关于kubernetes:Kubernetes-endpoints资源类型——映射外部服务

endpoints是一种kubernetes资源类型，它是namespace scoped，简写为ep:

kubectl api-resources|grep endpoints
endpoints                         ep                                          true         Endpoints

endpoints有两种应用办法：

• 随service被创立：
  • 创立service对象的同时，kubernetes会创立同名的endpoints的对象；
  • service的podSelector会将指标pod的endpoint信息(ip/port)，增加到endpoints对象中；
• 独立创立endpoints：
  • enpdoints作为一种资源类型，反对用户创立；
  • 将内部服务的endpoint增加到endpoints对象，能够应用kubernetes service拜访内部服务；

service与endpoints

以一个简略的例子，来演示endpoints随service被主动创立进去。
创立nginx deploy，含2个pod:

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: nginx
  name: nginx
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:latest
        imagePullPolicy: IfNotPresent
        command:
        - nginx
        - -g
        - "daemon off;"
        workingDir: /usr/share/nginx/html
        ports:
        - name: http
          containerPort: 80
          protocol: TCP

创立nginx service:

apiVersion: v1
kind: Service
metadata:
  name: nginx-svc
spec:
  ports:
  - port: 80
    targetPort: 80
  selector:
    app: nginx

查看其service和endpoints资源：有一个同名的endpoints被创立进去

# kubectl get svc,endpoints
NAME                 TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE
service/nginx-svc    ClusterIP   10.233.26.39   <none>        80/TCP    3m2s

NAME                   ENDPOINTS                                                       AGE
endpoints/nginx-svc    10.233.96.113:80,10.233.97.95:80                3m2s

其endpoints的内容，理论是nginx pod的ip+port:

# kubectl get pod -owide
NAME                    READY   STATUS    RESTARTS   AGE    IP              NODE      NOMINATED NODE   READINESS GATES
nginx-6dcdfd5b8-8q7l5   1/1     Running   0          4m3s   10.233.97.95    master1   <none>           <none>
nginx-6dcdfd5b8-xsl96   1/1     Running   0          4m3s   10.233.96.113   master3   <none>           <none>

内部服务与endpoints

手动创立endpoints，增加内部服务的endpoint，能够将内部服务作为kubernetes的service应用。
etcd有3节点部署在内部，为其创立service: etcd-k8s，不指定podSelector：

apiVersion: v1
kind: Service
metadata:
  name: etcd-k8s
  namespace: kube-system
spec:
  type: ClusterIP
  ports:
  - name: port
    port: 2379
    protocol: TCP

创立同名的endpoints资源: etcd-k8s，将etcd节点的ip+port填进去：

apiVersion: v1
kind: Endpoints
metadata:
  name: etcd-k8s
  namespace: kube-system
subsets:
- addresses:
  - ip: 178.104.163.38
    nodeName: etc-master1
  - ip: 178.104.163.187
    nodeName: etc-master2
  - ip: 178.104.163.243
    nodeName: etc-master3
  ports:
  - name: port
    port: 2379
    protocol: TCP

这样，通过serviceName.namespace:port就能够在kubernetes集群内拜访内部的etcd服务：