Kubernetes service 使用定义Kubernetes service 使用定义

Kubernetes service 使用定义

介绍说明

• 防止Pod失联
• 定义一组Pod的访问策略
• 支持ClusterIP，NodePort以及LoadBalancer三种类型
• Service的底层实现主要有Iptables和IPVS二种网络模式

Pod与Service的关系

• 通过label-selector相关联
• 通过Service实现Pod的负载均衡（ TCP/UDP 4层）

Service 定义

复制代码# 版本 apiVersion: v1 # 资源对象 kind: Service # 元数据 metadata: # 指定service名称 name: my-service # 命名空间 namespace: default spec: # 分配IP clusterIP: 10.0.0.1 # 指定端口 ports: # 端口名称 - name: http # 指定service端口 port: 80 # service使用协议 protocol: TCP # 容器端口，转发后端容器端口 targetPort: 80 # 标签选择器，通过标签匹配关联的pod selector: # 标签 app: nginx

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# 版本
apiVersion: v1
# 资源对象
kind: Service
# 元数据
metadata:
  # 指定service名称
  name: my-service
  # 命名空间
  namespace: default
spec:
  # 分配IP
  clusterIP: 10.0.0.1
  # 指定端口
  ports:
  # 端口名称
  - name: http
    # 指定service端口
    port: 80
    # service使用协议
    protocol: TCP
    # 容器端口，转发后端容器端口
    targetPort: 80
  # 标签选择器，通过标签匹配关联的pod
  selector:
    # 标签
    app: nginx

实例

1、创建service yml文件

复制代码apiVersion: v1 kind: Service metadata: name: my-service namespace: default spec: clusterIP: 10.0.0.123 ports: - name: http port: 80 protocol: TCP targetPort: 80 selector: app: nginx

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apiVersion: v1
kind: Service
metadata:
  name: my-service
  namespace: default
spec:
  clusterIP: 10.0.0.123
  ports:
  - name: http
    port: 80
    protocol: TCP
    targetPort: 80
  selector:
    app: nginx

2、创建service

复制代码kubectl apply -f service.yaml

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kubectl apply -f service.yaml

3、查看创建的service

复制代码NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE my-service ClusterIP 10.0.0.123 <none> 80/TCP 36s

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NAME             TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)        AGE
my-service       ClusterIP   10.0.0.123   <none>        80/TCP         36s

4、动态感知查看分配到的Node

复制代码NAME ENDPOINTS AGE kubernetes 192.168.1.108:6443,192.168.1.109:6443 2d16h my-service <none> 2m54s nginx-service 172.17.1.2:80,172.17.1.3:80,172.17.1.6:80 44h nginx-service2 <none> 17h

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NAME             ENDPOINTS                                   AGE
kubernetes       192.168.1.108:6443,192.168.1.109:6443       2d16h
my-service       <none>                                      2m54s
nginx-service    172.17.1.2:80,172.17.1.3:80,172.17.1.6:80   44h
nginx-service2   <none>                                      17h

注：每个service对应一个ENDPOINTS控制器，service则用来关联pod。

5、查看ENDPOINTS详细信息

复制代码Name: my-service Namespace: default Labels: <none> Annotations: kubectl.kubernetes.io/last-applied-configuration: {"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"name":"my-service","namespace":"default"},"spec":{"clusterIP":"10.0.0.12... Selector: app=nginx Type: ClusterIP IP: 10.0.0.123 Port: http 80/TCP TargetPort: 80/TCP Endpoints: <none> Session Affinity: None Events: <none>

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Name:              my-service
Namespace:         default
Labels:            <none>
Annotations:       kubectl.kubernetes.io/last-applied-configuration:
                     {"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"name":"my-service","namespace":"default"},"spec":{"clusterIP":"10.0.0.12...
Selector:          app=nginx
Type:              ClusterIP
IP:                10.0.0.123
Port:              http  80/TCP
TargetPort:        80/TCP
Endpoints:         <none>
Session Affinity:  None
Events:            <none>