基于grpc-java开发的普通工程在k8s内部署多实例，如何实现客户端流量的负载均衡

本文介绍: 本文主要讨论通过grpc-java开发的普通的java grpc工程，以多实例的方式部署在容器编排平台kubernetes（以下简称k8s）上，如何能够实现让同样部署在k8s集群内的客户端请求流量均衡的分发到多个grpc应用部署实例上去。


  package com.example.grpcserver;
  
  import io.grpc.Server;
  import io.grpc.ServerBuilder;
  import java.io.IOException;
  public class ProductInfoServer {
  Server server;
  
      public static void main(String[] args) {
          ProductInfoServer productInfoServer = new ProductInfoServer();
          productInfoServer.startServer();
          productInfoServer.blockUntilShutdown();
      }
  
      private void startServer(){
  
          int port = 50501;
          try {
              server = ServerBuilder.forPort(port).addService(new ProductInfoImpl()).build().start();
              Runtime.getRuntime().addShutdownHook(new Thread( ()-> {
                  ProductInfoServer.this.stop();
              }));
          } catch (IOException e) {
              throw new RuntimeException(e);
          }
      }
  
      private void stop(){
          if(server != null){
              server.shutdown();
          }
      }
  
      private void blockUntilShutdown(){
          if (server != null){
              try {
                  System.out.println("begin =====server.awaitTermination();");
                  server.awaitTermination();
                  System.out.println("end =====server.awaitTermination();");
              } catch (InterruptedException e) {
                  throw new RuntimeException(e);
              }
          }
  
      }
  
  }

dns

部分源码：

package com.example.grpccli;

import io.grpc.ManagedChannel;
import io.grpc.ManagedChannelBuilder;
import org.javaboy.grpc.demo.Product;
import org.javaboy.grpc.demo.ProductId;
import org.javaboy.grpc.demo.ProductInfoGrpc;

public class ProductClient {

    public static void main(String[] args) {
        // 请注意此处是要连接的service暴露的端口
        int port = 50501;
        String serverAddr = "grpc-server-headless-srv.platform";
        String dnsAddr = "dns:///"+serverAddr+":"+port;
        System.out.println("dnsAddr: " + dnsAddr);
        ManagedChannel managedChannel = ManagedChannelBuilder.forTarget("dns:///"+serverAddr+":"+port)
                .defaultLoadBalancingPolicy("round_robin").usePlaintext().build();
        ProductInfoGrpc.ProductInfoBlockingStub stub = ProductInfoGrpc.newBlockingStub(managedChannel);

        // 循环分别创建和查询100次产品
        for(int i=0; i<100; i++){
            Product product = Product.newBuilder().setId("" + i).
                    setName("TH项目-" + i).
                    setPrice(i).
                    setDescription("grpc实战项目-" + i).
                    build();

            // 添加产品
            ProductId id = stub.addProduct(product);
            System.out.println("我是增加产品: "+ id.getValue());

            // 查询产品
            Product prd = stub.getProduct(ProductId.newBuilder().setValue("" + i).build());
            System.out.println("我是查询产品:" + prd.toString());
        }


    }

}