[APM] Add index.fast_refresh to .apm-custom-link (#159674)

Closes: #155330

Adds `index.fast_refresh` to `.apm-custom-link` in order to ensure fast
index refreshes on serverless (1 second periodic refreshes instead of 5
second which is the new default on serverless).

This is pending on Elasticsearch adding support for `index.fast_refresh`
(elastic/elasticsearch#96660)

---------

Co-authored-by: miriam.aparicio <miriam.aparicio@gmail.com>
Co-authored-by: Miriam <31922082+MiriamAparicio@users.noreply.github.com>

config/serverless.oblt.yml

@@ -35,6 +35,7 @@ xpack.apm.featureFlags.infraUiAvailable: false
 xpack.apm.featureFlags.migrationToFleetAvailable: false
 xpack.apm.featureFlags.sourcemapApiAvailable: false
 xpack.apm.featureFlags.storageExplorerAvailable: false
+xpack.apm.featureFlags.fastRefreshAvailable: true
 
 # Specify in telemetry the project type
 telemetry.labels.serverless: observability

test/plugin_functional/test_suites/core_plugins/rendering.ts

@@ -186,6 +186,7 @@ export default function ({ getService }: PluginFunctionalProviderContext) {
         'xpack.apm.latestAgentVersionsUrl (string)',
         'xpack.apm.featureFlags.agentConfigurationAvailable (any)',
         'xpack.apm.featureFlags.configurableIndicesAvailable (any)',
+        'xpack.apm.featureFlags.fastRefreshAvailable (any)',
         'xpack.apm.featureFlags.infrastructureTabAvailable (any)',
         'xpack.apm.featureFlags.infraUiAvailable (any)',
         'xpack.apm.featureFlags.migrationToFleetAvailable (any)',

x-pack/plugins/apm/common/apm_feature_flags.ts

@@ -16,6 +16,7 @@ export enum ApmFeatureFlagName {
   MigrationToFleetAvailable = 'migrationToFleetAvailable',
   SourcemapApiAvailable = 'sourcemapApiAvailable',
   StorageExplorerAvailable = 'storageExplorerAvailable',
+  FastRefreshAvailable = 'fastRefreshAvailable',
 }
 
 const apmFeatureFlagMap = {
@@ -47,6 +48,10 @@ const apmFeatureFlagMap = {
     default: true,
     type: t.boolean,
   },
+  [ApmFeatureFlagName.FastRefreshAvailable]: {
+    default: false,
+    type: t.boolean,
+  },
 };
 
 type ApmFeatureFlagMap = typeof apmFeatureFlagMap;

x-pack/plugins/apm/public/context/apm_plugin/mock_apm_plugin_context.tsx

@@ -79,6 +79,7 @@ const mockConfig: ConfigSchema = {
     migrationToFleetAvailable: true,
     sourcemapApiAvailable: true,
     storageExplorerAvailable: true,
+    fastRefreshAvailable: false,
   },
   serverless: { enabled: false },
 };

x-pack/plugins/apm/public/index.ts

@@ -24,6 +24,7 @@ export interface ConfigSchema {
     migrationToFleetAvailable: boolean;
     sourcemapApiAvailable: boolean;
     storageExplorerAvailable: boolean;
+    fastRefreshAvailable: boolean;
   };
   serverless: {
     enabled: boolean;

x-pack/plugins/apm/server/index.ts

@@ -23,6 +23,15 @@ const disabledOnServerless = schema.conditional(
   schema.oneOf([schema.literal(true)], { defaultValue: true })
 );
 
+const enabledOnServerless = schema.conditional(
+  schema.contextRef('serverless'),
+  true,
+  schema.boolean({
+    defaultValue: true,
+  }),
+  schema.oneOf([schema.literal(false)], { defaultValue: false })
+);
+
 // All options should be documented in the APM configuration settings: https://github.com/elastic/kibana/blob/main/docs/settings/apm-settings.asciidoc
 // and be included on cloud allow list unless there are specific reasons not to
 const configSchema = schema.object({
@@ -88,6 +97,7 @@ const configSchema = schema.object({
     migrationToFleetAvailable: disabledOnServerless,
     sourcemapApiAvailable: disabledOnServerless,
     storageExplorerAvailable: disabledOnServerless,
+    fastRefreshAvailable: enabledOnServerless,
   }),
   serverless: schema.object({
     enabled: schema.conditional(

x-pack/plugins/apm/server/plugin.ts

@@ -277,6 +277,7 @@ export class APMPlugin
 
     const logger = this.logger;
     const client = core.elasticsearch.client.asInternalUser;
+    const { featureFlags } = this.currentConfig;
 
