise<AlertCluster[]> {
   const params = {
     index,
-    filterPath: [
+    filter_path: [
       'hits.hits._source.cluster_settings.cluster.metadata.display_name',
       'hits.hits._source.cluster_uuid',
       'hits.hits._source.cluster_name',
@@ -70,7 +70,7 @@ export async function fetchClustersLegacy(
 ): Promise<AlertCluster[]> {
   const params = {
     index,
-    filterPath: [
+    filter_path: [
       'hits.hits._source.cluster_settings.cluster.metadata.display_name',
       'hits.hits._source.cluster_uuid',
       'hits.hits._source.cluster_name',
diff --git a/x-pack/plugins/monitoring/server/lib/alerts/fetch_cpu_usage_node_stats.test.ts b/x-pack/plugins/monitoring/server/lib/alerts/fetch_cpu_usage_node_stats.test.ts
index 9cb773c81923b1..90cd456f18037a 100644
--- a/x-pack/plugins/monitoring/server/lib/alerts/fetch_cpu_usage_node_stats.test.ts
+++ b/x-pack/plugins/monitoring/server/lib/alerts/fetch_cpu_usage_node_stats.test.ts
@@ -204,7 +204,7 @@ describe('fetchCpuUsageNodeStats', () => {
     await fetchCpuUsageNodeStats(esClient, clusters, index, startMs, endMs, size);
     expect(params).toStrictEqual({
       index: '.monitoring-es-*',
-      filterPath: ['aggregations'],
+      filter_path: ['aggregations'],
       body: {
         size: 0,
         query: {
diff --git a/x-pack/plugins/monitoring/server/lib/alerts/fetch_cpu_usage_node_stats.ts b/x-pack/plugins/monitoring/server/lib/alerts/fetch_cpu_usage_node_stats.ts
index 07ca3572ad6b3f..6f7d27916a7b1b 100644
--- a/x-pack/plugins/monitoring/server/lib/alerts/fetch_cpu_usage_node_stats.ts
+++ b/x-pack/plugins/monitoring/server/lib/alerts/fetch_cpu_usage_node_stats.ts
@@ -34,10 +34,9 @@ export async function fetchCpuUsageNodeStats(
   // Using pure MS didn't seem to work well with the date_histogram interval
   // but minutes does
   const intervalInMinutes = moment.duration(endMs - startMs).asMinutes();
-  const filterPath = ['aggregations'];
   const params = {
     index,
-    filterPath,
+    filter_path: ['aggregations'],
     body: {
       size: 0,
       query: {
diff --git a/x-pack/plugins/monitoring/server/lib/alerts/fetch_disk_usage_node_stats.ts b/x-pack/plugins/monitoring/server/lib/alerts/fetch_disk_usage_node_stats.ts
index 2e8b5c7478e152..70f05991d42291 100644
--- a/x-pack/plugins/monitoring/server/lib/alerts/fetch_disk_usage_node_stats.ts
+++ b/x-pack/plugins/monitoring/server/lib/alerts/fetch_disk_usage_node_stats.ts
@@ -19,7 +19,7 @@ export async function fetchDiskUsageNodeStats(
   const clustersIds = clusters.map((cluster) => cluster.clusterUuid);
   const params = {
     index,
-    filterPath: ['aggregations'],
+    filter_path: ['aggregations'],
     body: {
       size: 0,
       query: {
diff --git a/x-pack/plugins/monitoring/server/lib/alerts/fetch_elasticsearch_versions.ts b/x-pack/plugins/monitoring/server/lib/alerts/fetch_elasticsearch_versions.ts
index f25f1dbe594db9..f2f311ac870a51 100644
--- a/x-pack/plugins/monitoring/server/lib/alerts/fetch_elasticsearch_versions.ts
+++ b/x-pack/plugins/monitoring/server/lib/alerts/fetch_elasticsearch_versions.ts
@@ -16,7 +16,7 @@ export async function fetchElasticsearchVersions(
 ): Promise<AlertVersions[]> {
   const params = {
     index,
-    filterPath: [
+    filter_path: [
       'hits.hits._source.cluster_stats.nodes.versions',
       'hits.hits._index',
       'hits.hits._source.cluster_uuid',
diff --git a/x-pack/plugins/monitoring/server/lib/alerts/fetch_index_shard_size.ts b/x-pack/plugins/monitoring/server/lib/alerts/fetch_index_shard_size.ts
index 117894c0d823b5..7e7ea5e6bfdd22 100644
--- a/x-pack/plugins/monitoring/server/lib/alerts/fetch_index_shard_size.ts
+++ b/x-pack/plugins/monitoring/server/lib/alerts/fetch_index_shard_size.ts
@@ -39,7 +39,7 @@ export async function fetchIndexShardSize(
 ): Promise<IndexShardSizeStats[]> {
   const params = {
     index,
-    filterPath: ['aggregations.clusters.buckets'],
+    filter_path: ['aggregations.clusters.buckets'],
     body: {
       size: 0,
       query: {
diff --git a/x-pack/plugins/monitoring/server/lib/alerts/fetch_kibana_versions.ts b/x-pack/plugins/monitoring/server/lib/alerts/fetch_kibana_versions.ts
index cb2f201e2586ec..e57b45e2570fa1 100644
--- a/x-pack/plugins/monitoring/server/lib/alerts/fetch_kibana_versions.ts
+++ b/x-pack/plugins/monitoring/server/lib/alerts/fetch_kibana_versions.ts
@@ -20,7 +20,7 @@ export async function fetchKibanaVersions(
 ): Promise<AlertVersions[]> {
   const params = {
     index,
-    filterPath: ['aggregations'],
+    filter_path: ['aggregations'],
     body: {
       size: 0,
       query: {
diff --git a/x-pack/plugins/monitoring/server/lib/alerts/fetch_licenses.ts b/x-pack/plugins/monitoring/server/lib/alerts/fetch_licenses.ts
index 5178b6c4c53a71..38ff82cf298329 100644
--- a/x-pack/plugins/monitoring/server/lib/alerts/fetch_licenses.ts
+++ b/x-pack/plugins/monitoring/server/lib/alerts/fetch_licenses.ts
@@ -15,7 +15,7 @@ export async function fetchLicenses(
 ): Promise<AlertLicense[]> {
   const params = {
     index,
-    filterPath: [
+    filter_path: [
       'hits.hits._source.license.*',
       'hits.hits._source.cluster_uuid',
       'hits.hits._index',
diff --git a/x-pack/plugins/monitoring/server/lib/alerts/fetch_logstash_versions.ts b/x-pack/plugins/monitoring/server/lib/alerts/fetch_logstash_versions.ts
index 6fb54857d40e43..774ee2551ec073 100644
--- a/x-pack/plugins/monitoring/server/lib/alerts/fetch_logstash_versions.ts
+++ b/x-pack/plugins/monitoring/server/lib/alerts/fetch_logstash_versions.ts
@@ -20,7 +20,7 @@ export async function fetchLogstashVersions(
 ): Promise<AlertVersions[]> {
   const params = {
     index,
-    filterPath: ['aggregations'],
+    filter_path: ['aggregations'],
     body: {
       size: 0,
       query: {
diff --git a/x-pack/plugins/monitoring/server/lib/alerts/fetch_memory_usage_node_stats.ts b/x-pack/plugins/monitoring/server/lib/alerts/fetch_memory_usage_node_stats.ts
index 46bb9c794a6a69..f34a8dcff1db73 100644
--- a/x-pack/plugins/monitoring/server/lib/alerts/fetch_memory_usage_node_stats.ts
+++ b/x-pack/plugins/monitoring/server/lib/alerts/fetch_memory_usage_node_stats.ts
@@ -20,7 +20,7 @@ export async function fetchMemoryUsageNodeStats(
   const clustersIds = clusters.map((cluster) => cluster.clusterUuid);
   const params = {
     index,
-    filterPath: ['aggregations'],
+    filter_path: ['aggregations'],
     body: {
       size: 0,
       query: {
diff --git a/x-pack/plugins/monitoring/server/lib/alerts/fetch_missing_monitoring_data.ts b/x-pack/plugins/monitoring/server/lib/alerts/fetch_missing_monitoring_data.ts
index a7b4a3a0232072..856ca7c9198851 100644
--- a/x-pack/plugins/monitoring/server/lib/alerts/fetch_missing_monitoring_data.ts
+++ b/x-pack/plugins/monitoring/server/lib/alerts/fetch_missing_monitoring_data.ts
@@ -52,7 +52,7 @@ export async function fetchMissingMonitoringData(
   const endMs = nowInMs;
   const params = {
     index,
-    filterPath: ['aggregations.clusters.buckets'],
+    filter_path: ['aggregations.clusters.buckets'],
     body: {
       size: 0,
       query: {
diff --git a/x-pack/plugins/monitoring/server/lib/alerts/fetch_nodes_from_cluster_stats.ts b/x-pack/plugins/monitoring/server/lib/alerts/fetch_nodes_from_cluster_stats.ts
index 5f867ca5b6edf5..dcc8e6516c69bd 100644
--- a/x-pack/plugins/monitoring/server/lib/alerts/fetch_nodes_from_cluster_stats.ts
+++ b/x-pack/plugins/monitoring/server/lib/alerts/fetch_nodes_from_cluster_stats.ts
@@ -30,7 +30,7 @@ export async function fetchNodesFromClusterStats(
 ): Promise<AlertClusterStatsNodes[]> {
   const params = {
     index,
-    filterPath: ['aggregations.clusters.buckets'],
+    filter_path: ['aggregations.clusters.buckets'],
     body: {
       size: 0,
       sort: [
diff --git a/x-pack/plugins/monitoring/server/lib/alerts/fetch_thread_pool_rejections_stats.ts b/x-pack/plugins/monitoring/server/lib/alerts/fetch_thread_pool_rejections_stats.ts
index 954ec3877144fe..132f7692a7579a 100644
--- a/x-pack/plugins/monitoring/server/lib/alerts/fetch_thread_pool_rejections_stats.ts
+++ b/x-pack/plugins/monitoring/server/lib/alerts/fetch_thread_pool_rejections_stats.ts
@@ -41,7 +41,7 @@ export async function fetchThreadPoolRejectionStats(
   const clustersIds = clusters.map((cluster) => cluster.clusterUuid);
   const params = {
     index,
-    filterPath: ['aggregations'],
+    filter_path: ['aggregations'],
     body: {
       size: 0,
       query: {
diff --git a/x-pack/plugins/monitoring/server/lib/apm/_get_time_of_last_event.ts b/x-pack/plugins/monitoring/server/lib/apm/_get_time_of_last_event.ts
index 93ff966b5def54..398428f89a4baa 100644
--- a/x-pack/plugins/monitoring/server/lib/apm/_get_time_of_last_event.ts
+++ b/x-pack/plugins/monitoring/server/lib/apm/_get_time_of_last_event.ts
@@ -30,7 +30,7 @@ export async function getTimeOfLastEvent({
   const params = {
     index: apmIndexPattern,
     size: 1,
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       _source: ['beats_stats.timestamp', '@timestamp'],
       sort: [
diff --git a/x-pack/plugins/monitoring/server/lib/apm/get_apm_info.ts b/x-pack/plugins/monitoring/server/lib/apm/get_apm_info.ts
index 53a4aeb06bcc16..3721bf873a4177 100644
--- a/x-pack/plugins/monitoring/server/lib/apm/get_apm_info.ts
+++ b/x-pack/plugins/monitoring/server/lib/apm/get_apm_info.ts
@@ -97,8 +97,8 @@ export async function getApmInfo(
   const params = {
     index: apmIndexPattern,
     size: 1,
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       'hits.hits._source.beats_stats.beat.host',
       'hits.hits._source.beats_stats.beat.version',
       'hits.hits._source.beats_stats.beat.name',
diff --git a/x-pack/plugins/monitoring/server/lib/apm/get_apms.ts b/x-pack/plugins/monitoring/server/lib/apm/get_apms.ts
index b606eaf5fe7939..be3bb6fdfd6615 100644
--- a/x-pack/plugins/monitoring/server/lib/apm/get_apms.ts
+++ b/x-pack/plugins/monitoring/server/lib/apm/get_apms.ts
@@ -109,8 +109,8 @@ export async function getApms(req: LegacyRequest, apmIndexPattern: string, clust
   const params = {
     index: apmIndexPattern,
     size: config.get('monitoring.ui.max_bucket_size'), // FIXME
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       // only filter path can filter for inner_hits
       'hits.hits._source.timestamp',
       'hits.hits._source.@timestamp',
diff --git a/x-pack/plugins/monitoring/server/lib/apm/get_apms_for_clusters.js b/x-pack/plugins/monitoring/server/lib/apm/get_apms_for_clusters.js
index 45bbe35ebd59d1..0c96e0e2305850 100644
--- a/x-pack/plugins/monitoring/server/lib/apm/get_apms_for_clusters.js
+++ b/x-pack/plugins/monitoring/server/lib/apm/get_apms_for_clusters.js
@@ -46,8 +46,8 @@ export function getApmsForClusters(req, apmIndexPattern, clusters) {
       const params = {
         index: apmIndexPattern,
         size: 0,
-        ignoreUnavailable: true,
-        filterPath: apmAggFilterPath,
+        ignore_unavailable: true,
+        filter_path: apmAggFilterPath,
         body: {
           query: createApmQuery({
             start,
diff --git a/x-pack/plugins/monitoring/server/lib/apm/get_stats.js b/x-pack/plugins/monitoring/server/lib/apm/get_stats.js
index 7dd1b652254cb8..2abd81e325f5ec 100644
--- a/x-pack/plugins/monitoring/server/lib/apm/get_stats.js
+++ b/x-pack/plugins/monitoring/server/lib/apm/get_stats.js
@@ -34,9 +34,9 @@ export async function getStats(req, apmIndexPattern, clusterUuid) {
 
