diff --git a/x-pack/plugins/watcher/server/plugin.ts b/x-pack/plugins/watcher/server/plugin.ts
index 88cecf5335..75f727b738 100644
--- a/x-pack/plugins/watcher/server/plugin.ts
+++ b/x-pack/plugins/watcher/server/plugin.ts
@@ -17,6 +17,7 @@ import {
   Plugin,
   PluginInitializerContext,
 } from 'kibana/server';
+import { once } from 'lodash';
 import { PLUGIN } from '../common/constants';
 import { Dependencies, LicenseStatus, RouteDependencies } from './types';
 import { LICENSE_CHECK_STATE } from '../../licensing/server';
@@ -31,7 +32,7 @@ import { registerLoadHistoryRoute } from './routes/api/register_load_history_rou
 import { elasticsearchJsPlugin } from './lib/elasticsearch_js_plugin';
 
 export interface WatcherContext {
-  client: IScopedClusterClient;
+  getClient: () => Promise<IScopedClusterClient>;
 }
 
 export class WatcherServerPlugin implements Plugin<void, void, any, any> {
@@ -52,19 +53,15 @@ export class WatcherServerPlugin implements Plugin<void, void, any, any> {
       getLicenseStatus: () => this.licenseStatus,
     };
 
-    const getWatcherEsClient = async () => {
+    const getWatcherEsClient = once(async () => {
       const [coreStart] = await getStartServices();
       const config = { plugins: [elasticsearchJsPlugin] };
       return coreStart.elasticsearch.legacy.createClient('watcher', config);
-    };
+    });
+
     http.registerRouteHandlerContext('watcher', (ctx, request) => {
       return {
-        client: {
-          callAsCurrentUser: async (...args) =>
-            (await getWatcherEsClient()).asScoped(request).callAsCurrentUser(...args),
-          callAsInternalUser: async (...args) =>
-            (await getWatcherEsClient()).asScoped(request).callAsInternalUser(...args),
-        },
+        getClient: async () => (await getWatcherEsClient()).asScoped(request),
       };
     });
 
diff --git a/x-pack/plugins/watcher/server/routes/api/register_list_fields_route.ts b/x-pack/plugins/watcher/server/routes/api/register_list_fields_route.ts
index d72e5ad2f8..89a9daf56a 100644
--- a/x-pack/plugins/watcher/server/routes/api/register_list_fields_route.ts
+++ b/x-pack/plugins/watcher/server/routes/api/register_list_fields_route.ts
@@ -40,7 +40,7 @@ export function registerListFieldsRoute(deps: RouteDependencies) {
       const { indexes } = request.body;
 
       try {
-        const fieldsResponse = await fetchFields(ctx.watcher!.client, indexes);
+        const fieldsResponse = await fetchFields(await ctx.watcher!.getClient(), indexes);
         const json = fieldsResponse.status === 404 ? { fields: [] } : fieldsResponse;
         const fields = Fields.fromUpstreamJson(json);
         return response.ok({ body: fields.downstreamJson });

diff --git a/src/core/server/elasticsearch/elasticsearch_service.ts b/src/core/server/elasticsearch/elasticsearch_service.ts
index 9785bd6700..135767d931 100644
--- a/src/core/server/elasticsearch/elasticsearch_service.ts
+++ b/src/core/server/elasticsearch/elasticsearch_service.ts
@@ -70,6 +70,7 @@ export class ElasticsearchService
     clientConfig?: Partial<ElasticsearchClientConfig>
   ) => ICustomClusterClient;
   private adminClient?: IClusterClient;
+  private customClients?: WeakMap<object, ICustomClusterClient>;
 
   constructor(private readonly coreContext: CoreContext) {
     this.kibanaVersion = coreContext.env.packageInfo.version;
@@ -182,9 +183,15 @@ export class ElasticsearchService
       kibanaVersion: this.kibanaVersion,
     }).pipe(takeUntil(this.stop$), shareReplay({ refCount: true, bufferSize: 1 }));
 