     // create .apm-agent-configuration index without blocking start lifecycle
     createApmAgentConfigurationIndex({ client, logger }).catch((e) => {
@@ -285,7 +286,7 @@ export class APMPlugin
     });
 
     // create .apm-custom-link index without blocking start lifecycle
-    createApmCustomLinkIndex({ client, logger }).catch((e) => {
+    createApmCustomLinkIndex({ client, logger, featureFlags }).catch((e) => {
       logger.error('Failed to create .apm-custom-link index');
       logger.error(e);
     });

x-pack/plugins/apm/server/routes/settings/custom_link/create_custom_link_index.ts

@@ -12,19 +12,29 @@ import {
   Mappings,
 } from '@kbn/observability-plugin/server';
 import { APM_CUSTOM_LINK_INDEX } from '../apm_indices/get_apm_indices';
+import { ApmFeatureFlags } from '../../../../common/apm_feature_flags';
 
 export const createApmCustomLinkIndex = async ({
   client,
   logger,
+  featureFlags,
 }: {
   client: ElasticsearchClient;
   logger: Logger;
+  featureFlags: ApmFeatureFlags;
 }) => {
   return createOrUpdateIndex({
     index: APM_CUSTOM_LINK_INDEX,
     client,
     logger,
     mappings,
+    settings: featureFlags.fastRefreshAvailable
+      ? {
+          index: {
+            fast_refresh: true,
+          },
+        }
+      : {},
   });
 };
 

x-pack/plugins/observability/server/lib/annotations/create_annotations_client.ts

@@ -34,9 +34,9 @@ export function createAnnotationsClient(params: {
   const initIndex = () =>
     createOrUpdateIndex({
       index,
-      mappings,
       client: esClient,
       logger,
+      mappings,
     });
 
   function ensureGoldLicense<T extends (...args: any[]) => any>(fn: T): T {

x-pack/plugins/observability/server/utils/create_or_update_index.ts

@@ -7,18 +7,23 @@
 import type * as estypes from '@elastic/elasticsearch/lib/api/typesWithBodyKey';
 import pRetry from 'p-retry';
 import { Logger, ElasticsearchClient } from '@kbn/core/server';
+import { merge } from 'lodash';
 
 export type Mappings = Required<estypes.IndicesCreateRequest>['body']['mappings'] &
   Required<estypes.IndicesPutMappingRequest>['body'];
 
+type IndexSettings = Required<estypes.IndicesPutSettingsRequest>['body']['settings'];
+
 export async function createOrUpdateIndex({
   index,
   mappings,
+  settings,
   client,
   logger,
 }: {
   index: string;
   mappings: Mappings;
+  settings?: IndexSettings;
   client: ElasticsearchClient;
   logger: Logger;
 }) {
@@ -44,6 +49,7 @@ export async function createOrUpdateIndex({
               index,
               client,
               mappings,
+              settings,
             });
 
         if (!result.acknowledged) {
@@ -64,26 +70,28 @@ export async function createOrUpdateIndex({
   }
 }
 
-function createNewIndex({
+async function createNewIndex({
   index,
   client,
   mappings,
+  settings,
 }: {
   index: string;
   client: ElasticsearchClient;
   mappings: Required<estypes.IndicesCreateRequest>['body']['mappings'];
+  settings: Required<estypes.IndicesPutSettingsRequest>['body']['settings'];
 }) {
-  return client.indices.create({
+  return await client.indices.create({
     index,
     body: {
       // auto_expand_replicas: Allows cluster to not have replicas for this index
-      settings: { index: { auto_expand_replicas: '0-1' } },
+      settings: merge({ index: { auto_expand_replicas: '0-1' } }, settings),
       mappings,
     },
   });
 }
 
-function updateExistingIndex({
+async function updateExistingIndex({
   index,
   client,
   mappings,
@@ -92,7 +100,7 @@ function updateExistingIndex({
   client: ElasticsearchClient;
   mappings: estypes.IndicesPutMappingRequest['body'];
 }) {
-  return client.indices.putMapping({
+  return await client.indices.putMapping({
     index,
     body: mappings,
   });