   const params = {
     index: apmIndexPattern,
-    filterPath: apmAggFilterPath,
+    filter_path: apmAggFilterPath,
     size: 0,
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       query: createApmQuery({
         start,
diff --git a/x-pack/plugins/monitoring/server/lib/beats/get_beat_summary.ts b/x-pack/plugins/monitoring/server/lib/beats/get_beat_summary.ts
index 13b4f0041c99b7..d67f32e64ba71d 100644
--- a/x-pack/plugins/monitoring/server/lib/beats/get_beat_summary.ts
+++ b/x-pack/plugins/monitoring/server/lib/beats/get_beat_summary.ts
@@ -89,8 +89,8 @@ export async function getBeatSummary(
   const params = {
     index: beatsIndexPattern,
     size: 1,
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       'hits.hits._source.beats_stats.beat.host',
       'hits.hits._source.beat.stats.beat.host',
       'hits.hits._source.beats_stats.beat.version',
diff --git a/x-pack/plugins/monitoring/server/lib/beats/get_beats.ts b/x-pack/plugins/monitoring/server/lib/beats/get_beats.ts
index 641039331bbcb6..fff2b55cf26163 100644
--- a/x-pack/plugins/monitoring/server/lib/beats/get_beats.ts
+++ b/x-pack/plugins/monitoring/server/lib/beats/get_beats.ts
@@ -121,8 +121,8 @@ export async function getBeats(req: LegacyRequest, beatsIndexPattern: string, cl
   const params = {
     index: beatsIndexPattern,
     size: config.get('monitoring.ui.max_bucket_size'), // FIXME
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       // only filter path can filter for inner_hits
       'hits.hits._source.beats_stats.beat.uuid',
       'hits.hits._source.beat.stats.beat.uuid',
diff --git a/x-pack/plugins/monitoring/server/lib/beats/get_beats_for_clusters.js b/x-pack/plugins/monitoring/server/lib/beats/get_beats_for_clusters.js
index 5ceca7a02d89b0..e7c4771dd601cc 100644
--- a/x-pack/plugins/monitoring/server/lib/beats/get_beats_for_clusters.js
+++ b/x-pack/plugins/monitoring/server/lib/beats/get_beats_for_clusters.js
@@ -44,8 +44,8 @@ export function getBeatsForClusters(req, beatsIndexPattern, clusters) {
       const params = {
         index: beatsIndexPattern,
         size: 0,
-        ignoreUnavailable: true,
-        filterPath: beatsAggFilterPath,
+        ignore_unavailable: true,
+        filter_path: beatsAggFilterPath,
         body: {
           query: createBeatsQuery({
             start,
diff --git a/x-pack/plugins/monitoring/server/lib/beats/get_latest_stats.js b/x-pack/plugins/monitoring/server/lib/beats/get_latest_stats.js
index f3f296fc09a389..fb40df115d19ac 100644
--- a/x-pack/plugins/monitoring/server/lib/beats/get_latest_stats.js
+++ b/x-pack/plugins/monitoring/server/lib/beats/get_latest_stats.js
@@ -81,8 +81,8 @@ export function getLatestStats(req, beatsIndexPattern, clusterUuid) {
   const params = {
     index: beatsIndexPattern,
     size: 0,
-    ignoreUnavailable: true,
-    filterPath: 'aggregations',
+    ignore_unavailable: true,
+    filter_path: 'aggregations',
     body: {
       query: createBeatsQuery({
         clusterUuid,
diff --git a/x-pack/plugins/monitoring/server/lib/beats/get_stats.js b/x-pack/plugins/monitoring/server/lib/beats/get_stats.js
index aa3d3947adccf5..3af51d909697ff 100644
--- a/x-pack/plugins/monitoring/server/lib/beats/get_stats.js
+++ b/x-pack/plugins/monitoring/server/lib/beats/get_stats.js
@@ -33,9 +33,9 @@ export async function getStats(req, beatsIndexPattern, clusterUuid) {
 
