kubernetes Service Nodeport (13)

在之前的一些章节中，有hostNetwork和hostport,以及Nodeport三种服务暴露方式，nodeport跳过了service的cluster IP直接暴露出去，范围从30000-32767，不设置则动态分配，参考service第一章和hostNetwork

创建pod资源

在创建nodeport之前，先创建一个现有pod作为测试。pod的yaml文件如下：

[root@linuxea linuxea]# cat nginx.yaml 
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: nginx-linuxea
  namespace: default
spec:
  selector:
    matchLabels:
      app: nginx
      release: www
  template:
    metadata:
      labels:
        app: nginx
        release: www
    spec:
#      hostNetwork: true
      containers:
      - name: linuxea
        image: "marksugar/nginx:1.14.a"
        ports:
        - name: http
          containerPort: 80
 #         hostPort: 80

创建的pod节点

[root@linuxea linuxea]# kubectl get pods -o wide --show-labels
NAME                     READY     STATUS    RESTARTS   AGE       IP            NODE                 NOMINATED NODE   LABELS
nginx-linuxea-2qkmf      1/1       Running   0          29s       172.16.2.44   linuxea.node-2.com   <none>           app=nginx,controller-revision-hash=3080738842,pod-template-generation=1,release=www
nginx-linuxea-8hvk6      1/1       Running   0          29s       172.16.3.46   linuxea.node-3.com   <none>           app=nginx,controller-revision-hash=3080738842,pod-template-generation=1,release=www
nginx-linuxea-dk5hg      1/1       Running   0          29s       172.16.1.42   linuxea.node-1.com   <none>           app=nginx,controller-revision-hash=3080738842,pod-template-generation=1,release=www
redis-66ccc9b5df-8hmp5   1/1       Running   0          3h        172.16.1.41   linuxea.node-1.com   <none>           app=redis,pod-template-hash=2277756189,role=Logstorage

创建service nodeport

将上述的现有的pod加入到service中，标签需要和pod中的标签一样

  selector:
    app: nginx
    release: www

nodePort不指定也會被默認分配service的80端口被映射为31180端口，如下：

  - port: 80     # service 端口
    targetPort: 80  # pod中的端口
    nodePort: 31180  # node中的端口(此端口在node上唯一)，范围从30000-32767，不设置则动态分配

• 最终service yaml文件如下

apiVersion: v1
kind: Service
metadata:
  name: linuxea
  namespace: default
spec:
  selector:
    app: nginx
    release: www
  clusterIP: 10.96.66.66
  type: NodePort
  ports:
  - port: 80
    targetPort: 80
    nodePort: 31180

apply

[root@linuxea linuxea]# kubectl apply -f linuxea.yaml 
service/linuxea created
[root@linuxea linuxea]# kubectl get svc
NAME           TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)        AGE
kubernetes     ClusterIP   10.96.0.1     <none>        443/TCP        18d
linuxea        NodePort    10.96.66.66   <none>        80:31180/TCP   3s

而后在集群外部进行访问任意一个node节点ip:31180端口都可以

[root@DS-VM-Node_10_10_240_143 ~]$  while true;do curl 10.10.240.161:31180/linuxea.html; sleep 1; done
linuxea-nginx-linuxea-8hvk6.com ▍ 33b9df88388ed ▍version number 1.0
linuxea-nginx-linuxea-dk5hg.com ▍ 665b7a9dc2d42 ▍version number 1.0
linuxea-nginx-linuxea-8hvk6.com ▍ 33b9df88388ed ▍version number 1.0
linuxea-nginx-linuxea-8hvk6.com ▍ 33b9df88388ed ▍version number 1.0
linuxea-nginx-linuxea-8hvk6.com ▍ 33b9df88388ed ▍version number 1.0
linuxea-nginx-linuxea-2qkmf.com ▍ d5535d8023a09 ▍version number 1.0
linuxea-nginx-linuxea-dk5hg.com ▍ 665b7a9dc2d42 ▍version number 1.0
linuxea-nginx-linuxea-2qkmf.com ▍ d5535d8023a09 ▍version number 1.0
linuxea-nginx-linuxea-8hvk6.com ▍ 33b9df88388ed ▍version number 1.0
linuxea-nginx-linuxea-2qkmf.com ▍ d5535d8023a09 ▍version number 1.0
linuxea-nginx-linuxea-2qkmf.com ▍ d5535d8023a09 ▍version number 1.0

sessionAffinity

此刻可使用负载均衡进行调度到每台node上的31180端口，或许需要配置sessionAffinity来完成回话黏贴性，如下：其中从nodeport 31180(节点IP:PORT)转换到service port 80(其中将会内部解析调度到cluster_ip上)，在从service port 80转换到pod port 80，会经过三次转换。从nodeport转换到service port，在从service port转换到pod port可见service中的nodeport的效果便如此打补丁进行测试

[root@linuxea linuxea]# kubectl patch svc linuxea -p '{"spec":{"sessionAffinity":"ClientIP"}}'
service/linuxea patched

验证Session Affinity: ClientIP

[root@linuxea linuxea]# kubectl describe svc linuxea
Name:                     linuxea
Namespace:                default
Labels:                   <none>
Annotations:              kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"name":"linuxea","namespace":"default"},"spec":{"clusterIP":"10.96.66.66","ports":[{"n...
Selector:                 app=nginx,release=www
Type:                     NodePort
IP:                       10.96.66.66
Port:                     <unset>  80/TCP
TargetPort:               80/TCP
NodePort:                 <unset>  31180/TCP
Endpoints:                172.16.1.42:80,172.16.2.44:80,172.16.3.46:80
Session Affinity:         ClientIP
External Traffic Policy:  Cluster
Events:                   <none>

在访问时，来自同一个ip的客户端请求始终发往同一个后端pod

[root@DS-VM-Node100 ~]# while true;do curl 10.10.240.203:31180/linuxea.html; sleep 1; done
linuxea-nginx-linuxea-dk5hg.com ▍ 665b7a9dc2d42 ▍version number 1.0
linuxea-nginx-linuxea-dk5hg.com ▍ 665b7a9dc2d42 ▍version number 1.0
linuxea-nginx-linuxea-dk5hg.com ▍ 665b7a9dc2d42 ▍version number 1.0
linuxea-nginx-linuxea-dk5hg.com ▍ 665b7a9dc2d42 ▍version number 1.0
linuxea-nginx-linuxea-dk5hg.com ▍ 665b7a9dc2d42 ▍version number 1.0
linuxea-nginx-linuxea-dk5hg.com ▍ 665b7a9dc2d42 ▍version number 1.0
linuxea-nginx-linuxea-dk5hg.com ▍ 665b7a9dc2d42 ▍version number 1.0
linuxea-nginx-linuxea-dk5hg.com ▍ 665b7a9dc2d42 ▍version number 1.0
linuxea-nginx-linuxea-dk5hg.com ▍ 665b7a9dc2d42 ▍version number 1.0
linuxea-nginx-linuxea-dk5hg.com ▍ 665b7a9dc2d42 ▍version number 1.0
linuxea-nginx-linuxea-dk5hg.com ▍ 665b7a9dc2d42 ▍version number 1.0
linuxea-nginx-linuxea-dk5hg.com ▍ 665b7a9dc2d42 ▍version number 1.0