Service

                                        #创建一个web
[root@master ~]# kubectl create deployment nginx --image=nginx
deployment.apps/nginx created
[root@master ~]#                        #把web应用暴露出去
[root@master ~]#  kubectl expose deployment nginx --port=80 --type=NodePort
service/nginx exposed
[root@master ~]#                        #外部客户通过server来访问web的应用，这就是service存在的意义
[root@master ~]#  kubectl get pod,svc
NAME                        READY   STATUS              RESTARTS   AGE
pod/nginx-f89759699-52lfr   0/1     ContainerCreating   0          36s

NAME                 TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)        AGE
service/nginx        NodePort    10.102.12.94   <none>        80:30002/TCP   8s
[root@master ~]# 

[root@master ~]# cat java-demo2.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
    name: java-demo2
spec:
    replicas: 2             #当deployment中有多个容器时，外部客户端要访问deployment的应用
    selector:               #就需要通过service,这时的service就相当于一个loadblance
        matchLabels:
            app: java-demo
            project: blog
    template:
        metadata:
            labels:
                app: java-demo
                project: blog
        spec:
            containers:
            - image: lizhenliang/java-demo
                imagePullPolicy: Always
                name: web
                ports:
                - containerPort: 80
[root@master ~]# 

[root@master ~]# cat deployment4.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
    name: java-demo2                    #deployment的名称是java-demo2
spec:
    replicas: 3
    selector: 
        matchLabels:
            project: blog
            app: java-demo              #deployment中的project/app的值要与pod中一样
    template:                           #否则无法匹配到该Pod
        metadata:
            labels:
                project: blog
                app: java-demo
        spec:
            containers:
            - name: web
                image: lizhenliang/java-demo
                ports:
                - containerPort: 80
[root@master ~]# 

[root@master ~]# cat service4.yaml 
apiVersion: v1                         #service的版本
kind: Service                          #资源的类型
metadata:
    name: java-demo2                   #一般与deploy名称一样
spec:
    selector:                          #通过标签选择器来匹配deploy中的pod，名为java-demo2的service对应
        project: blog                                   #的pod就是名为java-demo2中的depmloyemnt中的三个pod,这三个pod的
        app: java-demo                                 #地址为 10.244.1.156:8080，10.244.2.234:8080,10.244.2.235:8080    
    ports:                                                       
        - protocol: TCP
            port: 80
            targetPort: 8080
    type: NodePort
[root@master ~]# 

[root@master ~]# kubectl get svc  java-demo2
NAME         TYPE       CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
java-demo2   NodePort   10.104.171.129   <none>        80:30997/TCP   34s
[root@master ~]#                                     
[root@master ~]#                                          #查看java-demo2这个service关联的后端应用，后面的地址分别为
[root@master ~]#                                          #10.244.1.156:8080,10.244.2.234:8080,10.244.2.235:8080
[root@master ~]#                                          #service与endpoints是一一对应的，service创建时endpoints会自动生成
[root@master ~]# kubectl  get endpoints   java-demo2
NAME         ENDPOINTS                                               AGE
java-demo2   10.244.1.156:8080,10.244.2.234:8080,10.244.2.235:8080   3m7s
[root@master ~]# 

手工手成一个service文件
                                         #生成service之前需要有一个deploy的资源
                                         #为名为java-demo2的deploy暴露服务  --port=80 cluserIP的端口为80
                                           # --target-port=80 Pod内的端口为80，在为deploy暴露服务的同时导出yaml文件
[root@master ~]# kubectl apply -f java-demo2.yaml 
deployment.apps/java-demo2 created
[root@master ~]# kubectl expose deploy java-demo2 --port=80 --target-port=80 --dry-run=client -o yaml > service5.yaml
[root@master ~]# vim service5.yaml     #编辑yaml文件，删除系统的状态信息
apiVersion: v1
kind: Service
metadata:
    name: java-demo2
spec:
    ports:
    - port: 80
        protocol: TCP
        targetPort: 80
    selector:
        app: java-demo
        project: blog
[root@master ~]#
清空pod为后续实验提供简洁的环境
[root@master ~]# kubectl  delete deploy java-demo2
deployment.apps "java-demo2" deleted  #生成一个deploy文件,并使用deployment部署pod
[root@master ~]# kubectl create deployment web --image=nginx --dry-run=client -o yaml > web5.yaml
[root@master ~]# vim web5.yaml        #编辑yaml文件
apiVersion: apps/v1
kind: Deployment
metadata:
    labels:
        app: web
    name: web
spec:
    replicas: 2
    selector:
        matchLabels:
            app: web
    template:
        metadata:
            labels:
                app: web
        spec:
            containers:
            - image: nginx
                name: nginx
[root@master ~]#
[root@master ~]# kubectl apply -f web5.yaml 
deployment.apps/web created
[root@master ~]# kubectl get pods     #确认pod的副本为2
NAME                   READY   STATUS    RESTARTS   AGE
web-5dcb957ccc-6pjvf   1/1     Running   0          70s
web-5dcb957ccc-hwcvt   1/1     Running   0          70s
[root@master ~]#                      #为web5.yaml中的pod创建service,同时再次编辑service5.yaml文件
[root@master ~]# vim service5.yaml 
apiVersion: v1
kind: Service
metadata:
    name: web                        #service的名称通常与deploy名字一致，方便识别
spec:
    ports:
    - port: 80
        protocol: TCP
        targetPort: 80
    selector:
        app: web                     #这里标签匹配的是web,与web5.yaml中pod的标签一致，所以写这个server之前
                                                                          #要确认deploy中pod的标签是什么，查看方法下面有介绍
[root@master ~]# 
                                     #可以查看deployment的web5.yaml文件中的15行,即deply的标签
                                     #也可以用指令查看pod的标签
[root@master ~]# kubectl  get pods --show-labels
NAME                   READY   STATUS    RESTARTS   AGE   LABELS
web-5dcb957ccc-6pjvf   1/1     Running   0          14m   app=web,pod-template-hash=5dcb957ccc
web-5dcb957ccc-hwcvt   1/1     Running   0          14m   app=web,pod-template-hash=5dcb957ccc
[root@master ~]# 

