k8s的service和endpoint

service： 在k8s中，pod之间是通信是一般通过service名称完成的
endpoint: pod和service之间的关联关系，是通过endpoint实现的。Endpoint Endpoints表示了一个Service对应的所有Pod副本的访问地址，而Endpoints Controller负责生成和维护所有Endpoints对象的控制器。它负责监听Service和对应的Pod副本的变化。

对于pod，endpoint是集群自动创建的，用于将service和pod关联起来；而对于外部服务（部署在集群外边的数据库啥的），我们可以人工的创建endpoint和service。使其能够更规范的和pod进行通信。

这里主要记录一下endpoint和service的书写规则。两种场景：

[root@10-9-71-11 ~]# cat redis.yaml 
kind: Endpoints
apiVersion: v1
metadata:
  name: redis-cluster
subsets:
  - addresses:
      - ip: 10.130.25.161
      - ip: 10.130.25.162
      - ip: 10.130.25.163 
    ports:
      - port: 6379
---
kind: Service
apiVersion: v1
metadata:
  name: redis-cluster
spec:
  ports:
    - protocol: TCP
      port: 6379
      targetPort: 6379

[root@10-9-71-11 ~]# kubectl describe endpoints redis-cluster
Name:         redis-cluster
Namespace:    default
Labels:       
Annotations:  kubectl.kubernetes.io/last-applied-configuration:
                {"apiVersion":"v1","kind":"Endpoints","metadata":{"annotations":{},"name":"redis-cluster","namespace":"default"},"subsets":[{"addresses":[...
Subsets:
  Addresses:          10.130.25.161,10.130.25.162,10.130.25.163
  NotReadyAddresses:  
  Ports:
    Name     Port  Protocol
    ----     ----  --------
      6379  TCP

Events:  
[root@10-9-71-11 ~]# kubectl describe svc redis-cluster
Name:              redis-cluster
Namespace:         default
Labels:            
Annotations:       kubectl.kubernetes.io/last-applied-configuration:
                     {"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"name":"redis-cluster","namespace":"default"},"spec":{"ports":[{"port":63...
Selector:          
Type:              ClusterIP
IP:                10.0.147.90
Port:                6379/TCP
TargetPort:        6379/TCP
Endpoints:         10.130.25.161:6379,10.130.25.162:6379,10.130.25.163:6379
Session Affinity:  None
Events:            

[root@10-9-71-11 ~]# kubectl get endpoints redis-cluster
NAME            ENDPOINTS                                                  AGE
redis-cluster   10.130.25.161:6379,10.130.25.162:6379,10.130.25.163:6379   2m3s
[root@10-9-71-11 ~]# 
[root@10-9-71-11 ~]# kubectl get svc redis-cluster
NAME            TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)    AGE
redis-cluster   ClusterIP   10.0.147.90           6379/TCP   2m16s

[root@10-9-71-11 ~]# cat  redis.yaml 
kind: Endpoints
apiVersion: v1
metadata:
  name: redis
subsets:
  - addresses:
      - ip: 10.130.25.161 
    ports:
      - name: port1
        port: 26379
      - name: port2
        port: 26380
      - name: port3
        port: 26381
---
kind: Service
apiVersion: v1
metadata:
  name: redis
spec:
  ports:
    - name: port1
      protocol: TCP
      port: 26379
      targetPort: 26379
    - name: port2
      protocol: TCP
      port: 26380
      targetPort: 26380
    - name: port3
      protocol: TCP
      port: 26381
      targetPort: 26381 

使用多个端口时，端口必须有名字多端口之间通过列表的形式展现 查看servcie和endpoint详情,可看到ip和端口的对应关系

[root@10-9-71-11 ~]# kubectl describe  endpoints redis
Name:         redis
Namespace:    default
Labels:       
Annotations:  kubectl.kubernetes.io/last-applied-configuration:
   #             {"apiVersion":"v1","kind":"Endpoints","metadata":{"annotations":{},"name":"redis","namespace":"default"},"subsets":[{"addresses":[{"ip":"1...}]
Subsets:
  Addresses:          10.130.25.161
  NotReadyAddresses:  
  Ports:
    Name   Port   Protocol
    ----   ----   --------
    port3  26381  TCP
    port2  26380  TCP
    port1  26379  TCP

Events:  
--------------------------------------------------
[root@10-9-71-11 ~]# kubectl describe  service  redis
Name:              redis
Namespace:         default
Labels:            
Annotations:       kubectl.kubernetes.io/last-applied-configuration:
                     {"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"name":"redis","namespace":"default"},"spec":{"ports":[{"name":"port1","p...
Selector:          
Type:              ClusterIP
IP:                10.0.92.98
Port:              port1  26379/TCP
TargetPort:        26379/TCP
Endpoints:         10.130.25.161:26379
Port:              port2  26380/TCP
TargetPort:        26380/TCP
Endpoints:         10.130.25.161:26380
Port:              port3  26381/TCP
TargetPort:        26381/TCP
Endpoints:         10.130.25.161:26381
Session Affinity:  None
Events:            

[root@10-9-71-11 ~]# kubectl get endpoints redis
NAME    ENDPOINTS                                                     AGE
redis   10.130.25.161:26381,10.130.25.161:26380,10.130.25.161:26379   48m
[root@10-9-71-11 ~]# kubectl get svc redis
NAME    TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)                         AGE
redis   ClusterIP   10.0.92.98           26379/TCP,26380/TCP,26381/TCP   49m