Update grpc-tools and use package loader to read service descriptor

Author: mgilbey

package.json

@@ -30,7 +30,7 @@
     "@types/node": "^12.12.42",
     "@types/request": "2.48.0",
     "chai": "^3.5.0",
-    "grpc-tools": "^1.8.1",
+    "grpc-tools": "^1.9.0",
     "kafka-node": "2.6.1",
     "mocha": "^7.1.2",
     "npm-registry-package-info": "1.0.5",

src/dispatchers/grpc_agent.ts

@@ -15,20 +15,21 @@
  */
 
 import * as grpc from '@grpc/grpc-js';
-import { SpanAgent } from '../proto_idl_codegen/agent/spanAgent_grpc_pb';
+import * as spanAgentPackageDefinition from '../proto_idl_codegen/agent/spanAgent_grpc_pb';
 import {Dispatcher} from './dispatcher';
 import Span from '../span';
 import { Logger, NullLogger } from '../logger';
 import Utils from '../utils';
+import {ServiceClientConstructor} from '@grpc/grpc-js/build/src/make-client';
 
 export default class RemoteDispatcher implements Dispatcher {
     _client: any;
     _logger: any;
 
     constructor(agentHost: string = 'haystack-agent', agentPort: number = 35000, logger: Logger = new NullLogger()) {
         logger.info(`Initializing the remote grpc agent dispatcher, connecting at ${agentHost}:${agentPort}`);
-        const spanAgentClient = grpc.makeGenericClientConstructor(SpanAgent, 'SpanAgentService');
-        this._client = new spanAgentClient(`${agentHost}:${agentPort}`, grpc.credentials.createInsecure());
+        const protoDescriptor = grpc.loadPackageDefinition(spanAgentPackageDefinition) as {[index: string]: ServiceClientConstructor};
+        this._client = new protoDescriptor.SpanAgent(`${agentHost}:${agentPort}`, grpc.credentials.createInsecure());
         this._logger = logger;
     }