   const params = {
     index: beatsIndexPattern,
-    filterPath: beatsAggFilterPath,
+    filter_path: beatsAggFilterPath,
     size: 0,
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       query: createBeatsQuery({
         start,
diff --git a/x-pack/plugins/monitoring/server/lib/cluster/flag_supported_clusters.ts b/x-pack/plugins/monitoring/server/lib/cluster/flag_supported_clusters.ts
index 42041832cfee5d..820b1bf24c6a13 100644
--- a/x-pack/plugins/monitoring/server/lib/cluster/flag_supported_clusters.ts
+++ b/x-pack/plugins/monitoring/server/lib/cluster/flag_supported_clusters.ts
@@ -30,8 +30,8 @@ async function findSupportedBasicLicenseCluster(
   const kibanaDataResult: ElasticsearchResponse = (await callWithRequest(req, 'search', {
     index: kbnIndexPattern,
     size: 1,
-    ignoreUnavailable: true,
-    filterPath: ['hits.hits._source.cluster_uuid', 'hits.hits._source.cluster.id'],
+    ignore_unavailable: true,
+    filter_path: ['hits.hits._source.cluster_uuid', 'hits.hits._source.cluster.id'],
     body: {
       sort: { timestamp: { order: 'desc', unmapped_type: 'long' } },
       query: {
diff --git a/x-pack/plugins/monitoring/server/lib/cluster/get_cluster_license.ts b/x-pack/plugins/monitoring/server/lib/cluster/get_cluster_license.ts
index d1fa0efcbca2de..8ed5578e574a0c 100644
--- a/x-pack/plugins/monitoring/server/lib/cluster/get_cluster_license.ts
+++ b/x-pack/plugins/monitoring/server/lib/cluster/get_cluster_license.ts
@@ -20,8 +20,8 @@ export function getClusterLicense(req: LegacyRequest, esIndexPattern: string, cl
   const params = {
     index: esIndexPattern,
     size: 1,
-    ignoreUnavailable: true,
-    filterPath: 'hits.hits._source.license',
+    ignore_unavailable: true,
+    filter_path: ['hits.hits._source.license'],
     body: {
       sort: { timestamp: { order: 'desc', unmapped_type: 'long' } },
       query: createQuery({
diff --git a/x-pack/plugins/monitoring/server/lib/cluster/get_clusters_state.ts b/x-pack/plugins/monitoring/server/lib/cluster/get_clusters_state.ts
index 2cec89b18aecda..d732b43bc203b4 100644
--- a/x-pack/plugins/monitoring/server/lib/cluster/get_clusters_state.ts
+++ b/x-pack/plugins/monitoring/server/lib/cluster/get_clusters_state.ts
@@ -66,8 +66,8 @@ export function getClustersState(
   const params = {
     index: esIndexPattern,
     size: clusterUuids.length,
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       'hits.hits._source.cluster_uuid',
       'hits.hits._source.elasticsearch.cluster.id',
       'hits.hits._source.cluster_state',
diff --git a/x-pack/plugins/monitoring/server/lib/cluster/get_clusters_stats.ts b/x-pack/plugins/monitoring/server/lib/cluster/get_clusters_stats.ts
index 4067293e7829da..6eb21165d7256b 100644
--- a/x-pack/plugins/monitoring/server/lib/cluster/get_clusters_stats.ts
+++ b/x-pack/plugins/monitoring/server/lib/cluster/get_clusters_stats.ts
@@ -53,8 +53,8 @@ function fetchClusterStats(req: LegacyRequest, esIndexPattern: string, clusterUu
   const params = {
     index: esIndexPattern,
     size: config.get('monitoring.ui.max_bucket_size'),
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       'hits.hits._index',
       'hits.hits._source.cluster_uuid',
       'hits.hits._source.elasticsearch.cluster.id',
diff --git a/x-pack/plugins/monitoring/server/lib/details/get_series.js b/x-pack/plugins/monitoring/server/lib/details/get_series.js
index ca062ad5599fac..d06ff950449dc0 100644
--- a/x-pack/plugins/monitoring/server/lib/details/get_series.js
+++ b/x-pack/plugins/monitoring/server/lib/details/get_series.js
@@ -150,7 +150,7 @@ async function fetchSeries(
   const params = {
     index: indexPattern,
     size: 0,
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       query: createQuery({
         start: adjustedMin,
diff --git a/x-pack/plugins/monitoring/server/lib/elasticsearch/ccr.ts b/x-pack/plugins/monitoring/server/lib/elasticsearch/ccr.ts
index d0abed2ad8b8da..482cbd3601993c 100644
--- a/x-pack/plugins/monitoring/server/lib/elasticsearch/ccr.ts
+++ b/x-pack/plugins/monitoring/server/lib/elasticsearch/ccr.ts
@@ -27,7 +27,7 @@ export async function checkCcrEnabled(req: LegacyRequest, esIndexPattern: string
   const params = {
     index: esIndexPattern,
     size: 1,
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       query: createQuery({
         type: 'cluster_stats',
@@ -38,7 +38,7 @@ export async function checkCcrEnabled(req: LegacyRequest, esIndexPattern: string
       }),
       sort: [{ timestamp: { order: 'desc', unmapped_type: 'long' } }],
     },
-    filterPath: [
+    filter_path: [
       'hits.hits._source.stack_stats.xpack.ccr',
       'hits.hits._source.elasticsearch.cluster.stats.stack.xpack.ccr',
     ],
diff --git a/x-pack/plugins/monitoring/server/lib/elasticsearch/get_last_recovery.ts b/x-pack/plugins/monitoring/server/lib/elasticsearch/get_last_recovery.ts
index b6669342649332..43527f875cf729 100644
--- a/x-pack/plugins/monitoring/server/lib/elasticsearch/get_last_recovery.ts
+++ b/x-pack/plugins/monitoring/server/lib/elasticsearch/get_last_recovery.ts
@@ -97,7 +97,7 @@ export async function getLastRecovery(req: LegacyRequest, esIndexPattern: string
   const legacyParams = {
     index: esIndexPattern,
     size: 1,
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       _source: ['index_recovery.shards'],
       sort: { timestamp: { order: 'desc', unmapped_type: 'long' } },
diff --git a/x-pack/plugins/monitoring/server/lib/elasticsearch/get_ml_jobs.ts b/x-pack/plugins/monitoring/server/lib/elasticsearch/get_ml_jobs.ts
index 8b89416f14e9fa..df44036cd0cd82 100644
--- a/x-pack/plugins/monitoring/server/lib/elasticsearch/get_ml_jobs.ts
+++ b/x-pack/plugins/monitoring/server/lib/elasticsearch/get_ml_jobs.ts
@@ -47,8 +47,8 @@ export function getMlJobs(req: LegacyRequest, esIndexPattern: string) {
   const params = {
     index: esIndexPattern,
     size: maxBucketSize,
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       'hits.hits._source.job_stats.job_id',
       'hits.hits._source.elasticsearch.ml.job.id',
       'hits.hits._source.job_stats.state',
@@ -95,8 +95,8 @@ export function getMlJobsForCluster(
     const params = {
       index: esIndexPattern,
       size: 0,
-      ignoreUnavailable: true,
-      filterPath: 'aggregations.jobs_count.value',
+      ignore_unavailable: true,
+      filter_path: 'aggregations.jobs_count.value',
       body: {
         query: createQuery({ types: ['ml_job', 'job_stats'], start, end, clusterUuid, metric }),
         aggs: {
diff --git a/x-pack/plugins/monitoring/server/lib/elasticsearch/indices/get_index_summary.ts b/x-pack/plugins/monitoring/server/lib/elasticsearch/indices/get_index_summary.ts
index ee4988d773974f..8a03027a93a565 100644
--- a/x-pack/plugins/monitoring/server/lib/elasticsearch/indices/get_index_summary.ts
+++ b/x-pack/plugins/monitoring/server/lib/elasticsearch/indices/get_index_summary.ts
@@ -89,7 +89,7 @@ export function getIndexSummary(
   const params = {
     index: esIndexPattern,
     size: 1,
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       sort: { timestamp: { order: 'desc', unmapped_type: 'long' } },
       query: createQuery({
diff --git a/x-pack/plugins/monitoring/server/lib/elasticsearch/indices/get_indices.ts b/x-pack/plugins/monitoring/server/lib/elasticsearch/indices/get_indices.ts
index 9a61d6c603b973..0a9993769a6e5c 100644
--- a/x-pack/plugins/monitoring/server/lib/elasticsearch/indices/get_indices.ts
+++ b/x-pack/plugins/monitoring/server/lib/elasticsearch/indices/get_indices.ts
@@ -116,8 +116,8 @@ export function buildGetIndicesQuery(
   return {
     index: esIndexPattern,
     size,
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       // only filter path can filter for inner_hits
       'hits.hits._source.index_stats.index',
       'hits.hits._source.elasticsearch.index.name',
diff --git a/x-pack/plugins/monitoring/server/lib/elasticsearch/nodes/get_node_summary.ts b/x-pack/plugins/monitoring/server/lib/elasticsearch/nodes/get_node_summary.ts
index c7ca66753c73bf..79c44286717b45 100644
--- a/x-pack/plugins/monitoring/server/lib/elasticsearch/nodes/get_node_summary.ts
+++ b/x-pack/plugins/monitoring/server/lib/elasticsearch/nodes/get_node_summary.ts
@@ -124,7 +124,7 @@ export function getNodeSummary(
   const params = {
     index: esIndexPattern,
     size: 1,
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       sort: { timestamp: { order: 'desc', unmapped_type: 'long' } },
       query: createQuery({ type: 'node_stats', start, end, clusterUuid, metric, filters }),
diff --git a/x-pack/plugins/monitoring/server/lib/elasticsearch/nodes/get_nodes/get_node_ids.js b/x-pack/plugins/monitoring/server/lib/elasticsearch/nodes/get_nodes/get_node_ids.js
index 96b434b945ad46..87781417a07e5f 100644
--- a/x-pack/plugins/monitoring/server/lib/elasticsearch/nodes/get_nodes/get_node_ids.js
+++ b/x-pack/plugins/monitoring/server/lib/elasticsearch/nodes/get_nodes/get_node_ids.js
@@ -17,8 +17,8 @@ export async function getNodeIds(req, indexPattern, { clusterUuid }, size) {
   const params = {
     index: indexPattern,
     size: 0,
-    ignoreUnavailable: true,
-    filterPath: ['aggregations.composite_data.buckets'],
+    ignore_unavailable: true,
+    filter_path: ['aggregations.composite_data.buckets'],
     body: {
       query: createQuery({
         type: 'node_stats',
diff --git a/x-pack/plugins/monitoring/server/lib/elasticsearch/nodes/get_nodes/get_nodes.ts b/x-pack/plugins/monitoring/server/lib/elasticsearch/nodes/get_nodes/get_nodes.ts
index 2235d3d2f3224d..442a2b1b9b9c9b 100644
--- a/x-pack/plugins/monitoring/server/lib/elasticsearch/nodes/get_nodes/get_nodes.ts
+++ b/x-pack/plugins/monitoring/server/lib/elasticsearch/nodes/get_nodes/get_nodes.ts
@@ -76,7 +76,7 @@ export async function getNodes(
   const params = {
     index: esIndexPattern,
     size: config.get('monitoring.ui.max_bucket_size'),
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       query: createQuery({
         type: 'node_stats',
@@ -110,7 +110,7 @@ export async function getNodes(
       },
       sort: [{ timestamp: { order: 'desc', unmapped_type: 'long' } }],
     },
-    filterPath: [
+    filter_path: [
       'hits.hits._source.source_node',
       'hits.hits._source.service.address',
       'hits.hits._source.elasticsearch.node',
diff --git a/x-pack/plugins/monitoring/server/lib/elasticsearch/shards/get_indices_unassigned_shard_stats.ts b/x-pack/plugins/monitoring/server/lib/elasticsearch/shards/get_indices_unassigned_shard_stats.ts
index d3acf8ccaf4437..87f79ff5b9b44d 100644
--- a/x-pack/plugins/monitoring/server/lib/elasticsearch/shards/get_indices_unassigned_shard_stats.ts
+++ b/x-pack/plugins/monitoring/server/lib/elasticsearch/shards/get_indices_unassigned_shard_stats.ts
@@ -41,7 +41,7 @@ async function getUnassignedShardData(
   const params = {
     index: esIndexPattern,
     size: 0,
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       sort: { timestamp: { order: 'desc', unmapped_type: 'long' } },
       query: createQuery({
diff --git a/x-pack/plugins/monitoring/server/lib/elasticsearch/shards/get_nodes_shard_count.ts b/x-pack/plugins/monitoring/server/lib/elasticsearch/shards/get_nodes_shard_count.ts
index 7cda87bf09af83..12ce144ebf5c5a 100644
--- a/x-pack/plugins/monitoring/server/lib/elasticsearch/shards/get_nodes_shard_count.ts
+++ b/x-pack/plugins/monitoring/server/lib/elasticsearch/shards/get_nodes_shard_count.ts
@@ -39,7 +39,7 @@ async function getShardCountPerNode(
   const params = {
     index: esIndexPattern,
     size: 0,
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       sort: { timestamp: { order: 'desc', unmapped_type: 'long' } },
       query: createQuery({
diff --git a/x-pack/plugins/monitoring/server/lib/elasticsearch/shards/get_shard_allocation.ts b/x-pack/plugins/monitoring/server/lib/elasticsearch/shards/get_shard_allocation.ts
index b739b4a6533db2..d39e38eab21e93 100644
--- a/x-pack/plugins/monitoring/server/lib/elasticsearch/shards/get_shard_allocation.ts
+++ b/x-pack/plugins/monitoring/server/lib/elasticsearch/shards/get_shard_allocation.ts
@@ -103,7 +103,7 @@ export function getShardAllocation(
   const params = {
     index: esIndexPattern,
     size: config.get('monitoring.ui.max_bucket_size'),
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       query: createQuery({ types: ['shard', 'shards'], clusterUuid, metric, filters }),
     },
diff --git a/x-pack/plugins/monitoring/server/lib/elasticsearch/shards/get_shard_stats.ts b/x-pack/plugins/monitoring/server/lib/elasticsearch/shards/get_shard_stats.ts
index 5219a2e9286f5b..e0e6854dba05f2 100644
--- a/x-pack/plugins/monitoring/server/lib/elasticsearch/shards/get_shard_stats.ts
+++ b/x-pack/plugins/monitoring/server/lib/elasticsearch/shards/get_shard_stats.ts
@@ -96,7 +96,7 @@ export function getShardStats(
   const params = {
     index: esIndexPattern,
     size: 0,
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       sort: { timestamp: { order: 'desc', unmapped_type: 'long' } },
       query: createQuery({
diff --git a/x-pack/plugins/monitoring/server/lib/elasticsearch/verify_monitoring_auth.js b/x-pack/plugins/monitoring/server/lib/elasticsearch/verify_monitoring_auth.js
index 1895c36699e50f..e4cee4d4455cab 100644
--- a/x-pack/plugins/monitoring/server/lib/elasticsearch/verify_monitoring_auth.js
+++ b/x-pack/plugins/monitoring/server/lib/elasticsearch/verify_monitoring_auth.js
@@ -53,7 +53,7 @@ async function verifyHasPrivileges(req) {
           },
         ],
       },
-      ignoreUnavailable: true, // we allow 404 incase the user shutdown security in-between the check and now
+      ignore_unavailable: true, // we allow 404 incase the user shutdown security in-between the check and now
     });
   } catch (err) {
     if (
diff --git a/x-pack/plugins/monitoring/server/lib/elasticsearch_settings/cluster.js b/x-pack/plugins/monitoring/server/lib/elasticsearch_settings/cluster.js
index a1ece9e302b2a7..1c20634c102204 100644
--- a/x-pack/plugins/monitoring/server/lib/elasticsearch_settings/cluster.js
+++ b/x-pack/plugins/monitoring/server/lib/elasticsearch_settings/cluster.js
@@ -34,15 +34,6 @@ export async function checkClusterSettings(req) {
   const { callWithRequest } = req.server.plugins.elasticsearch.getCluster('admin');
   const { cloud } = req.server.newPlatform.setup.plugins;
   const isCloudEnabled = !!(cloud && cloud.isCloudEnabled);
-  const response = await callWithRequest(req, 'transport.request', {
-    method: 'GET',
-    path: '/_cluster/settings?include_defaults',
-    filter_path: [
-      'persistent.xpack.monitoring',
-      'transient.xpack.monitoring',
-      'defaults.xpack.monitoring',
-    ],
-  });
-
+  const response = await callWithRequest(req, 'cluster.getSettings', { include_defaults: true });
   return handleResponse(response, isCloudEnabled);
 }
diff --git a/x-pack/plugins/monitoring/server/lib/kibana/get_kibana_info.ts b/x-pack/plugins/monitoring/server/lib/kibana/get_kibana_info.ts
index 3b0af657947e54..15cc9904dd060c 100644
--- a/x-pack/plugins/monitoring/server/lib/kibana/get_kibana_info.ts
+++ b/x-pack/plugins/monitoring/server/lib/kibana/get_kibana_info.ts
@@ -36,8 +36,8 @@ export function getKibanaInfo(
   const params = {
     index: kbnIndexPattern,
     size: 1,
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       'hits.hits._source.kibana_stats.kibana',
       'hits.hits._source.kibana.kibana',
       'hits.hits._source.kibana_stats.os.memory.free_in_bytes',
diff --git a/x-pack/plugins/monitoring/server/lib/kibana/get_kibanas.ts b/x-pack/plugins/monitoring/server/lib/kibana/get_kibanas.ts
index 4da4c40b25568e..b89ff7a326d80f 100644
--- a/x-pack/plugins/monitoring/server/lib/kibana/get_kibanas.ts
+++ b/x-pack/plugins/monitoring/server/lib/kibana/get_kibanas.ts
@@ -71,7 +71,7 @@ export async function getKibanas(
   const params = {
     index: kbnIndexPattern,
     size: config.get('monitoring.ui.max_bucket_size'),
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       query: createQuery({
         types: ['kibana_stats', 'stats'],
diff --git a/x-pack/plugins/monitoring/server/lib/kibana/get_kibanas_for_clusters.js b/x-pack/plugins/monitoring/server/lib/kibana/get_kibanas_for_clusters.js
index 7d648601229224..141596ffd2f6fb 100644
--- a/x-pack/plugins/monitoring/server/lib/kibana/get_kibanas_for_clusters.js
+++ b/x-pack/plugins/monitoring/server/lib/kibana/get_kibanas_for_clusters.js
@@ -37,7 +37,7 @@ export function getKibanasForClusters(req, kbnIndexPattern, clusters) {
     const params = {
       index: kbnIndexPattern,
       size: 0,
-      ignoreUnavailable: true,
+      ignore_unavailable: true,
       body: {
         query: createQuery({
           types: ['stats', 'kibana_stats'],
diff --git a/x-pack/plugins/monitoring/server/lib/logs/get_log_types.ts b/x-pack/plugins/monitoring/server/lib/logs/get_log_types.ts
index 82b73c6b87f060..bbb48c43033da3 100644
--- a/x-pack/plugins/monitoring/server/lib/logs/get_log_types.ts
+++ b/x-pack/plugins/monitoring/server/lib/logs/get_log_types.ts
@@ -84,8 +84,8 @@ export async function getLogTypes(
   const params = {
     index: filebeatIndexPattern,
     size: 0,
-    filterPath: ['aggregations.levels.buckets', 'aggregations.types.buckets'],
-    ignoreUnavailable: true,
+    filter_path: ['aggregations.levels.buckets', 'aggregations.types.buckets'],
+    ignore_unavailable: true,
     body: {
       sort: { '@timestamp': { order: 'desc', unmapped_type: 'long' } },
       query: {
diff --git a/x-pack/plugins/monitoring/server/lib/logs/get_logs.ts b/x-pack/plugins/monitoring/server/lib/logs/get_logs.ts
index 11e8f6550bcb7d..4c21422a5d0cf7 100644
--- a/x-pack/plugins/monitoring/server/lib/logs/get_logs.ts
+++ b/x-pack/plugins/monitoring/server/lib/logs/get_logs.ts
@@ -100,7 +100,7 @@ export async function getLogs(
   const params = {
     index: filebeatIndexPattern,
     size: Math.min(50, config.get('monitoring.ui.elasticsearch.logFetchCount')),
-    filterPath: [
+    filter_path: [
       'hits.hits._source.message',
       'hits.hits._source.log.level',
       'hits.hits._source.@timestamp',
@@ -109,7 +109,7 @@ export async function getLogs(
       'hits.hits._source.elasticsearch.index.name',
       'hits.hits._source.elasticsearch.node.name',
     ],
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       sort: { '@timestamp': { order: 'desc', unmapped_type: 'long' } },
       query: {
diff --git a/x-pack/plugins/monitoring/server/lib/logstash/get_logstash_for_clusters.js b/x-pack/plugins/monitoring/server/lib/logstash/get_logstash_for_clusters.js
index 58155e35ad52f9..17f76834b333ad 100644
--- a/x-pack/plugins/monitoring/server/lib/logstash/get_logstash_for_clusters.js
+++ b/x-pack/plugins/monitoring/server/lib/logstash/get_logstash_for_clusters.js
@@ -48,7 +48,7 @@ export function getLogstashForClusters(req, lsIndexPattern, clusters) {
     const params = {
       index: lsIndexPattern,
       size: 0,
-      ignoreUnavailable: true,
+      ignore_unavailable: true,
       body: {
         query: createQuery({
           types: ['stats', 'logstash_stats'],
diff --git a/x-pack/plugins/monitoring/server/lib/logstash/get_node_info.ts b/x-pack/plugins/monitoring/server/lib/logstash/get_node_info.ts
index 954b78c432374f..d047729a0b3c22 100644
--- a/x-pack/plugins/monitoring/server/lib/logstash/get_node_info.ts
+++ b/x-pack/plugins/monitoring/server/lib/logstash/get_node_info.ts
@@ -45,8 +45,8 @@ export function getNodeInfo(
   const params = {
     index: lsIndexPattern,
     size: 1,
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       'hits.hits._source.logstash_stats.events',
       'hits.hits._source.logstash.node.stats.events',
       'hits.hits._source.logstash_stats.jvm.uptime_in_millis',
diff --git a/x-pack/plugins/monitoring/server/lib/logstash/get_nodes.ts b/x-pack/plugins/monitoring/server/lib/logstash/get_nodes.ts
index 9db59fec25530e..42d1b69aee5f37 100644
--- a/x-pack/plugins/monitoring/server/lib/logstash/get_nodes.ts
+++ b/x-pack/plugins/monitoring/server/lib/logstash/get_nodes.ts
@@ -82,7 +82,7 @@ export async function getNodes(
   const params = {
     index: lsIndexPattern,
     size: config.get('monitoring.ui.max_bucket_size'), // FIXME
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       query: createQuery({
         start,
diff --git a/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_ids.js b/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_ids.js
index 1521c5d3773d0e..2846a968bfed6d 100644
--- a/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_ids.js
+++ b/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_ids.js
@@ -27,8 +27,8 @@ export async function getLogstashPipelineIds(
   const params = {
     index: logstashIndexPattern,
     size: 0,
-    ignoreUnavailable: true,
-    filterPath: ['aggregations.nest.id.buckets', 'aggregations.nest_mb.id.buckets'],
+    ignore_unavailable: true,
+    filter_path: ['aggregations.nest.id.buckets', 'aggregations.nest_mb.id.buckets'],
     body: {
       query: createQuery({
         start,
diff --git a/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_state_document.ts b/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_state_document.ts
index e261505e2d1b01..61c99c3a069b32 100644
--- a/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_state_document.ts
+++ b/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_state_document.ts
@@ -42,7 +42,7 @@ export async function getPipelineStateDocument(
   const params = {
     index: logstashIndexPattern,
     size: 1,
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       _source: { excludes: 'logstash_state.pipeline.representation.plugins' },
       sort: { timestamp: { order: 'desc', unmapped_type: 'long' } },
diff --git a/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_stats_aggregation.js b/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_stats_aggregation.js
index 2e35a4639fa5a6..4d9d2a720a1627 100644
--- a/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_stats_aggregation.js
+++ b/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_stats_aggregation.js
@@ -106,8 +106,8 @@ function fetchPipelineLatestStats(
   const params = {
     index: logstashIndexPattern,
     size: 0,
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       'aggregations.pipelines.scoped.vertices.vertex_id.buckets.key',
       'aggregations.pipelines.scoped.vertices.vertex_id.buckets.events_in_total',
       'aggregations.pipelines.scoped.vertices.vertex_id.buckets.events_out_total',
diff --git a/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_versions.js b/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_versions.js
index d1121c78407ffc..c52d41a363055f 100644
--- a/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_versions.js
+++ b/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_versions.js
@@ -82,7 +82,7 @@ function fetchPipelineVersions(...args) {
   const params = {
     index: logstashIndexPattern,
     size: 0,
-    ignoreUnavailable: true,
+    ignore_unavailable: true,
     body: {
       sort: { timestamp: { order: 'desc', unmapped_type: 'long' } },
       query,
diff --git a/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_vertex_stats_aggregation.js b/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_vertex_stats_aggregation.js
index 81d1f2bf572176..97a8c463a2259f 100644
--- a/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_vertex_stats_aggregation.js
+++ b/x-pack/plugins/monitoring/server/lib/logstash/get_pipeline_vertex_stats_aggregation.js
@@ -155,8 +155,8 @@ function fetchPipelineVertexTimeSeriesStats(
   const params = {
     index: logstashIndexPattern,
     size: 0,
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       'aggregations.timeseries.buckets.key',
       'aggregations.timeseries.buckets.pipelines.scoped.vertices.vertex_id.events_in_total',
       'aggregations.timeseries.buckets.pipelines.scoped.vertices.vertex_id.events_out_total',
diff --git a/x-pack/plugins/monitoring/server/lib/setup/collection/get_collection_status.js b/x-pack/plugins/monitoring/server/lib/setup/collection/get_collection_status.js
index 36a48002005b3d..b9ce355b44b625 100644
--- a/x-pack/plugins/monitoring/server/lib/setup/collection/get_collection_status.js
+++ b/x-pack/plugins/monitoring/server/lib/setup/collection/get_collection_status.js
@@ -57,8 +57,8 @@ const getRecentMonitoringDocuments = async (req, indexPatterns, clusterUuid, nod
   const params = {
     index: Object.values(indexPatterns),
     size: 0,
-    ignoreUnavailable: true,
-    filterPath: ['aggregations.indices.buckets'],
+    ignore_unavailable: true,
+    filter_path: ['aggregations.indices.buckets'],
     body: {
       query: {
         bool: {
@@ -206,8 +206,8 @@ async function doesIndexExist(req, index) {
     index,
     size: 0,
     terminate_after: 1,
-    ignoreUnavailable: true,
-    filterPath: ['hits.total.value'],
+    ignore_unavailable: true,
+    filter_path: ['hits.total.value'],
   };
   const { callWithRequest } = req.server.plugins.elasticsearch.getCluster('monitoring');
   const response = await callWithRequest(req, 'search', params);
diff --git a/x-pack/plugins/monitoring/server/license_service.ts b/x-pack/plugins/monitoring/server/license_service.ts
index fde22aaefa5dd2..ab10193fc93cbd 100644
--- a/x-pack/plugins/monitoring/server/license_service.ts
+++ b/x-pack/plugins/monitoring/server/license_service.ts
@@ -6,16 +6,17 @@
  */
 
