k8s入门实战-Service

Service 和 Label

Service 通过一组 Pod 路由通信。Service 是一种抽象，它允许 Pod 死亡并在 Kubernetes 中复制，而不会影响应用程序。在依赖的 Pod (如应用程序中的前端和后端组件)之间进行发现和路由是由Kubernetes Service 处理的。

Service 匹配一组 Pod 是使用标签(Label)和选择器(Selector), 它们是允许对 Kubernetes 中的对象进行逻辑操作的一种分组原语。标签(Label)是附加在对象上的键/值对，可以以多种方式使用:
在这里插入图片描述

指定用于开发，测试和生产的对象
嵌入版本标签
使用 Label 将对象进行分类

执行yaml文件

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
  namespace: dev
spec:
  replicas: 3
  selector:
    matchLabels:
      run: nginx
  template:
    metadata:
      labels:
        run: nginx
    spec:
      containers:
      - image: nginx:1.17.1
        name: nginx
        ports:
        - containerPort: 80
          protocol: TCP

[root@master ~]# kubectl create -f deploy-nginx.yaml
deployment.apps/nginx created
[root@master ~]# kubectl get pods -n dev
NAME                     READY   STATUS    RESTARTS   AGE
nginx-64777cd554-h6rjh   1/1     Running   0          11s
nginx-64777cd554-sffwm   1/1     Running   0          11s
nginx-64777cd554-zw66q   1/1     Running   0          11s

查询每个podIP地址

[root@master ~]# kubectl get pods -n dev -o wide
NAME                     READY   STATUS    RESTARTS   AGE    IP            NODE    NOMINATED NODE   READINESS GATES
nginx-64777cd554-h6rjh   1/1     Running   0          117s   10.244.2.17   node2   <none>           <none>
nginx-64777cd554-sffwm   1/1     Running   0          117s   10.244.2.18   node2   <none>           <none>
nginx-64777cd554-zw66q   1/1     Running   0          117s   10.244.1.10   node1   <none>           <none>

删除pod，查看新pod Ip地址是否改变

[root@master ~]# kubectl delete pod nginx-64777cd554-h6rjh -n dev
pod "nginx-64777cd554-h6rjh" deleted
[root@master ~]# kubectl get pods -n dev -o wide
NAME                     READY   STATUS    RESTARTS   AGE     IP            NODE    NOMINATED NODE   READINESS GATES
nginx-64777cd554-qdjn8   1/1     Running   0          45s     10.244.1.11   node1   <none>           <none>
nginx-64777cd554-sffwm   1/1     Running   0          4m59s   10.244.2.18   node2   <none>           <none>
nginx-64777cd554-zw66q   1/1     Running   0          4m59s   10.244.1.10   node1   <none>           <none>

删除pod后，新建pod IP改变

Pod IP在Pod重建时会更改
Pod IP 只能在集群内使用，外部无法访问

Kubernetes 中 Service 是将运行在一个或一组 Pod 上的网络应用程序公开为网络服务的方法。

Service在生命周期内，IP地址不会改变

创建集群内部可访问的Service

#暴露Service  
[root@master ]# kubectl expose deployment nginx --name=svc-nginx1 --type=ClusterIP --port=80 --target-port=80 -n dev
service/svc-nginx1 exposed 
[root@master ~]# kubectl get svc -n dev
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
svc-nginx1   ClusterIP   10.101.232.58   <none>        80/TCP    5m55s
#访问service IP+端口

这里我无法ping通Service IP

错误：ServiceIP无法Ping通

我的做法尝试重新启动Pod，重新创建一个Service

然后编辑文件

kubectl -n kube-system edit configmap kube-proxy

修改这段

  kind: KubeProxyConfiguration
    metricsBindAddress: ""
    mode: "ipvs"
    nodePortAddresses: null

把mode添加为ipvs

重启主机即可

然后查看下新的ServiceIP，访问80端口,成功访问，但是很慢，不报错的话你等个一分钟看看

[root@master ~]# kubectl get pods,svc,deploy -n dev
NAME                         READY   STATUS    RESTARTS   AGE
pod/nginx-64777cd554-bhs6f   1/1     Running   0          4m39s
pod/nginx-64777cd554-gkjqk   1/1     Running   0          4m39s
pod/nginx-64777cd554-x5szs   1/1     Running   0          4m39s

NAME                 TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
service/svc-nginx1   ClusterIP   10.108.90.241   <none>        80/TCP    3m7s

NAME                    READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/nginx   3/3     3            3           4m39s
[root@master ~]# curl 10.108.90.241:80
<!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>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

创建集群外部也可以访问的Service

# 上面创建的Service的type类型为ClusterIP，这个ip地址只用集群内部可访问
# 如果需要创建外部也可以访问的Service，需要修改type为NodePort
[root@master ~]# kubectl expose deploy nginx --name=svc-nginx2 --type=NodePort --port=80 --target-port=80 -n dev
service/svc-nginx2 exposed  

[root@master ~]# kubectl get svc -n dev
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
svc-nginx1   ClusterIP   10.108.90.241   <none>        80/TCP         9m27s
svc-nginx2   NodePort    10.96.231.201   <none>        80:32400/TCP   18s

尝试浏览器访问：
在这里插入图片描述

删除Service

#删除所有
[root@master ~]# kubectl delete svc -n dev --all
service "svc-nginx1" deleted
service "svc-nginx2" deleted

#删除单个
kubectl delete svc [Service名称] -n [名称空间]

配置方式

创建一个svc-nginx.yaml

apiVersion: v1
kind: Service
metadata:
  name: svc-nginx
  namespace: dev
spec:
  clusterIP: 10.109.179.231
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  selector:
    run: nginx
  type: ClusterIP

#创建
[root@master ~]# kubectl create -f svc-nginx.yaml
service/svc-nginx created
[root@master ~]# kubectl get svc -n dev
NAME        TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGE
svc-nginx   ClusterIP   10.109.179.231   <none>        80/TCP    49s
#删除
[root@master ~]# kubectl delete -f svc-nginx.yaml
service "svc-nginx" deleted
[root@master ~]# kubectl get svc -n dev
No resources found in dev namespace.