kubernetes - K8s NodePort 服务为 “unreachable by IP” 仅在集群中的 2/4 从站上

Question

我使用 kubeadm 创建了一个包含 5 个虚拟机的 K8s 集群(运行 Ubuntu 16.04.3 LTS 的 1 个主机和 4 个从机) .我用过 flannel在集群中设置网络。我能够成功部署一个应用程序。然后，我通过 NodePort 服务公开了它。从这里开始，事情对我来说变得复杂了。

在开始之前，我禁用了默认 firewalld主节点和节点上的服务。

据我了解 K8s Services doc ，NodePort 类型在集群中的所有节点上公开服务。但是，当我创建它时，该服务仅在集群中的 4 个节点中的 2 个节点上公开。我猜这不是预期的行为(对吗？)

对于故障排除，以下是一些资源规范:

root@vm-vivekse-003:~# kubectl get nodes
NAME              STATUS    AGE       VERSION
vm-deepejai-00b   Ready     5m        v1.7.3
vm-plashkar-006   Ready     4d        v1.7.3
vm-rosnthom-00f   Ready     4d        v1.7.3
vm-vivekse-003    Ready     4d        v1.7.3   //the master
vm-vivekse-004    Ready     16h       v1.7.3

root@vm-vivekse-003:~# kubectl get pods -o wide -n playground
NAME                                     READY     STATUS    RESTARTS   AGE       IP           NODE
kubernetes-bootcamp-2457653786-9qk80     1/1       Running   0          2d        10.244.3.6   vm-rosnthom-00f
springboot-helloworld-2842952983-rw0gc   1/1       Running   0          1d        10.244.3.7   vm-rosnthom-00f

root@vm-vivekse-003:~# kubectl get svc -o wide -n playground
NAME        CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE       SELECTOR
sb-hw-svc   10.101.180.19   <nodes>       9000:30847/TCP   5h        run=springboot-helloworld

root@vm-vivekse-003:~# kubectl describe svc sb-hw-svc -n playground
Name:               sb-hw-svc
Namespace:          playground
Labels:             <none>
Annotations:        <none>
Selector:           run=springboot-helloworld
Type:               NodePort
IP:                 10.101.180.19
Port:               <unset>   9000/TCP
NodePort:           <unset>   30847/TCP
Endpoints:          10.244.3.7:9000
Session Affinity:   None
Events:             <none>

root@vm-vivekse-003:~# kubectl get endpoints sb-hw-svc -n playground -o yaml
apiVersion: v1
kind: Endpoints
metadata:
  creationTimestamp: 2017-08-09T06:28:06Z
  name: sb-hw-svc
  namespace: playground
  resourceVersion: "588958"
  selfLink: /api/v1/namespaces/playground/endpoints/sb-hw-svc
  uid: e76d9cc1-7ccb-11e7-bc6a-fa163efaba6b
subsets:
- addresses:
  - ip: 10.244.3.7
    nodeName: vm-rosnthom-00f
    targetRef:
      kind: Pod
      name: springboot-helloworld-2842952983-rw0gc
      namespace: playground
      resourceVersion: "473859"
      uid: 16d9db68-7c1a-11e7-bc6a-fa163efaba6b
  ports:
  - port: 9000
    protocol: TCP

经过一番修补后，我意识到在这 2 个“故障”节点上，这些服务在这些主机本身中不可用。

Node01(工作):

root@vm-vivekse-004:~# curl 127.0.0.1:30847      //<localhost>:<nodeport>
Hello Docker World!!
root@vm-vivekse-004:~# curl 10.101.180.19:9000   //<cluster-ip>:<port>
Hello Docker World!!
root@vm-vivekse-004:~# curl 10.244.3.7:9000      //<pod-ip>:<port>
Hello Docker World!!

Node02(工作):

root@vm-rosnthom-00f:~# curl 127.0.0.1:30847
Hello Docker World!!
root@vm-rosnthom-00f:~# curl 10.101.180.19:9000
Hello Docker World!!
root@vm-rosnthom-00f:~# curl 10.244.3.7:9000
Hello Docker World!!

Node03(不工作):

root@vm-plashkar-006:~# curl 127.0.0.1:30847
curl: (7) Failed to connect to 127.0.0.1 port 30847: Connection timed out
root@vm-plashkar-006:~# curl 10.101.180.19:9000
curl: (7) Failed to connect to 10.101.180.19 port 9000: Connection timed out
root@vm-plashkar-006:~# curl 10.244.3.7:9000
curl: (7) Failed to connect to 10.244.3.7 port 9000: Connection timed out

Node04(不工作):

root@vm-deepejai-00b:/# curl 127.0.0.1:30847
curl: (7) Failed to connect to 127.0.0.1 port 30847: Connection timed out
root@vm-deepejai-00b:/# curl 10.101.180.19:9000
curl: (7) Failed to connect to 10.101.180.19 port 9000: Connection timed out
root@vm-deepejai-00b:/# curl 10.244.3.7:9000
curl: (7) Failed to connect to 10.244.3.7 port 9000: Connection timed out

试过 netstat和 telnet在所有 4 个奴隶上。这是输出:

Node01(工作主机):

root@vm-vivekse-004:~# netstat -tulpn | grep 30847
tcp6       0      0 :::30847                :::*                    LISTEN      27808/kube-proxy
root@vm-vivekse-004:~# telnet 127.0.0.1 30847
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.

Node02(工作主机):

root@vm-rosnthom-00f:~# netstat -tulpn | grep 30847
tcp6       0      0 :::30847                :::*                    LISTEN      11842/kube-proxy
root@vm-rosnthom-00f:~# telnet 127.0.0.1 30847
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.

Node03(不工作的主机):

root@vm-plashkar-006:~# netstat -tulpn | grep 30847
tcp6       0      0 :::30847                :::*                    LISTEN      7791/kube-proxy
root@vm-plashkar-006:~# telnet 127.0.0.1 30847
Trying 127.0.0.1...
telnet: Unable to connect to remote host: Connection timed out

Node04(不工作的主机):

root@vm-deepejai-00b:/# netstat -tulpn | grep 30847
tcp6       0      0 :::30847                :::*                    LISTEN      689/kube-proxy
root@vm-deepejai-00b:/# telnet 127.0.0.1 30847
Trying 127.0.0.1...
telnet: Unable to connect to remote host: Connection timed out

补充资料:

来自 kubectl get pods输出，可以看到pod实际上部署在slave上 vm-rosnthom-00f .我可以 ping该主机来自所有 5 个虚拟机和 curl vm-rosnthom-00f:30847也适用于所有 VM。

我可以清楚地看到内部集群网络困惑，但我不知道如何解决! iptables -L因为所有从站都是相同的，甚至所有从站的本地环回( ifconfig lo )都已启动并运行。我完全不知道如何修复它!

Answer 1

如果你想从集群中的任何节点访问服务，你需要精细的服务类型为 ClusterIP .由于您将服务类型定义为 NodePort ，您可以从运行服务的节点进行连接。

我上面的答案不正确，根据文档，我们应该能够从任何 NodeIP:Nodeport 连接.但它也不适用于我的集群。

https://kubernetes.io/docs/concepts/services-networking/service/#publishing-services---service-types

NodePort: Exposes the service on each Node’s IP at a static port (the NodePort). A ClusterIP service, to which the NodePort service will route, is automatically created. You’ll be able to contact the NodePort service, from outside the cluster, by requesting :.

我的节点 ip forward 之一未设置。我能够使用 NodeIP:nodePort 连接我的服务

sysctl -w net.ipv4.ip_forward=1