 import { Subscription } from 'rxjs';
-import { ILegacyCustomClusterClient } from 'kibana/server';
+import { IClusterClient, ILegacyClusterClient } from 'kibana/server';
 import { ILicense, LicenseFeature } from '../../licensing/common/types';
 import { LicensingPluginStart } from '../../licensing/server';
 import { MonitoringConfig } from './config';
 import { Logger } from '../../../../src/core/server';
 import { MonitoringLicenseService } from './types';
+import { EndpointTypes, Globals, ClientParams } from './static_globals';
 
 interface SetupDeps {
   licensing: LicensingPluginStart;
-  monitoringClient: ILegacyCustomClusterClient;
+  monitoringClient: IClusterClient;
   config: MonitoringConfig;
   log: Logger;
 }
@@ -27,8 +28,15 @@ const defaultLicenseFeature: LicenseFeature = {
 
 export class LicenseService {
   public setup({ licensing, monitoringClient, config, log }: SetupDeps): MonitoringLicenseService {
+    // TODO: This needs to be changed to an IClusterClient as when the Licensing server
+    // is upgraded to the new client.
+    const fakeLegacyClusterClient = {
+      callAsInternalUser: (endpoint: EndpointTypes, options: ClientParams) =>
+        Globals.app.getLegacyClusterShim(monitoringClient.asInternalUser, endpoint, options),
+    } as ILegacyClusterClient;
+
     const { refresh, license$ } = licensing.createLicensePoller(
-      monitoringClient,
+      fakeLegacyClusterClient,
       config.licensing.api_polling_frequency.asMilliseconds()
     );
 
diff --git a/x-pack/plugins/monitoring/server/plugin.ts b/x-pack/plugins/monitoring/server/plugin.ts
index 10724594ce576d..ca8d87bd300a08 100644
--- a/x-pack/plugins/monitoring/server/plugin.ts
+++ b/x-pack/plugins/monitoring/server/plugin.ts
@@ -15,11 +15,12 @@ import {
   KibanaRequest,
   KibanaResponseFactory,
   CoreSetup,
-  ILegacyCustomClusterClient,
+  ICustomClusterClient,
   CoreStart,
   CustomHttpResponseOptions,
   ResponseError,
   Plugin,
+  SharedGlobalConfig,
 } from 'kibana/server';
 import { DEFAULT_APP_CATEGORIES } from '../../../../src/core/server';
 import {
@@ -33,8 +34,6 @@ import { MonitoringConfig, createConfig, configSchema } from './config';
 import { requireUIRoutes } from './routes';
 import { initBulkUploader } from './kibana_monitoring';
 import { initInfraSource } from './lib/logs/init_infra_source';
-import { mbSafeQuery } from './lib/mb_safe_query';
-import { instantiateClient } from './es_client/instantiate_client';
 import { registerCollectors } from './kibana_monitoring/collectors';
 import { registerMonitoringTelemetryCollection } from './telemetry_collection';
 import { LicenseService } from './license_service';
@@ -51,7 +50,8 @@ import {
   RequestHandlerContextMonitoringPlugin,
 } from './types';
 
-import { Globals } from './static_globals';
+import { Globals, EndpointTypes } from './static_globals';
+import { instantiateClient } from './es_client/instantiate_client';
 
 // This is used to test the version of kibana
 const snapshotRegex = /-snapshot/i;
@@ -71,50 +71,68 @@ export class MonitoringPlugin
   private readonly initializerContext: PluginInitializerContext;
   private readonly log: Logger;
   private readonly getLogger: (...scopes: string[]) => Logger;
-  private cluster = {} as ILegacyCustomClusterClient;
+  private cluster = {} as ICustomClusterClient;
   private licenseService = {} as MonitoringLicenseService;
   private monitoringCore = {} as MonitoringCore;
   private legacyShimDependencies = {} as LegacyShimDependencies;
-  private bulkUploader: IBulkUploader | undefined;
+  private bulkUploader?: IBulkUploader;
+
+  private readonly config: MonitoringConfig;
+  private readonly legacyConfig: SharedGlobalConfig;
+  private coreSetup?: CoreSetup;
+  private setupPlugins?: PluginsSetup;
 
   constructor(initializerContext: PluginInitializerContext) {
     this.initializerContext = initializerContext;
     this.log = initializerContext.logger.get(LOGGING_TAG);
     this.getLogger = (...scopes: string[]) => initializerContext.logger.get(LOGGING_TAG, ...scopes);
+    this.config = createConfig(this.initializerContext.config.get<TypeOf<typeof configSchema>>());
+    this.legacyConfig = this.initializerContext.config.legacy.get();
   }
 
-  setup(core: CoreSetup, plugins: PluginsSetup) {
-    const config = createConfig(this.initializerContext.config.get<TypeOf<typeof configSchema>>());
-    const legacyConfig = this.initializerContext.config.legacy.get();
+  setup(coreSetup: CoreSetup, plugins: PluginsSetup) {
+    this.coreSetup = coreSetup;
+    this.setupPlugins = plugins;
 
-    const router = core.http.createRouter<RequestHandlerContextMonitoringPlugin>();
-    this.legacyShimDependencies = {
-      router,
-      instanceUuid: this.initializerContext.env.instanceUuid,
-      esDataClient: core.elasticsearch.legacy.client,
-      kibanaStatsCollector: plugins.usageCollection?.getCollectorByType(
-        KIBANA_STATS_TYPE_MONITORING
-      ),
-    };
+    const serverInfo = coreSetup.http.getServerInfo();
+    const kibanaMonitoringLog = this.getLogger(KIBANA_MONITORING_LOGGING_TAG);
+    this.bulkUploader = initBulkUploader({
+      config: this.config,
+      log: kibanaMonitoringLog,
+      opsMetrics$: coreSetup.metrics.getOpsMetrics$(),
+      statusGetter$: coreSetup.status.overall$,
+      kibanaStats: {
+        uuid: this.initializerContext.env.instanceUuid,
+        name: serverInfo.name,
+        index: this.legacyConfig.kibana.index,
+        host: serverInfo.hostname,
+        locale: i18n.getLocale(),
+        port: serverInfo.port.toString(),
+        transport_address: `${serverInfo.hostname}:${serverInfo.port}`,
+        version: this.initializerContext.env.packageInfo.version,
+        snapshot: snapshotRegex.test(this.initializerContext.env.packageInfo.version),
+      },
+    });
 
-    // Monitoring creates and maintains a connection to a potentially
-    // separate ES cluster - create this first
-    const cluster = (this.cluster = instantiateClient(
-      config.ui.elasticsearch,
-      this.log,
-      core.elasticsearch.legacy.createClient
-    ));
+    Globals.init({
+      initializerContext: this.initializerContext,
+      config: this.config!,
+      getLogger: this.getLogger,
+      log: this.log,
+      legacyConfig: this.legacyConfig,
+      coreSetup: this.coreSetup!,
+      setupPlugins: this.setupPlugins!,
+    });
 
-    Globals.init(core, plugins.cloud, cluster, config, this.getLogger);
-    const serverInfo = core.http.getServerInfo();
     const alerts = AlertsFactory.getAll();
     for (const alert of alerts) {
       plugins.alerting?.registerType(alert.getAlertType());
     }
+    const config = createConfig(this.initializerContext.config.get<TypeOf<typeof configSchema>>());
 
     // Register collector objects for stats to show up in the APIs
     if (plugins.usageCollection) {
-      core.savedObjects.registerType({
+      coreSetup.savedObjects.registerType({
         name: SAVED_OBJECT_TELEMETRY,
         hidden: true,
         namespaceType: 'agnostic',
@@ -127,33 +145,40 @@ export class MonitoringPlugin
         },
       });
 
-      registerCollectors(plugins.usageCollection, config, cluster);
+      registerCollectors(plugins.usageCollection, config, () => this.cluster);
       registerMonitoringTelemetryCollection(
         plugins.usageCollection,
-        cluster,
+        () => this.cluster,
         config.ui.max_bucket_size
       );
     }
+    if (config.ui.enabled) {
+      this.registerPluginInUI(plugins);
+    }
 
-    // Always create the bulk uploader
-    const kibanaMonitoringLog = this.getLogger(KIBANA_MONITORING_LOGGING_TAG);
-    const bulkUploader = (this.bulkUploader = initBulkUploader({
-      config,
-      log: kibanaMonitoringLog,
-      opsMetrics$: core.metrics.getOpsMetrics$(),
-      statusGetter$: core.status.overall$,
-      kibanaStats: {
-        uuid: this.initializerContext.env.instanceUuid,
-        name: serverInfo.name,
-        index: get(legacyConfig, 'kibana.index'),
-        host: serverInfo.hostname,
-        locale: i18n.getLocale(),
-        port: serverInfo.port.toString(),
-        transport_address: `${serverInfo.hostname}:${serverInfo.port}`,
-        version: this.initializerContext.env.packageInfo.version,
-        snapshot: snapshotRegex.test(this.initializerContext.env.packageInfo.version),
-      },
-    }));
+    return {
+      // OSS stats api needs to call this in order to centralize how
+      // we fetch kibana specific stats
+      getKibanaStats: () => this.bulkUploader?.getKibanaStats() || {},
+    };
+  }
+
+  init(cluster: ICustomClusterClient, coreStart: CoreStart) {
+    const config = createConfig(this.initializerContext.config.get<TypeOf<typeof configSchema>>());
+    const legacyConfig = this.initializerContext.config.legacy.get();
+    const coreSetup = this.coreSetup!;
+    const plugins = this.setupPlugins!;
+
+    const router = coreSetup.http.createRouter<RequestHandlerContextMonitoringPlugin>();
+    // const [{ elasticsearch }] = await core.getStartServices();
+    this.legacyShimDependencies = {
+      router,
+      instanceUuid: this.initializerContext.env.instanceUuid,
+      esDataClient: coreStart.elasticsearch.client.asInternalUser,
+      kibanaStatsCollector: plugins.usageCollection?.getCollectorByType(
+        KIBANA_STATS_TYPE_MONITORING
+      ),
+    };
 
     // If the UI is enabled, then we want to register it so it shows up
     // and start any other UI-related setup tasks
@@ -162,12 +187,11 @@ export class MonitoringPlugin
       this.monitoringCore = this.getLegacyShim(
         config,
         legacyConfig,
-        core.getStartServices as () => Promise<[CoreStart, PluginsStart, {}]>,
-        this.cluster,
+        coreSetup.getStartServices as () => Promise<[CoreStart, PluginsStart, {}]>,
+        cluster,
         plugins
       );
 
-      this.registerPluginInUI(plugins);
       requireUIRoutes(this.monitoringCore, {
         cluster,
         router,
@@ -177,16 +201,18 @@ export class MonitoringPlugin
       });
       initInfraSource(config, plugins.infra);
     }
-
-    return {
-      // OSS stats api needs to call this in order to centralize how
-      // we fetch kibana specific stats
-      getKibanaStats: () => bulkUploader.getKibanaStats(),
-    };
   }
 
