service

--pod-network-cidr=10.244.0.0/16 （pod网段）

--service-cidr=10.96.0.0/12 （service网段）

[root@master maintest]# cat pod.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-nginx
spec:
  selector:
    matchLabels:
      run: my-nginx
  replicas: 2
  template:
    metadata:
      labels:
        run: my-nginx
    spec:
      containers:
      - name: my-nginx
        image: nginx
        ports:
        - containerPort: 80

service 默认type类型为ClusterIP

[root@master maintest]# cat service.yaml
apiVersion: v1
kind: Service
metadata:
  name: my-nginx
  labels:
    run: my-nginx
spec:
  ports:
  - port: 80
    protocol: TCP
  selector:
    run: my-nginx

service 代理到对应的后端pod

映射到宿主机端口

.service.spec.type

​ NodePort

apiVersion: v1
kind: Service
metadata:
  name: my-nginx
  labels:
    run: my-nginx
spec:
  ports:
  - port: 80
    protocol: TCP
  type: NodePort
  selector:
    run: my-nginx

[root@master maintest]# kubectl get svc -o wide
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE   SELECTOR
kubernetes   ClusterIP   10.96.0.1        <none>        443/TCP        69d   <none>
my-nginx     NodePort    10.106.132.151   <none>        80:30994/TCP   21h   run=my-nginx

访问node节点的ip:30994---->service ip:80---->pod ip:80

创建没有selector的service

[root@master maintest]# cat noselector.yaml
apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 3306

endpoint.yaml

[root@master maintest]# cat endpoint.yaml
apiVersion: v1
kind: Endpoints
metadata:
  name: my-service
subsets:
- addresses:
  - ip: 1.2.3.4
  ports:
  - port: 3306

[root@master maintest]# kubectl describe svc my-service
Name:              my-service
Namespace:         default
Labels:            <none>
Annotations:       <none>
Selector:          <none>
Type:              ClusterIP
IP Families:       <none>
IP:                10.104.205.156
IPs:               <none>
Port:              <unset>  80/TCP
TargetPort:        3306/TCP
Endpoints:         1.2.3.4:3306
Session Affinity:  None
Events:            <none>

创建type是ExternalName的service

[root@master maintest]# cat external.yaml
apiVersion: v1
kind: Service
metadata:
  name: my-service
  namespace: prod
spec:
  type: ExternalName
  externalName: my.database.example.com