Improve dynamic config

Signed-off-by: Tianle Huang <tianleh@amazon.com>

config/opensearch_dashboards.yml

@@ -34,11 +34,11 @@
 # opensearchDashboards.configIndex: ".opensearch_dashboards_config"
 
 # Set the value of this setting to true to enable plugin application config. By default it is disabled.
-# application_config.enabled: false
+application_config.enabled: true
 
 # Set the value of this setting to true to enable plugin CSP handler. By default it is disabled.
 # It requires the application config plugin as its dependency.
-# csp_handler.enabled: false
+csp_handler.enabled: true
 
 # The default application to load.
 #opensearchDashboards.defaultAppId: "home"

src/plugins/application_config/server/opensearch_config_client.ts

@@ -3,41 +3,57 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+import LRUCache from 'lru-cache';
 import { IScopedClusterClient, Logger } from '../../../../src/core/server';
-
 import { ConfigurationClient } from './types';
 import { validate } from './string_utils';
 
 export class OpenSearchConfigurationClient implements ConfigurationClient {
   private client: IScopedClusterClient;
   private configurationIndexName: string;
   private readonly logger: Logger;
+  private cache: LRUCache<string, string>;
 
   constructor(
     scopedClusterClient: IScopedClusterClient,
     configurationIndexName: string,
-    logger: Logger
+    logger: Logger,
+    cache: LRUCache<string, string>
   ) {
     this.client = scopedClusterClient;
     this.configurationIndexName = configurationIndexName;
     this.logger = logger;
+    this.cache = cache;
   }
 
   async getEntityConfig(entity: string) {
     const entityValidated = validate(entity, this.logger);
 
+    const cachedValue = this.cache.get(entityValidated);
+
+    if (this.cache.has(entityValidated)) {
+      this.logger.info(`found value ${cachedValue} from cache`);
+      return cachedValue;
+    }
+
+    this.logger.info('No value found in cache');
+
     try {
       const data = await this.client.asInternalUser.get({
         index: this.configurationIndexName,
         id: entityValidated,
       });
+      const value = data?.body?._source?.value || '';
+
+      this.cache.set(entityValidated, value);
 
-      return data?.body?._source?.value || '';
+      return value;
     } catch (e) {
       const errorMessage = `Failed to get entity ${entityValidated} due to error ${e}`;
 
       this.logger.error(errorMessage);
 
+      this.cache.set(entityValidated, '');
       throw e;
     }
   }
@@ -55,6 +71,8 @@ export class OpenSearchConfigurationClient implements ConfigurationClient {
         },
       });
 
+      this.cache.set(entityValidated, newValueValidated);
+
       return newValueValidated;
     } catch (e) {
       const errorMessage = `Failed to update entity ${entityValidated} with newValue ${newValueValidated} due to error ${e}`;
@@ -74,6 +92,8 @@ export class OpenSearchConfigurationClient implements ConfigurationClient {
         id: entityValidated,
       });
 
+      this.cache.del(entityValidated);
+
       return entityValidated;
     } catch (e) {
       if (e?.body?.error?.type === 'index_not_found_exception') {

src/plugins/application_config/server/plugin.ts

@@ -6,6 +6,7 @@
 import { Observable } from 'rxjs';
 import { first } from 'rxjs/operators';
 
+import LRUCache from 'lru-cache';
 import {
   PluginInitializerContext,
   CoreSetup,
@@ -14,6 +15,8 @@ import {
   Logger,
   IScopedClusterClient,
   SharedGlobalConfig,
+  OpenSearchDashboardsRequest,
+  IClusterClient,
 } from '../../../core/server';
 
 import {
@@ -31,11 +34,20 @@ export class ApplicationConfigPlugin
 
   private configurationClient: ConfigurationClient;
   private configurationIndexName: string;
+  private clusterClient: IClusterClient;
+
+  private cache: LRUCache<string, string>;
 
   constructor(initializerContext: PluginInitializerContext) {
     this.logger = initializerContext.logger.get();
     this.config$ = initializerContext.config.legacy.globalConfig$;
     this.configurationIndexName = '';
+    this.clusterClient = null;
+
+    this.cache = new LRUCache({
+      max: 30,
+      maxAge: 100 * 1000,
+    });
   }
 
   private registerConfigurationClient(configurationClient: ConfigurationClient) {
@@ -50,15 +62,16 @@ export class ApplicationConfigPlugin
     this.configurationClient = configurationClient;
   }
 
-  private getConfigurationClient(scopedClusterClient: IScopedClusterClient): ConfigurationClient {
+  private getConfigurationClient(request: OpenSearchDashboardsRequest): ConfigurationClient {
     if (this.configurationClient) {
       return this.configurationClient;
     }
 
     const openSearchConfigurationClient = new OpenSearchConfigurationClient(
-      scopedClusterClient,
+      this.clusterClient.asScoped(request),
       this.configurationIndexName,
-      this.logger
+      this.logger,
+      this.cache
     );
 
     return openSearchConfigurationClient;
@@ -81,6 +94,8 @@ export class ApplicationConfigPlugin
   }
 
   public start(core: CoreStart) {
+    this.clusterClient = core.opensearch.client;
+
     return {};
   }
 

src/plugins/csp_handler/server/csp_handlers.ts

@@ -49,7 +49,7 @@ export function createCspRulesPreResponseHandler(
 
       const [coreStart] = await core.getStartServices();
 
-      const client = getConfigurationClient(coreStart.opensearch.client.asScoped(request));
+      const client = getConfigurationClient(request);
 
       const cspRules = await client.getEntityConfig(CSP_RULES_CONFIG_KEY, {
         headers: request.headers,