-  async start(core: CoreStart, { licensing }: PluginsStart) {
-    const config = createConfig(this.initializerContext.config.get<TypeOf<typeof configSchema>>());
+  async start(coreStart: CoreStart, { licensing }: PluginsStart) {
+    const config = this.config!;
+    this.cluster = instantiateClient(
+      config.ui.elasticsearch,
+      this.log,
+      coreStart.elasticsearch.createClient
+    );
+
+    this.init(this.cluster, coreStart);
+
     // Start our license service which will ensure
     // the appropriate licenses are present
     this.licenseService = new LicenseService().setup({
@@ -209,7 +235,7 @@ export class MonitoringPlugin
           const monitoringBulkEnabled =
             mainMonitoring && mainMonitoring.isAvailable && mainMonitoring.isEnabled;
           if (monitoringBulkEnabled) {
-            this.bulkUploader?.start(core.elasticsearch.client.asInternalUser);
+            this.bulkUploader?.start(coreStart.elasticsearch.client.asInternalUser);
           } else {
             this.bulkUploader?.handleNotEnabled();
           }
@@ -227,7 +253,7 @@ export class MonitoringPlugin
   }
 
   stop() {
-    if (this.cluster) {
+    if (this.cluster && this.cluster.close) {
       this.cluster.close();
     }
     if (this.licenseService && this.licenseService.stop) {
@@ -281,7 +307,7 @@ export class MonitoringPlugin
     config: MonitoringConfig,
     legacyConfig: any,
     getCoreServices: () => Promise<[CoreStart, PluginsStart, {}]>,
-    cluster: ILegacyCustomClusterClient,
+    cluster: ICustomClusterClient,
     setupPlugins: PluginsSetup
   ): MonitoringCore {
     const router = this.legacyShimDependencies.router;
@@ -354,12 +380,12 @@ export class MonitoringPlugin
                 },
                 elasticsearch: {
                   getCluster: (name: string) => ({
-                    callWithRequest: async (_req: any, endpoint: string, params: any) => {
+                    callWithRequest: async (_req: any, endpoint: EndpointTypes, params: any) => {
                       const client =
-                        name === 'monitoring' ? cluster : this.legacyShimDependencies.esDataClient;
-                      return mbSafeQuery(() =>
-                        client.asScoped(req).callAsCurrentUser(endpoint, params)
-                      );
+                        name === 'monitoring'
+                          ? cluster.asScoped(req).asCurrentUser
+                          : context.core.elasticsearch.client.asCurrentUser;
+                      return await Globals.app.getLegacyClusterShim(client, endpoint, params);
                     },
                   }),
                 },
diff --git a/x-pack/plugins/monitoring/server/routes/api/v1/alerts/enable.ts b/x-pack/plugins/monitoring/server/routes/api/v1/alerts/enable.ts
index e48f424a3d8ee4..e21304e8458e37 100644
--- a/x-pack/plugins/monitoring/server/routes/api/v1/alerts/enable.ts
+++ b/x-pack/plugins/monitoring/server/routes/api/v1/alerts/enable.ts
@@ -93,7 +93,7 @@ export function enableAlertsRoute(server: LegacyServer, npRoute: RouteDependenci
 
         let createdAlerts: Array<SanitizedAlert<AlertTypeParams>> = [];
         const disabledWatcherClusterAlerts = await disableWatcherClusterAlerts(
-          npRoute.cluster.asScoped(request).callAsCurrentUser,
+          npRoute.cluster.asScoped(request).asCurrentUser,
           npRoute.logger
         );
 
diff --git a/x-pack/plugins/monitoring/server/routes/api/v1/elasticsearch/ccr.ts b/x-pack/plugins/monitoring/server/routes/api/v1/elasticsearch/ccr.ts
index 5cc7046777e265..73b646126ce988 100644
--- a/x-pack/plugins/monitoring/server/routes/api/v1/elasticsearch/ccr.ts
+++ b/x-pack/plugins/monitoring/server/routes/api/v1/elasticsearch/ccr.ts
@@ -99,7 +99,7 @@ function buildRequest(
   return {
     index: esIndexPattern,
     size: maxBucketSize,
-    filterPath: [
+    filter_path: [
       'hits.hits.inner_hits.by_shard.hits.hits._source.ccr_stats.read_exceptions',
       'hits.hits.inner_hits.by_shard.hits.hits._source.elasticsearch.ccr.read_exceptions',
       'hits.hits.inner_hits.by_shard.hits.hits._source.ccr_stats.follower_index',
diff --git a/x-pack/plugins/monitoring/server/routes/api/v1/elasticsearch/ccr_shard.ts b/x-pack/plugins/monitoring/server/routes/api/v1/elasticsearch/ccr_shard.ts
index ac5563430fb7ca..5ecb84d97618b0 100644
--- a/x-pack/plugins/monitoring/server/routes/api/v1/elasticsearch/ccr_shard.ts
+++ b/x-pack/plugins/monitoring/server/routes/api/v1/elasticsearch/ccr_shard.ts
@@ -35,7 +35,7 @@ async function getCcrStat(req: LegacyRequest, esIndexPattern: string, filters: u
   const params = {
     index: esIndexPattern,
     size: 1,
-    filterPath: [
+    filter_path: [
       'hits.hits._source.ccr_stats',
       'hits.hits._source.elasticsearch.ccr',
       'hits.hits._source.timestamp',
diff --git a/x-pack/plugins/monitoring/server/routes/api/v1/elasticsearch_settings/check/cluster.js b/x-pack/plugins/monitoring/server/routes/api/v1/elasticsearch_settings/check/cluster.js
index b8cdec9ed9b00f..6996c4885d25dc 100644
--- a/x-pack/plugins/monitoring/server/routes/api/v1/elasticsearch_settings/check/cluster.js
+++ b/x-pack/plugins/monitoring/server/routes/api/v1/elasticsearch_settings/check/cluster.js
@@ -23,6 +23,7 @@ export function clusterSettingsCheckRoute(server) {
         const response = await checkClusterSettings(req); // needs to be try/catch to handle privilege error
         return response;
       } catch (err) {
+        console.log(err);
         throw handleSettingsError(err);
       }
     },
diff --git a/x-pack/plugins/monitoring/server/routes/api/v1/elasticsearch_settings/check/internal_monitoring.ts b/x-pack/plugins/monitoring/server/routes/api/v1/elasticsearch_settings/check/internal_monitoring.ts
index 1c4ccdada095f6..c2bad7b905c5b1 100644
--- a/x-pack/plugins/monitoring/server/routes/api/v1/elasticsearch_settings/check/internal_monitoring.ts
+++ b/x-pack/plugins/monitoring/server/routes/api/v1/elasticsearch_settings/check/internal_monitoring.ts
@@ -7,6 +7,7 @@
 
 import { schema } from '@kbn/config-schema';
 import { RequestHandlerContext } from 'kibana/server';
+import { estypes } from '@elastic/elasticsearch';
 import {
   INDEX_PATTERN_ELASTICSEARCH,
   INDEX_PATTERN_KIBANA,
@@ -44,11 +45,11 @@ const queryBody = {
 };
 
 const checkLatestMonitoringIsLegacy = async (context: RequestHandlerContext, index: string) => {
-  const { client: esClient } = context.core.elasticsearch.legacy;
-  const result = await esClient.callAsCurrentUser('search', {
+  const client = context.core.elasticsearch.client.asCurrentUser;
+  const { body: result } = await client.search<estypes.SearchResponse<unknown>>({
     index,
     body: queryBody,
-  });
+  } as estypes.SearchRequest);
 
   const { aggregations } = result;
   const counts = {
@@ -62,7 +63,7 @@ const checkLatestMonitoringIsLegacy = async (context: RequestHandlerContext, ind
 
   const {
     types: { buckets },
-  } = aggregations;
+  } = aggregations as { types: { buckets: Array<{ key: string }> } };
   counts.mbIndicesCount = buckets.filter(({ key }: { key: string }) => key.includes('-mb-')).length;
 
   counts.legacyIndicesCount = buckets.length - counts.mbIndicesCount;
diff --git a/x-pack/plugins/monitoring/server/static_globals.ts b/x-pack/plugins/monitoring/server/static_globals.ts
index 1bb08d6cafc384..fc4ece32314864 100644
--- a/x-pack/plugins/monitoring/server/static_globals.ts
+++ b/x-pack/plugins/monitoring/server/static_globals.ts
@@ -5,20 +5,50 @@
  * 2.0.
  */
 
-import { CoreSetup, ILegacyCustomClusterClient, Logger } from 'kibana/server';
+import {
+  CoreSetup,
+  ElasticsearchClient,
+  Logger,
+  SharedGlobalConfig,
+  PluginInitializerContext,
+} from 'kibana/server';
 import url from 'url';
-import { CloudSetup } from '../../cloud/server';
+import { estypes } from '@elastic/elasticsearch';
 import { MonitoringConfig } from './config';
-
+import { PluginsSetup } from './types';
+import { mbSafeQuery } from './lib/mb_safe_query';
 type GetLogger = (...scopes: string[]) => Logger;
 
+interface InitSetupOptions {
+  initializerContext: PluginInitializerContext;
+  coreSetup: CoreSetup;
+  config: MonitoringConfig;
+  getLogger: GetLogger;
+  log: Logger;
+  legacyConfig: SharedGlobalConfig;
+  setupPlugins: PluginsSetup;
+}
+
+export type EndpointTypes =
+  | 'search'
+  | 'msearch'
+  | 'transport.request'
+  | 'cluster.putSettings'
+  | 'cluster.getSettings'
+  | string;
+export type ClientParams = estypes.SearchRequest | undefined;
+
 interface IAppGlobals {
   url: string;
   isCloud: boolean;
-  monitoringCluster: ILegacyCustomClusterClient;
   config: MonitoringConfig;
   getLogger: GetLogger;
   getKeyStoreValue: (key: string, storeValueMethod?: () => unknown) => unknown;
+  getLegacyClusterShim: (
+    client: ElasticsearchClient,
+    endpoint: EndpointTypes,
+    params: ClientParams
+  ) => any;
 }
 
 interface KeyStoreData {
@@ -37,22 +67,35 @@ const getKeyStoreValue = (key: string, storeValueMethod?: () => unknown) => {
 export class Globals {
   private static _app: IAppGlobals;
 
-  public static init(
-    coreSetup: CoreSetup,
-    cloud: CloudSetup | undefined,
-    monitoringCluster: ILegacyCustomClusterClient,
-    config: MonitoringConfig,
-    getLogger: GetLogger
-  ) {
+  public static init(options: InitSetupOptions) {
+    const { coreSetup, setupPlugins, config, getLogger } = options;
+    const getLegacyClusterShim = async (
+      client: ElasticsearchClient,
+      endpoint: EndpointTypes,
+      params: ClientParams
+    ): Promise<estypes.SearchResponse> =>
+      await mbSafeQuery(async () => {
+        const endpointMap: { [key: string]: (params: any) => any } = {
+          search: (p) => client.search(p),
+          msearch: (p) => client.msearch(p),
+          'transport.request': (p) => client.transport.request(p),
+          'cluster.getSettings': (p) => client.cluster.getSettings(p),
+          'cluster.putSettings': (p) => client.cluster.putSettings(p),
+        };
+        const { body } = await endpointMap[endpoint](params);
+        return body;
+      });
+
     const { protocol, hostname, port } = coreSetup.http.getServerInfo();
     const pathname = coreSetup.http.basePath.serverBasePath;
+
     Globals._app = {
       url: url.format({ protocol, hostname, port, pathname }),
-      isCloud: cloud?.isCloudEnabled || false,
-      monitoringCluster,
+      isCloud: setupPlugins.cloud?.isCloudEnabled || false,
       config,
       getLogger,
       getKeyStoreValue,
+      getLegacyClusterShim,
     };
   }
 
@@ -64,4 +107,6 @@ export class Globals {
     }
     return Globals._app;
   }
+
+  public static stop() {}
 }
diff --git a/x-pack/plugins/monitoring/server/telemetry_collection/get_all_stats.test.ts b/x-pack/plugins/monitoring/server/telemetry_collection/get_all_stats.test.ts
index 33487ecafd8c52..8933833bb068a2 100644
--- a/x-pack/plugins/monitoring/server/telemetry_collection/get_all_stats.test.ts
+++ b/x-pack/plugins/monitoring/server/telemetry_collection/get_all_stats.test.ts
@@ -5,6 +5,7 @@
  * 2.0.
  */
 
+import { ElasticsearchClient } from 'kibana/server';
 import sinon from 'sinon';
 import { getStackStats, getAllStats, handleAllStats } from './get_all_stats';
 import { ESClusterStats } from './get_es_stats';
@@ -13,7 +14,11 @@ import { LogstashStatsByClusterUuid } from './get_logstash_stats';
 
 describe('get_all_stats', () => {
   const timestamp = Date.now();
-  const callCluster = sinon.stub();
+  const searchMock = sinon.stub();
+  const callCluster = ({ search: searchMock } as unknown) as ElasticsearchClient;
+  afterEach(() => {
+    searchMock.reset();
+  });
 
   const esClusters = [
     { cluster_uuid: 'a' },
@@ -157,18 +162,20 @@ describe('get_all_stats', () => {
         },
       ];
 
-      callCluster
-        .withArgs('search')
+      searchMock
         .onCall(0)
-        .returns(Promise.resolve(esStatsResponse))
+        .returns(Promise.resolve({ body: esStatsResponse }))
         .onCall(1)
-        .returns(Promise.resolve(kibanaStatsResponse))
+        .returns(Promise.resolve({ body: kibanaStatsResponse }))
         .onCall(2)
-        .returns(Promise.resolve(logstashStatsResponse))
+        .returns(Promise.resolve({ body: logstashStatsResponse }))
+        .returns(Promise.resolve({ body: logstashStatsResponse }))
         .onCall(3)
-        .returns(Promise.resolve({})) // Beats stats
+        .returns(Promise.resolve({ body: {} })) // Beats stats
         .onCall(4)
-        .returns(Promise.resolve({})); // Beats state
+        .returns(Promise.resolve({ body: {} })) // Beats state
+        .onCall(5)
+        .returns(Promise.resolve({ body: {} })); // Logstash state
 
       expect(await getAllStats(['a'], callCluster, timestamp, 1)).toStrictEqual(allClusters);
     });
@@ -178,7 +185,7 @@ describe('get_all_stats', () => {
         aggregations: { cluster_uuids: { buckets: [] } },
       };
 
-      callCluster.withArgs('search').returns(Promise.resolve(clusterUuidsResponse));
+      searchMock.returns(Promise.resolve({ body: clusterUuidsResponse }));
 
       expect(await getAllStats([], callCluster, timestamp, 1)).toStrictEqual([]);
     });
diff --git a/x-pack/plugins/monitoring/server/telemetry_collection/get_all_stats.ts b/x-pack/plugins/monitoring/server/telemetry_collection/get_all_stats.ts
index 60b107cb293426..a0bad277dacf66 100644
--- a/x-pack/plugins/monitoring/server/telemetry_collection/get_all_stats.ts
+++ b/x-pack/plugins/monitoring/server/telemetry_collection/get_all_stats.ts
@@ -9,7 +9,7 @@ import { set } from '@elastic/safer-lodash-set';
 import { get, merge } from 'lodash';
 
 import moment from 'moment';
-import { LegacyAPICaller } from 'kibana/server';
+import { ElasticsearchClient } from 'kibana/server';
 import {
   LOGSTASH_SYSTEM_ID,
   KIBANA_SYSTEM_ID,
@@ -28,7 +28,7 @@ import { getLogstashStats, LogstashStatsByClusterUuid } from './get_logstash_sta
  */
 export async function getAllStats(
   clusterUuids: string[],
-  callCluster: LegacyAPICaller, // TODO: To be changed to the new ES client when the plugin migrates
+  callCluster: ElasticsearchClient,
   timestamp: number,
   maxBucketSize: number
 ) {
diff --git a/x-pack/plugins/monitoring/server/telemetry_collection/get_beats_stats.test.ts b/x-pack/plugins/monitoring/server/telemetry_collection/get_beats_stats.test.ts
index 3637ace3aeb63e..36477cb48cd891 100644
--- a/x-pack/plugins/monitoring/server/telemetry_collection/get_beats_stats.test.ts
+++ b/x-pack/plugins/monitoring/server/telemetry_collection/get_beats_stats.test.ts
@@ -7,6 +7,7 @@
 
 import { fetchBeatsStats, processResults } from './get_beats_stats';
 import sinon from 'sinon';
+import { ElasticsearchClient } from 'kibana/server';
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const beatsStatsResultSet = require('./__mocks__/fixtures/beats_stats_results');
 
