docker - 通过kubectl公开服务时，从节点主机上没有监听端口

Question

我正在设置一个kubernetes集群，其中有一个主节点(一台物理miniPC，运行ubuntu服务器18.04)和一个从属节点(一台笔记本电脑，运行ubuntu 16.04)。

Docker是我与kubernetes结合使用的容器。

我通过运行一个演示应用程序

kubectl run hello-world --image=gcr.io/google-samples/hello-app:1.0  --port 8080

并通过公开

kubectl expose deployment hello-world --port=8080 --target-port=8080

该应用程序在从节点上启动

alecu@slave-node:~$ sudo docker ps
CONTAINER ID        IMAGE                  COMMAND                  CREATED             STATUS              PORTS               NAMES
91967f160a7c        bc5c421ecd6c           "./hello-app"            About an hour ago   Up About an hour                        k8s_hello-world_hello-world-5bcc568dd9-xktwg_default_875609f4-90d0-11e9-9940-7cd30a0da72f_0

我可以从容器内部访问它

alecu@slave-node:~$ sudo nsenter -t 21075 -n curl http://localhost:8080
Hello, world!
Version: 1.0.0
Hostname: hello-world-6899bf7846-t5pb7

但是，当我尝试从容器外部访问它时，连接被拒绝:

alecu@slave-node:~$ curl http://localhost:8080
curl: (7) Failed to connect to localhost port 8080: Connection refused

netstat不显示8080端口

alecu@slave-node:~$ netstat -tnlp | grep 8080

curl也无法在主节点上运行

alecu@master-node:~$ kubectl describe service hello-world
Name:              hello-world
Namespace:         default
Labels:            <none>
Annotations:       <none>
Selector:          run=hello-world
Type:              ClusterIP
IP:                10.100.48.99
Port:              <unset>  8080/TCP
TargetPort:        8080/TCP
Endpoints:         192.168.1.18:8080
Session Affinity:  None
Events:            <none>

alecu@master-node:~$ curl -v http://192.168.1.18:8080
* Rebuilt URL to: http://192.168.1.18:8080/
*   Trying 192.168.1.18...
* TCP_NODELAY set
^C
alecu@master-node:~$ curl -v http://10.100.48.99:8080
* Rebuilt URL to: http://10.100.48.99:8080/
*   Trying 10.100.48.99...
* TCP_NODELAY set
^C
alecu@master-node:~$

我'ctrl + c' curl 命令，因为它无休止的等待。

我不明白为什么从节点8080端口未打开。

[编辑]
我修补了服务以使用NodePort

 kubectl patch svc hello-world --type='json' -p '[{"op":"replace","path":"/spec/type","value":"NodePort"}]'

但在 http://nodeIP:nodePort上 curl 也不起作用

alecu@master-node:~$ kubectl describe svc hello-world
Name:                     hello-world
Namespace:                default
Labels:                   run=hello-world
Annotations:              <none>
Selector:                 run=hello-world
Type:                     NodePort
IP:                       10.100.171.36
Port:                     <unset>  8080/TCP
TargetPort:               8080/TCP
NodePort:                 <unset>  30988/TCP
Endpoints:                192.168.1.21:8080
Session Affinity:         None
External Traffic Policy:  Cluster
Events:                   <none>
alecu@master-node:~$ curl -v http://10.100.171.36:30988
* Rebuilt URL to: http://10.100.171.36:30988/
*   Trying 10.100.171.36...
* TCP_NODELAY set
^C

Answer 1

将服务类型更新为NodePort。那么您应该可以使用http://NODEIP:NODEPORT从外部访问该应用程序
或使用clusterIP从群集访问应用程序。

从以下命令获取clusterIP

kubectl get svc

请参阅以下说明

master $ kubectl run hello-world --image=gcr.io/google-samples/hello-app:1.0  --port 8080
deployment.apps/hello-world created
master $
master $ kubectl expose deployment hello-world --port=8080 --target-port=8080
service/hello-world exposed
master $
master $ kubectl get svc
NAME          TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)         AGE
hello-world   ClusterIP   10.104.172.60   <none>        8080/TCP        4s
kube-dns      ClusterIP   10.96.0.10      <none>        53/UDP,53/TCP   1h
master $
master $ curl 10.104.172.60:8080
Hello, world!
Version: 1.0.0
Hostname: hello-world-6654767c49-r2mnz