+    this.customClients = new WeakMap();
     this.createClient = (type: string, clientConfig: Partial<ElasticsearchClientConfig> = {}) => {
+      if (this.customClients!.has({ type, clientConfig })) {
+        return this.customClients!.get({ type, clientConfig })!;
+      }
       const finalConfig = merge({}, config, clientConfig);
-      return this.createClusterClient(type, finalConfig, deps.http.getAuthHeaders);
+      const customClient = this.createClusterClient(type, finalConfig, deps.http.getAuthHeaders);
+      this.customClients!.set({ type, clientConfig }, customClient);
+      return customClient;
     };
 
     return {
diff --git a/src/core/server/index.ts b/src/core/server/index.ts
index 4a1ac8988e..92755d9d48 100644
--- a/src/core/server/index.ts
+++ b/src/core/server/index.ts
@@ -322,6 +322,12 @@ export interface RequestHandlerContext {
     elasticsearch: {
       dataClient: IScopedClusterClient;
       adminClient: IScopedClusterClient;
+      legacy: {
+        createScopedClient: (
+          type: string,
+          clientConfig?: Partial<ElasticsearchClientConfig>
+        ) => IScopedClusterClient;
+      };
     };
     uiSettings: {
       client: IUiSettingsClient;
diff --git a/src/core/server/server.ts b/src/core/server/server.ts
index 86f1b5153d..25b82ce64e 100644
--- a/src/core/server/server.ts
+++ b/src/core/server/server.ts
@@ -244,8 +244,15 @@ export class Server {
             typeRegistry: this.coreStart!.savedObjects.getTypeRegistry(),
           },
           elasticsearch: {
-            adminClient: coreSetup.elasticsearch.adminClient.asScoped(req),
-            dataClient: coreSetup.elasticsearch.dataClient.asScoped(req),
+            adminClient: this.coreStart!.elasticsearch.legacy.client.asScoped(req),
+            dataClient: this.coreStart!.elasticsearch.legacy.client.asScoped(req),
+            legacy: {
+              createScopedClient: (
+                type: string,
+                clientConfig: Partial<ElasticsearchClientConfig>
+              ) =>
+                this.coreStart!.elasticsearch.legacy.createClient(type, clientConfig).asScoped(req),
+            },
           },
           uiSettings: {
             client: uiSettingsClient,
diff --git a/x-pack/plugins/watcher/server/plugin.ts b/x-pack/plugins/watcher/server/plugin.ts
index dcbc7e6526..a807866115 100644
--- a/x-pack/plugins/watcher/server/plugin.ts
+++ b/x-pack/plugins/watcher/server/plugin.ts
@@ -10,7 +10,6 @@ declare module 'kibana/server' {
   }
 }
 
-import { once } from 'lodash';
 import {
   CoreSetup,
   IScopedClusterClient,
@@ -53,21 +52,11 @@ export class WatcherServerPlugin implements Plugin<void, void, any, any> {
       getLicenseStatus: () => this.licenseStatus,
     };
 
-    const getWatcherEsClient = once(async () => {
-      const [coreStart] = await getStartServices();
-      const config = { plugins: [elasticsearchJsPlugin] };
-      return coreStart.elasticsearch.legacy.createClient('watcher', config);
-    });
-    http.registerRouteHandlerContext('watcher', (ctx, request) => {
-      return {
-        client: {
-          callAsCurrentUser: async (...args) =>
-            (await getWatcherEsClient()).asScoped(request).callAsCurrentUser(...args),
-          callAsInternalUser: async (...args) =>
-            (await getWatcherEsClient()).asScoped(request).callAsInternalUser(...args),
-        },
-      };
-    });
+    const config = { plugins: [elasticsearchJsPlugin] };
+
+    http.registerRouteHandlerContext('watcher', (ctx, request) => ({
+      client: ctx.core.elasticsearch.legacy.createScopedClient('watcher', config),
+    }));
 
     registerListFieldsRoute(routeDependencies);
     registerLoadHistoryRoute(routeDependencies);