@@ -23,40 +24,41 @@ describe('Get Beats Stats', () => {
     const clusterUuids = ['aCluster', 'bCluster', 'cCluster'];
     const start = new Date().toISOString();
     const end = new Date().toISOString();
-    let callCluster = sinon.stub();
+    const searchMock = sinon.stub();
+    const callCluster = ({ search: searchMock } as unknown) as ElasticsearchClient;
 
     beforeEach(() => {
       const getStub = { get: sinon.stub() };
       getStub.get.withArgs('xpack.monitoring.beats.index_pattern').returns('beats-indices-*');
-      callCluster = sinon.stub();
+      searchMock.reset();
     });
 
     it('should set `from: 0, to: 10000` in the query', async () => {
+      searchMock.returns(Promise.resolve({ body: {} }));
       await fetchBeatsStats(callCluster, clusterUuids, start, end, {} as any);
-      const { args } = callCluster.firstCall;
-      const [api, { body }] = args;
+      const { args } = searchMock.firstCall;
+      const [{ body }] = args;
 
-      expect(api).toEqual('search');
       expect(body.from).toEqual(0);
       expect(body.size).toEqual(10000);
     });
 
     it('should set `from: 10000, from: 10000` in the query', async () => {
+      searchMock.returns(Promise.resolve({ body: {} }));
       await fetchBeatsStats(callCluster, clusterUuids, start, end, { page: 1 } as any);
-      const { args } = callCluster.firstCall;
-      const [api, { body }] = args;
+      const { args } = searchMock.firstCall;
+      const [{ body }] = args;
 
-      expect(api).toEqual('search');
       expect(body.from).toEqual(10000);
       expect(body.size).toEqual(10000);
     });
 
     it('should set `from: 20000, from: 10000` in the query', async () => {
+      searchMock.returns(Promise.resolve({ body: {} }));
       await fetchBeatsStats(callCluster, clusterUuids, start, end, { page: 2 } as any);
-      const { args } = callCluster.firstCall;
-      const [api, { body }] = args;
+      const { args } = searchMock.firstCall;
+      const [{ body }] = args;
 
-      expect(api).toEqual('search');
       expect(body.from).toEqual(20000);
       expect(body.size).toEqual(10000);
     });
diff --git a/x-pack/plugins/monitoring/server/telemetry_collection/get_beats_stats.ts b/x-pack/plugins/monitoring/server/telemetry_collection/get_beats_stats.ts
index ba83584e346545..c62fbf4e8a1cfb 100644
--- a/x-pack/plugins/monitoring/server/telemetry_collection/get_beats_stats.ts
+++ b/x-pack/plugins/monitoring/server/telemetry_collection/get_beats_stats.ts
@@ -7,7 +7,8 @@
 
 import { get } from 'lodash';
 import { SearchResponse } from 'elasticsearch';
-import { LegacyAPICaller } from 'kibana/server';
+import { ElasticsearchClient } from 'kibana/server';
+import { estypes } from '@elastic/elasticsearch';
 import { createQuery } from './create_query';
 import { INDEX_PATTERN_BEATS } from '../../common/constants';
 
@@ -319,17 +320,17 @@ export function processResults(
  * @return {Promise}
  */
 async function fetchBeatsByType(
-  callCluster: LegacyAPICaller,
+  callCluster: ElasticsearchClient,
   clusterUuids: string[],
   start: string,
   end: string,
   { page = 0, ...options }: { page?: number } & BeatsProcessOptions,
   type: string
 ): Promise<void> {
-  const params = {
+  const params: estypes.SearchRequest = {
     index: INDEX_PATTERN_BEATS,
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       'hits.hits._source.cluster_uuid',
       'hits.hits._source.type',
       'hits.hits._source.beats_stats.beat.version',
@@ -353,7 +354,7 @@ async function fetchBeatsByType(
             },
           },
         ],
-      }),
+      }) as estypes.QueryDslQueryContainer,
       from: page * HITS_SIZE,
       collapse: { field: `${type}.beat.uuid` },
       sort: [{ [`${type}.timestamp`]: { order: 'desc', unmapped_type: 'long' } }],
@@ -361,11 +362,11 @@ async function fetchBeatsByType(
     },
   };
 
-  const results = await callCluster<SearchResponse<BeatsStats>>('search', params);
+  const { body: results } = await callCluster.search(params);
   const hitsLength = results?.hits?.hits.length || 0;
   if (hitsLength > 0) {
     // further augment the clusters object with more stats
-    processResults(results, options);
+    processResults(results as SearchResponse<BeatsStats>, options);
 
     if (hitsLength === HITS_SIZE) {
       // call recursively
@@ -383,7 +384,7 @@ async function fetchBeatsByType(
 }
 
 export async function fetchBeatsStats(
-  callCluster: LegacyAPICaller,
+  callCluster: ElasticsearchClient,
   clusterUuids: string[],
   start: string,
   end: string,
@@ -393,7 +394,7 @@ export async function fetchBeatsStats(
 }
 
 export async function fetchBeatsStates(
-  callCluster: LegacyAPICaller,
+  callCluster: ElasticsearchClient,
   clusterUuids: string[],
   start: string,
   end: string,
@@ -411,7 +412,7 @@ export interface BeatsStatsByClusterUuid {
  * @return {Object} - Beats stats in an object keyed by the cluster UUIDs
  */
 export async function getBeatsStats(
-  callCluster: LegacyAPICaller,
+  callCluster: ElasticsearchClient,
   clusterUuids: string[],
   start: string,
   end: string
diff --git a/x-pack/plugins/monitoring/server/telemetry_collection/get_cluster_uuids.test.ts b/x-pack/plugins/monitoring/server/telemetry_collection/get_cluster_uuids.test.ts
index 07d623867bc1c6..7e7ec23b69daf3 100644
--- a/x-pack/plugins/monitoring/server/telemetry_collection/get_cluster_uuids.test.ts
+++ b/x-pack/plugins/monitoring/server/telemetry_collection/get_cluster_uuids.test.ts
@@ -5,6 +5,7 @@
  * 2.0.
  */
 
+import { ElasticsearchClient } from 'kibana/server';
 import sinon from 'sinon';
 import {
   getClusterUuids,
@@ -13,40 +14,52 @@ import {
 } from './get_cluster_uuids';
 
 describe('get_cluster_uuids', () => {
-  const callCluster = sinon.stub();
+  const searchMock = sinon.stub();
+  const callCluster = ({ search: searchMock } as unknown) as ElasticsearchClient;
+
+  afterEach(() => {
+    searchMock.reset();
+  });
+
   const response = {
-    aggregations: {
-      cluster_uuids: {
-        buckets: [{ key: 'abc' }, { key: 'xyz' }, { key: '123' }],
+    body: {
+      aggregations: {
+        cluster_uuids: {
+          buckets: [{ key: 'abc' }, { key: 'xyz' }, { key: '123' }],
+        },
       },
     },
   };
-  const expectedUuids = response.aggregations.cluster_uuids.buckets.map((bucket) => bucket.key);
+
+  const expectedUuids = response.body.aggregations.cluster_uuids.buckets.map(
+    (bucket) => bucket.key
+  );
+
   const timestamp = Date.now();
 
   describe('getClusterUuids', () => {
     it('returns cluster UUIDs', async () => {
-      callCluster.withArgs('search').returns(Promise.resolve(response));
+      searchMock.returns(Promise.resolve(response));
       expect(await getClusterUuids(callCluster, timestamp, 1)).toStrictEqual(expectedUuids);
     });
   });
 
   describe('fetchClusterUuids', () => {
     it('searches for clusters', async () => {
-      callCluster.returns(Promise.resolve(response));
-      expect(await fetchClusterUuids(callCluster, timestamp, 1)).toStrictEqual(response);
+      searchMock.returns(Promise.resolve(response));
+      expect(await fetchClusterUuids(callCluster, timestamp, 1)).toStrictEqual(response.body);
     });
   });
 
   describe('handleClusterUuidsResponse', () => {
-    // filterPath makes it easy to ignore anything unexpected because it will come back empty
+    // filter_path makes it easy to ignore anything unexpected because it will come back empty
     it('handles unexpected response', () => {
       const clusterUuids = handleClusterUuidsResponse({});
       expect(clusterUuids.length).toStrictEqual(0);
     });
 
     it('handles valid response', () => {
-      const clusterUuids = handleClusterUuidsResponse(response);
+      const clusterUuids = handleClusterUuidsResponse(response.body);
       expect(clusterUuids).toStrictEqual(expectedUuids);
     });
 
diff --git a/x-pack/plugins/monitoring/server/telemetry_collection/get_cluster_uuids.ts b/x-pack/plugins/monitoring/server/telemetry_collection/get_cluster_uuids.ts
index db7a031385b4a7..7cf4ca2b94ce01 100644
--- a/x-pack/plugins/monitoring/server/telemetry_collection/get_cluster_uuids.ts
+++ b/x-pack/plugins/monitoring/server/telemetry_collection/get_cluster_uuids.ts
@@ -7,7 +7,8 @@
 
 import { get } from 'lodash';
 import moment from 'moment';
-import { LegacyAPICaller } from 'kibana/server';
+import { ElasticsearchClient } from 'kibana/server';
+import { estypes } from '@elastic/elasticsearch';
 import { createQuery } from './create_query';
 import {
   INDEX_PATTERN_ELASTICSEARCH,
@@ -18,7 +19,7 @@ import {
  * Get a list of Cluster UUIDs that exist within the specified timespan.
  */
 export async function getClusterUuids(
-  callCluster: LegacyAPICaller, // TODO: To be changed to the new ES client when the plugin migrates
+  callCluster: ElasticsearchClient,
   timestamp: number,
   maxBucketSize: number
 ) {
@@ -30,7 +31,7 @@ export async function getClusterUuids(
  * Fetch the aggregated Cluster UUIDs from the monitoring cluster.
  */
 export async function fetchClusterUuids(
-  callCluster: LegacyAPICaller,
+  callCluster: ElasticsearchClient,
   timestamp: number,
   maxBucketSize: number
 ) {
@@ -38,13 +39,13 @@ export async function fetchClusterUuids(
 
   const end = moment(timestamp).toISOString();
 
-  const params = {
+  const params: estypes.SearchRequest = {
     index: INDEX_PATTERN_ELASTICSEARCH,
     size: 0,
-    ignoreUnavailable: true,
-    filterPath: 'aggregations.cluster_uuids.buckets.key',
+    ignore_unavailable: true,
+    filter_path: 'aggregations.cluster_uuids.buckets.key',
     body: {
-      query: createQuery({ type: 'cluster_stats', start, end }),
+      query: createQuery({ type: 'cluster_stats', start, end }) as estypes.QueryDslQueryContainer,
       aggs: {
         cluster_uuids: {
           terms: {
@@ -56,7 +57,8 @@ export async function fetchClusterUuids(
     },
   };
 
-  return await callCluster('search', params);
+  const { body: response } = await callCluster.search(params);
+  return response;
 }
 
 /**
diff --git a/x-pack/plugins/monitoring/server/telemetry_collection/get_es_stats.test.ts b/x-pack/plugins/monitoring/server/telemetry_collection/get_es_stats.test.ts
index 033b3ebffe5f16..3b5f654be42223 100644
--- a/x-pack/plugins/monitoring/server/telemetry_collection/get_es_stats.test.ts
+++ b/x-pack/plugins/monitoring/server/telemetry_collection/get_es_stats.test.ts
@@ -5,6 +5,7 @@
  * 2.0.
  */
 
+import { ElasticsearchClient } from 'kibana/server';
 import sinon from 'sinon';
 import {
   fetchElasticsearchStats,
@@ -13,8 +14,9 @@ import {
 } from './get_es_stats';
 
 describe('get_es_stats', () => {
-  const callWith = sinon.stub();
-  const response = {
+  const searchMock = sinon.stub();
+  const client = ({ search: searchMock } as unknown) as ElasticsearchClient;
+  const body = {
     hits: {
       hits: [
         { _id: 'abc', _source: { cluster_uuid: 'abc' } },
@@ -23,15 +25,15 @@ describe('get_es_stats', () => {
       ],
     },
   };
-  const expectedClusters = response.hits.hits.map((hit) => hit._source);
+  const expectedClusters = body.hits.hits.map((hit) => hit._source);
   const clusterUuids = expectedClusters.map((cluster) => cluster.cluster_uuid);
   const maxBucketSize = 1;
 
   describe('getElasticsearchStats', () => {
     it('returns clusters', async () => {
-      callWith.withArgs('search').returns(Promise.resolve(response));
+      searchMock.returns(Promise.resolve({ body }));
 
-      expect(await getElasticsearchStats(callWith, clusterUuids, maxBucketSize)).toStrictEqual(
+      expect(await getElasticsearchStats(client, clusterUuids, maxBucketSize)).toStrictEqual(
         expectedClusters
       );
     });
@@ -39,16 +41,16 @@ describe('get_es_stats', () => {
 
   describe('fetchElasticsearchStats', () => {
     it('searches for clusters', async () => {
-      callWith.returns(response);
+      searchMock.returns({ body });
 