[root@master ~]# kubectl apply -f service5.yaml 
service/web created
[root@master ~]# kubectl get pod
NAME                   READY   STATUS    RESTARTS   AGE
web-5dcb957ccc-6pjvf   1/1     Running   0          18m
web-5dcb957ccc-hwcvt   1/1     Running   0          18m
[root@master ~]#                                        #查看server的clusterIP
[root@master ~]# kubectl get svc
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGE
web          ClusterIP   10.110.196.161   <none>        80/TCP    40s
[root@master ~]# 

                                     #查看web的后端IP地址，即web服务器集群的真实IP地址：
                                     #10.244.2.238:80,10.244.2.239:80，这两个地址也正是
                                     #VIP 10.110.196.161的后端IP地址
[root@master ~]# kubectl get endpoints  web
NAME   ENDPOINTS                         AGE
web    10.244.2.238:80,10.244.2.239:80   12m
[root@master ~]# 
[root@master ~]# kubectl get pod -o wide
NAME                   READY   STATUS    RESTARTS   AGE   IP             NODE    
web-5dcb957ccc-6pjvf   1/1     Running   0          31m   10.244.2.239   node2   
web-5dcb957ccc-hwcvt   1/1     Running   0          31m   10.244.2.238   node2   
[root@master ~]# 

                                                                          #注意：这里的CLUSTER-IP 10.110.196.161是供集群内部使用的一个VIP,这个
                                                                           #地址没有绑定在具体的设备上，所以是ping不通的。但在集群内部可以通过   
                                                                           # http://10.110.196.161来访问web

[root@node1 ~]# curl 10.110.196.161
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
        body {
                width: 35em;
                margin: 0 auto;
                font-family: Tahoma, Verdana, Arial, sans-serif;
        }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
                #在master节点访问会很慢，是kubeadmi集群自身的原因
[root@master ~]# curl 10.110.196.161
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>

		                                                              #把service的类型修改为NodePort
[root@master ~]# vim service5.yaml 
apiVersion: v1
kind: Service
metadata:
    name: web
spec:
    ports:
    - port: 80
        protocol: TCP
        targetPort: 80
    selector:
        app: web
    type: NodePort                #如果没有这一行默认是Cluster-IP
[root@master ~]# kubectl apply -f service5.yaml 
service/web configured
[root@master ~]#                                    #service的类型已修改为了NodePort,但是Cluster-IP仍会被创建
                                                                    #PORT(S)中多了一个30470这个端口是Node的端口，并且每个Node上都会被开启
[root@master ~]# kubectl get svc web
NAME   TYPE       CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
web    NodePort   10.110.196.161   <none>        80:30470/TCP   26h
[root@master ~]# 

在Node上查看端口
[root@master ~]# netstat -natlp  | grep 30470
tcp        0      0 0.0.0.0:30470           0.0.0.0:*               LISTEN      1606/kube-proxy     
[root@master ~]# 
[root@node1 ~]# netstat -natlp  | grep 30470
tcp        0      0 0.0.0.0:30470           0.0.0.0:*               LISTEN      1293/kube-proxy     
[root@node1 ~]# 

[root@master ~]# kubectl get node -o wide
NAME     STATUS   ROLES    AGE    VERSION   INTERNAL-IP    EXTERNAL-IP   OS-IMAGE                KERNEL-VERSION          CONTAINER-RUNTIME
master   Ready    master   246d   v1.18.0   192.168.1.61   <none>        CentOS Linux 7 (Core)   3.10.0-862.el7.x86_64   docker://18.6.1
node1    Ready    <none>   246d   v1.18.0   192.168.1.62   <none>        CentOS Linux 7 (Core)   3.10.0-862.el7.x86_64   docker://18.6.1
node2    Ready    <none>   246d   v1.18.0   192.168.1.63   <none>        CentOS Linux 7 (Core)   3.10.0-862.el7.x86_64   docker://18.6.1
[root@master ~]#

指定NodePort的端口，添加第10行
    1 apiVersion: v1
    2 kind: Service
    3 metadata:
    4     name: web
    5 spec:
    6     ports:
    7     - port: 80
    8         protocol: TCP
    9         targetPort: 80
   10         nodePort: 30008
   11     selector:
   12         app: web
   13     type: NodePort
[root@master ~]#
[root@master ~]# kubectl apply -f service5.yaml 
service/web configured
[root@master ~]# kubectl get svc
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
web          NodePort    10.110.196.161   <none>        80:30008/TCP   4d2h
[root@master ~]#