我在从DigitalOcean租用的两台服务器上使用kubeadm启动了kubernetes集群。我使用Flannel作为CNI。启动集群后，我按照this教程创建了部署和服务。
$ kubectl describe svc example-service
Name: example-service
Namespace: default
Labels: <none>
Annotations: <none>
Selector: run=load-balancer-example
Type: NodePort
IP: 10.99.217.181
Port: <unset> 8080/TCP
TargetPort: 8080/TCP
NodePort: <unset> 31570/TCP
Endpoints: 10.244.1.2:8080,10.244.1.3:8080
Session Affinity: None
External Traffic Policy: Cluster
Events: <none>
尝试从主节点（server1）访问pod
$ curl 10.244.1.2:8080
curl: (7) Failed to connect to 10.244.1.2 port 8080: Connection timed out
$ curl 10.244.1.3:8080
curl: (7) Failed to connect to 10.244.1.3 port 8080: Connection timed out
$ curl curl 10.99.217.181:8080
curl: (7) Failed to connect to 10.99.217.181 port 8080: Connection timed out
$ curl [server1-ip]:31570
curl: (7) Failed to connect to [server1-ip] port 31570: Connection timed out
$ curl [server2-ip]:31570
curl: (7) Failed to connect to [server2-ip] port 31570: Connection timed out
尝试从辅助节点（server2）访问pod
$ curl 10.244.1.2:8080
Hello Kubernetes!
$ curl 10.244.1.3:8080
Hello Kubernetes!
$ curl curl 10.99.217.181:8080
Hello Kubernetes!
$ curl [server1-ip]:31570
curl: (7) Failed to connect to [server1-ip] port 31570: Connection timed out
$ curl [server2-ip]:31570
Hello Kubernetes!