-      expect(await fetchElasticsearchStats(callWith, clusterUuids, maxBucketSize)).toStrictEqual(
-        response
+      expect(await fetchElasticsearchStats(client, clusterUuids, maxBucketSize)).toStrictEqual(
+        body
       );
     });
   });
 
   describe('handleElasticsearchStats', () => {
-    // filterPath makes it easy to ignore anything unexpected because it will come back empty
+    // filter_path makes it easy to ignore anything unexpected because it will come back empty
     it('handles unexpected response', () => {
       const clusters = handleElasticsearchStats({} as any);
 
@@ -56,7 +58,7 @@ describe('get_es_stats', () => {
     });
 
     it('handles valid response', () => {
-      const clusters = handleElasticsearchStats(response as any);
+      const clusters = handleElasticsearchStats(body as any);
 
       expect(clusters).toStrictEqual(expectedClusters);
     });
diff --git a/x-pack/plugins/monitoring/server/telemetry_collection/get_es_stats.ts b/x-pack/plugins/monitoring/server/telemetry_collection/get_es_stats.ts
index f309e01c961187..217ab70ab0ecaa 100644
--- a/x-pack/plugins/monitoring/server/telemetry_collection/get_es_stats.ts
+++ b/x-pack/plugins/monitoring/server/telemetry_collection/get_es_stats.ts
@@ -6,7 +6,8 @@
  */
 
 import { SearchResponse } from 'elasticsearch';
-import { LegacyAPICaller } from 'kibana/server';
+import { ElasticsearchClient } from 'kibana/server';
+import { estypes } from '@elastic/elasticsearch';
 import { INDEX_PATTERN_ELASTICSEARCH } from '../../common/constants';
 
 /**
@@ -17,7 +18,7 @@ import { INDEX_PATTERN_ELASTICSEARCH } from '../../common/constants';
  * @param {Array} clusterUuids The string Cluster UUIDs to fetch details for
  */
 export async function getElasticsearchStats(
-  callCluster: LegacyAPICaller,
+  callCluster: ElasticsearchClient,
   clusterUuids: string[],
   maxBucketSize: number
 ) {
@@ -34,16 +35,16 @@ export async function getElasticsearchStats(
  *
  * Returns the response for the aggregations to fetch details for the product.
  */
-export function fetchElasticsearchStats(
-  callCluster: LegacyAPICaller,
+export async function fetchElasticsearchStats(
+  callCluster: ElasticsearchClient,
   clusterUuids: string[],
   maxBucketSize: number
 ) {
-  const params = {
+  const params: estypes.SearchRequest = {
     index: INDEX_PATTERN_ELASTICSEARCH,
     size: maxBucketSize,
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       'hits.hits._source.cluster_uuid',
       'hits.hits._source.timestamp',
       'hits.hits._source.cluster_name',
@@ -69,7 +70,8 @@ export function fetchElasticsearchStats(
     },
   };
 
-  return callCluster('search', params);
+  const { body: response } = await callCluster.search(params);
+  return response as SearchResponse<ESClusterStats>;
 }
 
 export interface ESClusterStats {
diff --git a/x-pack/plugins/monitoring/server/telemetry_collection/get_high_level_stats.test.ts b/x-pack/plugins/monitoring/server/telemetry_collection/get_high_level_stats.test.ts
index e2eed7381f4511..00a14f7b12f7ed 100644
--- a/x-pack/plugins/monitoring/server/telemetry_collection/get_high_level_stats.test.ts
+++ b/x-pack/plugins/monitoring/server/telemetry_collection/get_high_level_stats.test.ts
@@ -5,6 +5,7 @@
  * 2.0.
  */
 
+import { ElasticsearchClient } from 'kibana/server';
 import sinon from 'sinon';
 import {
   fetchHighLevelStats,
@@ -13,12 +14,13 @@ import {
 } from './get_high_level_stats';
 
 describe('get_high_level_stats', () => {
-  const callWith = sinon.stub();
+  const searchMock = sinon.stub();
+  const callCluster = ({ search: searchMock } as unknown) as ElasticsearchClient;
   const product = 'xyz';
   const cloudName = 'bare-metal';
   const start = new Date().toISOString();
   const end = new Date().toISOString();
-  const response = {
+  const body = {
     hits: {
       hits: [
         {
@@ -232,26 +234,26 @@ describe('get_high_level_stats', () => {
 
   describe('getHighLevelStats', () => {
     it('returns clusters', async () => {
-      callWith.withArgs('search').returns(Promise.resolve(response));
+      searchMock.returns(Promise.resolve({ body }));
 
       expect(
-        await getHighLevelStats(callWith, clusterUuids, start, end, product, maxBucketSize)
+        await getHighLevelStats(callCluster, clusterUuids, start, end, product, maxBucketSize)
       ).toStrictEqual(expectedClusters);
     });
   });
 
   describe('fetchHighLevelStats', () => {
     it('searches for clusters', async () => {
-      callWith.returns(Promise.resolve(response));
+      searchMock.returns(Promise.resolve({ body }));
 
       expect(
-        await fetchHighLevelStats(callWith, clusterUuids, start, end, product, maxBucketSize)
-      ).toStrictEqual(response);
+        await fetchHighLevelStats(callCluster, clusterUuids, start, end, product, maxBucketSize)
+      ).toStrictEqual(body);
     });
   });
 
   describe('handleHighLevelStatsResponse', () => {
-    // filterPath makes it easy to ignore anything unexpected because it will come back empty
+    // filter_path makes it easy to ignore anything unexpected because it will come back empty
     it('handles unexpected response', () => {
       const clusters = handleHighLevelStatsResponse({} as any, product);
 
@@ -259,7 +261,7 @@ describe('get_high_level_stats', () => {
     });
 
     it('handles valid response', () => {
-      const clusters = handleHighLevelStatsResponse(response as any, product);
+      const clusters = handleHighLevelStatsResponse(body as any, product);
 
       expect(clusters).toStrictEqual(expectedClusters);
     });
diff --git a/x-pack/plugins/monitoring/server/telemetry_collection/get_high_level_stats.ts b/x-pack/plugins/monitoring/server/telemetry_collection/get_high_level_stats.ts
index 63188be142fdd6..2fb3814ac40224 100644
--- a/x-pack/plugins/monitoring/server/telemetry_collection/get_high_level_stats.ts
+++ b/x-pack/plugins/monitoring/server/telemetry_collection/get_high_level_stats.ts
@@ -7,7 +7,8 @@
 
 import { get } from 'lodash';
 import { SearchResponse } from 'elasticsearch';
-import { LegacyAPICaller } from 'kibana/server';
+import { ElasticsearchClient } from 'kibana/server';
+import { estypes } from '@elastic/elasticsearch';
 import { createQuery } from './create_query';
 import {
   INDEX_PATTERN_KIBANA,
@@ -248,7 +249,7 @@ function getIndexPatternForStackProduct(product: string) {
  * Returns an object keyed by the cluster UUIDs to make grouping easier.
  */
 export async function getHighLevelStats(
-  callCluster: LegacyAPICaller,
+  callCluster: ElasticsearchClient,
   clusterUuids: string[],
   start: string,
   end: string,
@@ -269,7 +270,7 @@ export async function getHighLevelStats(
 export async function fetchHighLevelStats<
   T extends { cluster_uuid?: string } = { cluster_uuid?: string }
 >(
-  callCluster: LegacyAPICaller,
+  callCluster: ElasticsearchClient,
   clusterUuids: string[],
   start: string,
   end: string,
@@ -300,14 +301,11 @@ export async function fetchHighLevelStats<
     filters.push(kibanaFilter);
   }
 
-  const params = {
-    index: getIndexPatternForStackProduct(product),
+  const params: estypes.SearchRequest = {
+    index: getIndexPatternForStackProduct(product) as string,
     size: maxBucketSize,
-    headers: {
-      'X-QUERY-SOURCE': TELEMETRY_QUERY_SOURCE,
-    },
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       'hits.hits._source.cluster_uuid',
       `hits.hits._source.${product}_stats.${product}.version`,
       `hits.hits._source.${product}_stats.os`,
@@ -325,7 +323,7 @@ export async function fetchHighLevelStats<
         end,
         type: `${product}_stats`,
         filters,
-      }),
+      }) as estypes.QueryDslQueryContainer,
       collapse: {
         // a more ideal field would be the concatenation of the uuid + transport address for duped UUIDs (copied installations)
         field: `${product}_stats.${product}.uuid`,
@@ -334,7 +332,12 @@ export async function fetchHighLevelStats<
     },
   };
 
-  return callCluster('search', params);
+  const { body: response } = await callCluster.search(params, {
+    headers: {
+      'X-QUERY-SOURCE': TELEMETRY_QUERY_SOURCE,
+    },
+  });
+  return response as SearchResponse<T>;
 }
 
 /**
diff --git a/x-pack/plugins/monitoring/server/telemetry_collection/get_kibana_stats.ts b/x-pack/plugins/monitoring/server/telemetry_collection/get_kibana_stats.ts
index 59a77bd7a6b4c0..4be5e02dff3a66 100644
--- a/x-pack/plugins/monitoring/server/telemetry_collection/get_kibana_stats.ts
+++ b/x-pack/plugins/monitoring/server/telemetry_collection/get_kibana_stats.ts
@@ -8,7 +8,7 @@
 import moment from 'moment';
 import { isEmpty } from 'lodash';
 import { SearchResponse } from 'elasticsearch';
-import { LegacyAPICaller } from 'kibana/server';
+import { ElasticsearchClient } from 'kibana/server';
 import { KIBANA_SYSTEM_ID, TELEMETRY_COLLECTION_INTERVAL } from '../../common/constants';
 import {
   fetchHighLevelStats,
@@ -183,7 +183,7 @@ export function ensureTimeSpan(
  * specialized usage data that comes with kibana stats (kibana_stats.usage).
  */
 export async function getKibanaStats(
-  callCluster: LegacyAPICaller,
+  callCluster: ElasticsearchClient,
   clusterUuids: string[],
   start: string,
   end: string,
diff --git a/x-pack/plugins/monitoring/server/telemetry_collection/get_licenses.test.ts b/x-pack/plugins/monitoring/server/telemetry_collection/get_licenses.test.ts
index ce4bf523b3e1ae..98f1daf57a85a6 100644
--- a/x-pack/plugins/monitoring/server/telemetry_collection/get_licenses.test.ts
+++ b/x-pack/plugins/monitoring/server/telemetry_collection/get_licenses.test.ts
@@ -5,12 +5,14 @@
  * 2.0.
  */
 
+import { ElasticsearchClient } from 'kibana/server';
 import sinon from 'sinon';
 import { getLicenses, handleLicenses, fetchLicenses } from './get_licenses';
 
 describe('get_licenses', () => {
-  const callWith = sinon.stub();
-  const response = {
+  const searchMock = sinon.stub();
+  const client = ({ search: searchMock } as unknown) as ElasticsearchClient;
+  const body = {
     hits: {
       hits: [
         { _id: 'abc', _source: { cluster_uuid: 'abc', license: { type: 'basic' } } },
@@ -19,7 +21,7 @@ describe('get_licenses', () => {
       ],
     },
   };
-  const expectedClusters = response.hits.hits.map((hit) => hit._source);
+  const expectedClusters = body.hits.hits.map((hit) => hit._source);
   const clusterUuids = expectedClusters.map((cluster) => cluster.cluster_uuid);
   const expectedLicenses = {
     abc: { type: 'basic' },
@@ -29,22 +31,22 @@ describe('get_licenses', () => {
 
   describe('getLicenses', () => {
     it('returns clusters', async () => {
-      callWith.withArgs('search').returns(Promise.resolve(response));
+      searchMock.returns(Promise.resolve({ body }));
 
-      expect(await getLicenses(clusterUuids, callWith, 1)).toStrictEqual(expectedLicenses);
+      expect(await getLicenses(clusterUuids, client, 1)).toStrictEqual(expectedLicenses);
     });
   });
 
   describe('fetchLicenses', () => {
     it('searches for clusters', async () => {
-      callWith.returns(response);
+      searchMock.returns({ body });
 
-      expect(await fetchLicenses(callWith, clusterUuids, 1)).toStrictEqual(response);
+      expect(await fetchLicenses(client, clusterUuids, 1)).toStrictEqual(body);
     });
   });
 
   describe('handleLicenses', () => {
-    // filterPath makes it easy to ignore anything unexpected because it will come back empty
+    // filter_path makes it easy to ignore anything unexpected because it will come back empty
     it('handles unexpected response', () => {
       const clusters = handleLicenses({} as any);
 
@@ -52,7 +54,7 @@ describe('get_licenses', () => {
     });
 
     it('handles valid response', () => {
-      const clusters = handleLicenses(response as any);
+      const clusters = handleLicenses(body as any);
 
       expect(clusters).toStrictEqual(expectedLicenses);
     });
diff --git a/x-pack/plugins/monitoring/server/telemetry_collection/get_licenses.ts b/x-pack/plugins/monitoring/server/telemetry_collection/get_licenses.ts
index 3115e2adbdad27..633e37a2049bdd 100644
--- a/x-pack/plugins/monitoring/server/telemetry_collection/get_licenses.ts
+++ b/x-pack/plugins/monitoring/server/telemetry_collection/get_licenses.ts
@@ -6,7 +6,8 @@
  */
 
 import { SearchResponse } from 'elasticsearch';
-import { LegacyAPICaller } from 'kibana/server';
+import { ElasticsearchClient } from 'kibana/server';
+import { estypes } from '@elastic/elasticsearch';
 import { ESLicense } from '../../../telemetry_collection_xpack/server';
 import { INDEX_PATTERN_ELASTICSEARCH } from '../../common/constants';
 
@@ -15,7 +16,7 @@ import { INDEX_PATTERN_ELASTICSEARCH } from '../../common/constants';
  */
 export async function getLicenses(
   clusterUuids: string[],
-  callCluster: LegacyAPICaller, // TODO: To be changed to the new ES client when the plugin migrates
+  callCluster: ElasticsearchClient, // TODO: To be changed to the new ES client when the plugin migrates
   maxBucketSize: number
 ): Promise<{ [clusterUuid: string]: ESLicense | undefined }> {
   const response = await fetchLicenses(callCluster, clusterUuids, maxBucketSize);
@@ -31,16 +32,16 @@ export async function getLicenses(
  *
  * Returns the response for the aggregations to fetch details for the product.
  */
-export function fetchLicenses(
-  callCluster: LegacyAPICaller,
+export async function fetchLicenses(
+  callCluster: ElasticsearchClient,
   clusterUuids: string[],
   maxBucketSize: number
 ) {
-  const params = {
+  const params: estypes.SearchRequest = {
     index: INDEX_PATTERN_ELASTICSEARCH,
     size: maxBucketSize,
-    ignoreUnavailable: true,
-    filterPath: ['hits.hits._source.cluster_uuid', 'hits.hits._source.license'],
+    ignore_unavailable: true,
+    filter_path: ['hits.hits._source.cluster_uuid', 'hits.hits._source.license'],
     body: {
       query: {
         bool: {
@@ -59,7 +60,8 @@ export function fetchLicenses(
     },
   };
 
