I am creating a simple grpc example using Kubernetes in an on-premises environment.

When nodejs makes a request with pythonservice, pythonservice responds with helloworld and displays it on a web page.

However, pythonservice's clusterip is accessible, but not http://pythoservice:8000.

There may be a problem with coredns, so I checked various things and deleted kube-dns service of kube-system.

And if you check with pythonservice.default.svc.cluster.local with nslookup, you will see a different address from the clusterip of pythonservice. Sorry I'm not good at English

This is the node.js code :

var setting = 'test';
var express = require('express');
var app = express();
const port = 80;
var PROTO_PATH = __dirname + '/helloworld.proto';

var grpc = require('grpc');
var protoLoader = require('@grpc/proto-loader');
var packageDefinition = protoLoader.loadSync(
    PROTO_PATH,
    {keepCase: true,
     longs: String,
     enums: String,
     defaults: true,
     oneofs: true
    });

// http://pythonservice:8000
// 10.109.228.152:8000
// pythonservice.default.svc.cluster.local:8000
// 218.38.137.28

var hello_proto = 
grpc.loadPackageDefinition(packageDefinition).helloworld;

function main(callback) {
  var client = new hello_proto.Greeter("http://pythonservice:8000", 
    grpc.credentials.createInsecure());

  var user;
  if (process.argv.length >= 3) {
    user = process.argv[2];
  } else {
    user = 'world';
  }
  client.sayHello({name: user}, function(err, response) {
    console.log('Greeting:', response.message);
    setting = response.message;
  });
}

var server = app.listen(port, function () {});

app.get('/', function (req, res) {
    main();    
    res.send(setting);
    //res.send(ip2);
    //main(function(result){
      //  res.send(result);
    //})
});

This is the yaml file for pythonservice

apiVersion: apps/v1
kind: Deployment
metadata:
  name: practice-dp2
spec:
  selector:
    matchLabels:
      app: practice-dp2
  replicas: 1 
  template:
    metadata:
      labels:
        app: practice-dp2
    spec:
      hostname: appname
      subdomain: default-subdomain
      containers:
      - name: practice-dp2
        image: taeil777/greeter-server:v1
        ports:
        - containerPort: 8000
---
apiVersion: v1
kind: Service
metadata:
  name: pythonservice
spec:
  type: ClusterIP
  selector:
    app: practice-dp2
  ports:
  - port: 8000
    targetPort: 8000

this is kubectl get all:

root@pusik-server0:/home/tinyos/Desktop/grpc/node# kubectl get all
NAME                               READY   STATUS    RESTARTS   AGE
pod/practice-dp-55dd4b9d54-v4hhq   1/1     Running   1          68m
pod/practice-dp2-7d4886876-znjtl   1/1     Running   0          18h


NAME                    TYPE        CLUSTER-IP       EXTERNAL-IP   
PORT(S)    AGE
service/kubernetes      ClusterIP   10.96.0.1        <none>        
443/TCP    34d
service/nodeservice     ClusterIP   10.100.165.53    <none>        
80/TCP     68m
service/pythonservice   ClusterIP   10.109.228.152   <none>        
8000/TCP   18h


NAME                           READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/practice-dp    1/1     1            1           68m
deployment.apps/practice-dp2   1/1     1            1           18h

NAME                                     DESIRED   CURRENT   READY   
AGE
replicaset.apps/practice-dp-55dd4b9d54   1         1         1       
68m
replicaset.apps/practice-dp2-7d4886876   1         1         1       
18h

root@pusik-server0:/home/tinyos/Desktop/grpc/python# nslookup 
pythonservice.default.svc.cluster.local
Server:     127.0.1.1
Address:    127.0.1.1#53

Name:   pythonservice.default.svc.cluster.local
Address: 218.38.137.28