register data source route handler context

Signed-off-by: Zhongnan Su <szhongna@amazon.com>

src/plugins/data_source/server/client/data_source_client.ts

@@ -0,0 +1,47 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { Logger, OpenSearchClient, SavedObjectsClientContract } from 'src/core/server';
+
+/**
+ * Represents an OpenSearch cluster API client created by the platform.
+ * It allows to call API on behalf of user defined in "data source" saved object
+ *
+ * @public
+ **/
+export interface IDataSourceClient {
+  /**
+   * Creates a {@link OpenSearchClient } bound to given data source
+   */
+  asDataSource: (dataSourceId: string) => Promise<OpenSearchClient>;
+}
+
+/**
+ * See {@link IDataSourceClient}
+ *
+ * @public
+ */
+export interface ICustomDataSourceClient extends IDataSourceClient {
+  /**
+   * Closes the data source client. After that client cannot be used and one should
+   * create a new client instance to be able to interact with OpenSearch API.
+   */
+  close: () => Promise<void>;
+}
+
+// TODO: This needs further implementation. See https://github.com/opensearch-project/OpenSearch-Dashboards/issues/1981
+export class DataSourceClient implements ICustomDataSourceClient {
+  private savedObjectClient?: SavedObjectsClientContract;
+
+  constructor(logger: Logger) {}
+  asDataSource!: (dataSourceId: string) => Promise<OpenSearchClient>;
+  // asDataSource: (dataSourceId: string) => Promise<OpenSearchClient>;
+
+  public attachSavedObjectClient(savedObjectClient: SavedObjectsClientContract) {
+    this.savedObjectClient = savedObjectClient;
+  }
+
+  public async close() {}
+}

src/plugins/data_source/server/client/index.ts

@@ -0,0 +1,6 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+export { IDataSourceClient, ICustomDataSourceClient, DataSourceClient } from './data_source_client';

src/plugins/data_source/server/data_source_route_handler_context.ts

@@ -0,0 +1,39 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+// eslint-disable-next-line max-classes-per-file
+import { Logger } from 'src/core/server';
+import { IDataSourceClient } from './client/data_source_client';
+
+class OpenSearchDataSourceRouteHandlerContext {
+  private logger: Logger;
+  constructor(private dataSourceClient: IDataSourceClient, logger: Logger) {
+    this.logger = logger;
+  }
+
+  public async getClient(dataSourceId: string) {
+    try {
+      const client = await this.dataSourceClient.asDataSource(dataSourceId);
+      return client;
+    } catch (error) {
+      // TODO: convert as audit log when integrate with osd auditing
+      this.logger.error(
+        `Fail to get data source client for dataSource id: [${dataSourceId}]. Detail: ${error.messages}`
+      );
+      throw error;
+    }
+  }
+}
+
+export class DataSourceRouteHandlerContext {
+  readonly opensearch: OpenSearchDataSourceRouteHandlerContext;
+
+  constructor(private readonly dataSourceClient: IDataSourceClient, logger: Logger) {
+    this.opensearch = new OpenSearchDataSourceRouteHandlerContext(
+      this.dataSourceClient,
+      logger.get('opensearch')
+    );
+  }
+}

src/plugins/data_source/server/plugin.ts

@@ -3,19 +3,31 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import { PluginInitializerContext, CoreSetup, CoreStart, Plugin, Logger } from 'src/core/server';
+import {
+  PluginInitializerContext,
+  CoreSetup,
+  CoreStart,
+  Plugin,
+  Logger,
+  IContextProvider,
+  RequestHandler,
+} from '../../../../src/core/server';
+import { DataSourceClient } from './client/data_source_client';
+import { DataSourceRouteHandlerContext } from './data_source_route_handler_context';
 import { dataSource, credential } from './saved_objects';
 
 import { DataSourcePluginSetup, DataSourcePluginStart } from './types';
 
 export class DataSourcePlugin implements Plugin<DataSourcePluginSetup, DataSourcePluginStart> {
   private readonly logger: Logger;
+  private readonly dataSourceClient: DataSourceClient;
 
   constructor(initializerContext: PluginInitializerContext) {
     this.logger = initializerContext.logger.get();
+    this.dataSourceClient = new DataSourceClient(this.logger);
   }
 
-  public setup(core: CoreSetup) {
+  public async setup(core: CoreSetup) {
     this.logger.debug('data_source: Setup');
 
     // Register credential saved object type
@@ -24,6 +36,9 @@ export class DataSourcePlugin implements Plugin<DataSourcePluginSetup, DataSourc
     // Register data source saved object type
     core.savedObjects.registerType(dataSource);
 
+    // Register plugin context to route handler context
+    core.http.registerRouteHandlerContext('data_source', this.createRouteHandlerContext(core));
+
     return {};
   }
 
@@ -32,5 +47,17 @@ export class DataSourcePlugin implements Plugin<DataSourcePluginSetup, DataSourc
     return {};
   }
 
-  public stop() {}
+  public stop() {
+    this.dataSourceClient.close();
+  }
+
+  private createRouteHandlerContext = (
+    core: CoreSetup
+  ): IContextProvider<RequestHandler<unknown, unknown, unknown>, 'data_source'> => {
+    return async (context, req) => {
+      const [{ savedObjects }] = await core.getStartServices();
+      this.dataSourceClient.attachSavedObjectClient(savedObjects.getScopedClient(req));
+      return new DataSourceRouteHandlerContext(this.dataSourceClient, this.logger);
+    };
+  };
 }

src/plugins/data_source/server/types.ts

@@ -3,6 +3,19 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+import { OpenSearchClient } from 'src/core/server';
+
+export interface DataSourcePluginRequestContext {
+  opensearch: {
+    getClient: (dataSourceId: string) => Promise<OpenSearchClient>;
+  };
+}
+declare module 'src/core/server' {
+  interface RequestHandlerContext {
+    data_source: DataSourcePluginRequestContext;
+  }
+}
+
 // eslint-disable-next-line @typescript-eslint/no-empty-interface
 export interface DataSourcePluginSetup {}
 // eslint-disable-next-line @typescript-eslint/no-empty-interface