这种模式是生产中使用最多的，由集群内部访问时通过service域名解析得到cluster IP，客户端访问cluster IP时,系统会通过iptable或者ipvs将流量负载均衡到后端Pod上。

# svc-no-vip.yaml
apiVersion: v1
kind: Service
metadata:
  name: slb-s1
  namespace: default
spec:
  selector:
    app: nginx
    release: stable
    partition: website
    tier: slb
  ports:
  - name: http
    port: 80
    targetPort: 80

[root@maxiaoke nginx-01]# kubectl get svc
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
slb-s1       ClusterIP   10.100.138.11   <none>        80/TCP    51m
# 在node节点查看 IPVS 规则
[root@master_01_vm_160_10 ~]# ipvsadm -ln
TCP  10.100.138.11:80 rr
  -> 10.200.3.10:80               Masq    1      0          0
  -> 10.200.4.8:80                Masq    1      0          0
  -> 10.200.4.9:80                Masq    1      0          0
  -> 10.200.5.10:80               Masq    1      0          0
  -> 10.200.5.11:80               Masq    1      0          0
[root@maxiaoke yaml]# kubectl describe svc slb-s1
Name:              slb-s1
Namespace:         default
Labels:            <none>
Annotations:       <none>
Selector:          app=nginx,partition=website,release=stable,tier=slb
Type:              ClusterIP
IP Families:       <none>
IP:                10.100.138.11
IPs:               10.100.138.11
Port:              http  80/TCP
TargetPort:        80/TCP
Endpoints:         10.200.3.10:80,10.200.4.8:80,10.200.4.9:80 + 2 more...
Session Affinity:  None
Events:            <none>

# 在node节点使用VIP访问测试
[root@master_01_vm_160_10 ~]# curl 10.100.138.11/info
2021-10-13T07:24:43+00:00|v1.0.3|nginx-deploy-699fdd685d-8nb5w|ok
[root@master_01_vm_160_10 ~]# curl 10.100.138.11/info
2021-10-13T07:24:45+00:00|v1.0.3|nginx-deploy-699fdd685d-ffswz|ok
# 在pod中测试域名解析
[root@nginx-deploy-699fdd685d-4zgtx /]# curl -s http://slb-s1.default.svc.cluster.local/info  # 全域名
2021-10-13T07:28:19+00:00|v1.0.3|nginx-deploy-699fdd685d-lsv9q|ok
[root@nginx-deploy-699fdd685d-4zgtx /]# curl -s http://slb-s1/info  # 短域名
2021-10-13T07:27:57+00:00|v1.0.3|nginx-deploy-699fdd685d-ffswz|ok