-  return callCluster('search', params);
+  const { body: response } = await callCluster.search(params);
+  return response as SearchResponse<ESClusterStatsWithLicense>;
 }
 
 export interface ESClusterStatsWithLicense {
diff --git a/x-pack/plugins/monitoring/server/telemetry_collection/get_logstash_stats.test.ts b/x-pack/plugins/monitoring/server/telemetry_collection/get_logstash_stats.test.ts
index cf1574f8d3f0ee..cd77d28f6c430d 100644
--- a/x-pack/plugins/monitoring/server/telemetry_collection/get_logstash_stats.test.ts
+++ b/x-pack/plugins/monitoring/server/telemetry_collection/get_logstash_stats.test.ts
@@ -12,6 +12,7 @@ import {
   processLogstashStateResults,
 } from './get_logstash_stats';
 import sinon from 'sinon';
+import { ElasticsearchClient } from 'kibana/server';
 
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const logstashStatsResultSet = require('./__mocks__/fixtures/logstash_stats_results');
@@ -33,10 +34,15 @@ const getBaseOptions = () => ({
 
 describe('Get Logstash Stats', () => {
   const clusterUuids = ['aCluster', 'bCluster', 'cCluster'];
-  let callCluster = sinon.stub();
+  const searchMock = sinon.stub();
+  const callCluster = ({ search: searchMock } as unknown) as ElasticsearchClient;
 
   beforeEach(() => {
-    callCluster = sinon.stub();
+    searchMock.returns(Promise.resolve({ body: {} }));
+  });
+
+  afterEach(() => {
+    searchMock.reset();
   });
 
   describe('fetchLogstashState', () => {
@@ -63,17 +69,15 @@ describe('Get Logstash Stats', () => {
       };
 
       await fetchLogstashState(callCluster, clusterUuid, ephemeralIds, {} as any);
-      const { args } = callCluster.firstCall;
-      const [api, { body }] = args;
-      expect(api).toEqual('search');
+      const { args } = searchMock.firstCall;
+      const [{ body }] = args;
       expect(body.query).toEqual(expected);
     });
 
     it('should set `from: 0, to: 10000` in the query', async () => {
       await fetchLogstashState(callCluster, clusterUuid, ephemeralIds, {} as any);
-      const { args } = callCluster.firstCall;
-      const [api, { body }] = args;
-      expect(api).toEqual('search');
+      const { args } = searchMock.firstCall;
+      const [{ body }] = args;
       expect(body.from).toEqual(0);
       expect(body.size).toEqual(10000);
     });
@@ -82,10 +86,9 @@ describe('Get Logstash Stats', () => {
       await fetchLogstashState(callCluster, clusterUuid, ephemeralIds, {
         page: 1,
       } as any);
-      const { args } = callCluster.firstCall;
-      const [api, { body }] = args;
+      const { args } = searchMock.firstCall;
+      const [{ body }] = args;
 
-      expect(api).toEqual('search');
       expect(body.from).toEqual(10000);
       expect(body.size).toEqual(10000);
     });
@@ -94,10 +97,9 @@ describe('Get Logstash Stats', () => {
       await fetchLogstashState(callCluster, clusterUuid, ephemeralIds, {
         page: 2,
       } as any);
-      const { args } = callCluster.firstCall;
-      const [api, { body }] = args;
+      const { args } = searchMock.firstCall;
+      const [{ body }] = args;
 
-      expect(api).toEqual('search');
       expect(body.from).toEqual(20000);
       expect(body.size).toEqual(10000);
     });
@@ -106,30 +108,27 @@ describe('Get Logstash Stats', () => {
   describe('fetchLogstashStats', () => {
     it('should set `from: 0, to: 10000` in the query', async () => {
       await fetchLogstashStats(callCluster, clusterUuids, {} as any);
-      const { args } = callCluster.firstCall;
-      const [api, { body }] = args;
+      const { args } = searchMock.firstCall;
+      const [{ body }] = args;
 
-      expect(api).toEqual('search');
       expect(body.from).toEqual(0);
       expect(body.size).toEqual(10000);
     });
 
     it('should set `from: 10000, to: 10000` in the query', async () => {
       await fetchLogstashStats(callCluster, clusterUuids, { page: 1 } as any);
-      const { args } = callCluster.firstCall;
-      const [api, { body }] = args;
+      const { args } = searchMock.firstCall;
+      const [{ body }] = args;
 
-      expect(api).toEqual('search');
       expect(body.from).toEqual(10000);
       expect(body.size).toEqual(10000);
     });
 
     it('should set `from: 20000, to: 10000` in the query', async () => {
       await fetchLogstashStats(callCluster, clusterUuids, { page: 2 } as any);
-      const { args } = callCluster.firstCall;
-      const [api, { body }] = args;
+      const { args } = searchMock.firstCall;
+      const [{ body }] = args;
 
-      expect(api).toEqual('search');
       expect(body.from).toEqual(20000);
       expect(body.size).toEqual(10000);
     });
diff --git a/x-pack/plugins/monitoring/server/telemetry_collection/get_logstash_stats.ts b/x-pack/plugins/monitoring/server/telemetry_collection/get_logstash_stats.ts
index fafb52d6862b55..ac3f5fceb47ade 100644
--- a/x-pack/plugins/monitoring/server/telemetry_collection/get_logstash_stats.ts
+++ b/x-pack/plugins/monitoring/server/telemetry_collection/get_logstash_stats.ts
@@ -6,7 +6,8 @@
  */
 
 import { SearchResponse } from 'elasticsearch';
-import { LegacyAPICaller } from 'kibana/server';
+import { ElasticsearchClient } from 'kibana/server';
+import { estypes } from '@elastic/elasticsearch';
 import { createQuery } from './create_query';
 import { mapToList } from './get_high_level_stats';
 import { incrementByKey } from './get_high_level_stats';
@@ -261,17 +262,14 @@ export function processLogstashStateResults(
 }
 
 export async function fetchLogstashStats(
-  callCluster: LegacyAPICaller,
+  callCluster: ElasticsearchClient,
   clusterUuids: string[],
   { page = 0, ...options }: { page?: number } & LogstashProcessOptions
 ): Promise<void> {
-  const params = {
-    headers: {
-      'X-QUERY-SOURCE': TELEMETRY_QUERY_SOURCE,
-    },
+  const params: estypes.SearchRequest = {
     index: INDEX_PATTERN_LOGSTASH,
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       'hits.hits._source.cluster_uuid',
       'hits.hits._source.type',
       'hits.hits._source.source_node',
@@ -295,7 +293,7 @@ export async function fetchLogstashStats(
             },
           },
         ],
-      }),
+      }) as estypes.QueryDslQueryContainer,
       from: page * HITS_SIZE,
       collapse: { field: 'logstash_stats.logstash.uuid' },
       sort: [{ ['logstash_stats.timestamp']: { order: 'desc', unmapped_type: 'long' } }],
@@ -303,12 +301,16 @@ export async function fetchLogstashStats(
     },
   };
 
-  const results = await callCluster<SearchResponse<LogstashStats>>('search', params);
+  const { body: results } = await callCluster.search(params, {
+    headers: {
+      'X-QUERY-SOURCE': TELEMETRY_QUERY_SOURCE,
+    },
+  });
   const hitsLength = results?.hits?.hits.length || 0;
 
   if (hitsLength > 0) {
     // further augment the clusters object with more stats
-    processStatsResults(results, options);
+    processStatsResults(results as SearchResponse<LogstashStats>, options);
 
     if (hitsLength === HITS_SIZE) {
       // call recursively
@@ -325,18 +327,15 @@ export async function fetchLogstashStats(
 }
 
 export async function fetchLogstashState(
-  callCluster: LegacyAPICaller,
+  callCluster: ElasticsearchClient,
   clusterUuid: string,
   ephemeralIds: string[],
   { page = 0, ...options }: { page?: number } & LogstashProcessOptions
 ): Promise<void> {
-  const params = {
-    headers: {
-      'X-QUERY-SOURCE': TELEMETRY_QUERY_SOURCE,
-    },
+  const params: estypes.SearchRequest = {
     index: INDEX_PATTERN_LOGSTASH,
-    ignoreUnavailable: true,
-    filterPath: [
+    ignore_unavailable: true,
+    filter_path: [
       'hits.hits._source.logstash_state.pipeline.batch_size',
       'hits.hits._source.logstash_state.pipeline.workers',
       'hits.hits._source.logstash_state.pipeline.representation.graph.vertices.config_name',
@@ -355,7 +354,7 @@ export async function fetchLogstashState(
             },
           },
         ],
-      }),
+      }) as estypes.QueryDslQueryContainer,
       from: page * HITS_SIZE,
       collapse: { field: 'logstash_state.pipeline.ephemeral_id' },
       sort: [{ ['timestamp']: { order: 'desc', unmapped_type: 'long' } }],
@@ -363,11 +362,16 @@ export async function fetchLogstashState(
     },
   };
 
-  const results = await callCluster<SearchResponse<LogstashState>>('search', params);
+  const { body: results } = await callCluster.search<SearchResponse<LogstashState>>(params, {
+    headers: {
+      'X-QUERY-SOURCE': TELEMETRY_QUERY_SOURCE,
+    },
+  });
+
   const hitsLength = results?.hits?.hits.length || 0;
   if (hitsLength > 0) {
     // further augment the clusters object with more stats
-    processLogstashStateResults(results, clusterUuid, options);
+    processLogstashStateResults(results as SearchResponse<LogstashState>, clusterUuid, options);
 
     if (hitsLength === HITS_SIZE) {
       // call recursively
@@ -392,7 +396,7 @@ export interface LogstashStatsByClusterUuid {
  * @return {Object} - Logstash stats in an object keyed by the cluster UUIDs
  */
 export async function getLogstashStats(
-  callCluster: LegacyAPICaller,
+  callCluster: ElasticsearchClient,
   clusterUuids: string[]
 ): Promise<LogstashStatsByClusterUuid> {
   const options: LogstashProcessOptions = {
diff --git a/x-pack/plugins/monitoring/server/telemetry_collection/register_monitoring_telemetry_collection.ts b/x-pack/plugins/monitoring/server/telemetry_collection/register_monitoring_telemetry_collection.ts
index 23c61393899170..bb5d379f3c80c4 100644
--- a/x-pack/plugins/monitoring/server/telemetry_collection/register_monitoring_telemetry_collection.ts
+++ b/x-pack/plugins/monitoring/server/telemetry_collection/register_monitoring_telemetry_collection.ts
@@ -5,7 +5,7 @@
  * 2.0.
  */
 
-import type { ILegacyClusterClient } from 'kibana/server';
+import type { IClusterClient } from 'kibana/server';
 import type { UsageCollectionSetup } from 'src/plugins/usage_collection/server';
 import type { UsageStatsPayload } from '../../../../../src/plugins/telemetry_collection_manager/server';
 import type { LogstashBaseStats } from './get_logstash_stats';
@@ -31,7 +31,7 @@ interface MonitoringTelemetryUsage {
 
 export function registerMonitoringTelemetryCollection(
   usageCollection: UsageCollectionSetup,
-  legacyEsClient: ILegacyClusterClient,
+  getClient: () => IClusterClient,
   maxBucketSize: number
 ) {
   const monitoringStatsCollector = usageCollection.makeStatsCollector<
@@ -137,15 +137,13 @@ export function registerMonitoringTelemetryCollection(
         },
       },
     },
-    fetch: async ({ kibanaRequest }) => {
+    fetch: async ({ kibanaRequest, esClient }) => {
       const timestamp = Date.now(); // Collect the telemetry from the monitoring indices for this moment.
       // NOTE: Usually, the monitoring indices index stats for each product every 10s (by default).
       // However, some data may be delayed up-to 24h because monitoring only collects extended Kibana stats in that interval
       // to avoid overloading of the system when retrieving data from the collectors (that delay is dealt with in the Kibana Stats getter inside the `getAllStats` method).
       // By 8.x, we expect to stop collecting the Kibana extended stats and keep only the monitoring-related metrics.
-      const callCluster = kibanaRequest
-        ? legacyEsClient.asScoped(kibanaRequest).callAsCurrentUser
-        : legacyEsClient.callAsInternalUser;
+      const callCluster = kibanaRequest ? esClient : getClient().asInternalUser;
       const clusterDetails = await getClusterUuids(callCluster, timestamp, maxBucketSize);
       const [licenses, stats] = await Promise.all([
         getLicenses(clusterDetails, callCluster, maxBucketSize),
diff --git a/x-pack/plugins/monitoring/server/types.ts b/x-pack/plugins/monitoring/server/types.ts
index 3dcf6862b72325..c4a0687bef497b 100644
--- a/x-pack/plugins/monitoring/server/types.ts
+++ b/x-pack/plugins/monitoring/server/types.ts
@@ -8,9 +8,8 @@
 import { Observable } from 'rxjs';
 import type {
   IRouter,
-  ILegacyClusterClient,
   Logger,
-  ILegacyCustomClusterClient,
+  ICustomClusterClient,
   RequestHandlerContext,
   ElasticsearchClient,
 } from 'kibana/server';
@@ -71,7 +70,7 @@ export interface MonitoringCoreConfig {
 }
 
 export interface RouteDependencies {
-  cluster: ILegacyCustomClusterClient;
+  cluster: ICustomClusterClient;
   router: IRouter<RequestHandlerContextMonitoringPlugin>;
   licenseService: MonitoringLicenseService;
   encryptedSavedObjects?: EncryptedSavedObjectsPluginSetup;
@@ -87,7 +86,7 @@ export interface MonitoringCore {
 export interface LegacyShimDependencies {
   router: IRouter<RequestHandlerContextMonitoringPlugin>;
   instanceUuid: string;
-  esDataClient: ILegacyClusterClient;
+  esDataClient: ElasticsearchClient;
   kibanaStatsCollector: any;
 }