k8s 使用 Service 控制器对外暴露服务

Service 引入主要是解决 Pod 的动态变化，提供统一访问入口：

防止 Pod 失联，准备找到提供同一个服务的 Pod （服务发现） 定义一组 Pod 的访问策略 （负载均衡）

kubectl apply -f deploy.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: chiyi-nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: chiyi-nginx
  template:
    metadata:
      labels:
        app: chiyi-nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

kubectl apply -f service.yaml

apiVersion: v1
kind: Service
metadata:
  name: chiyi-nginx
spec:
  selector:
    app: chiyi-nginx
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80
      nodePort: 30002
  type: NodePort

kubectl  get ep
curl 10.244.1.58:80

说明：

Service 通过标签关联一组 Pod

Service 为一组 Pod 提供负载均衡能力

[root@k8s-master service]# kubectl get ep
NAME          ENDPOINTS                                      AGE
chiyi-nginx   10.244.1.58:80,10.244.1.59:80,10.244.2.46:80   5m19s
kubernetes    172.17.28.225:6443                             23h
[root@k8s-master service]# curl 10.244.1.58:80





    body {
        width: 35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }



Welcome to nginx!
If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.

For online documentation and support please refer to
nginx.org.

Commercial support is available at
nginx.com.

Thank you for using nginx.

kubectl  get service
curl 10.101.104.218

[root@k8s-master service]# kubectl get service
NAME          TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
chiyi-nginx   NodePort    10.101.104.218           80:30002/TCP   6m3s
kubernetes    ClusterIP   10.96.0.1                443/TCP        23h
[root@k8s-master service]# curl 10.101.104.218





    body {
        width: 35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }



Welcome to nginx!
If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.

For online documentation and support please refer to
nginx.org.

Commercial support is available at
nginx.com.

Thank you for using nginx.

ss -antp |grep 30002

[root@k8s-master service]# ss -antp |grep 30002
LISTEN     0      128          *:30002                    *:*                   users:(("kube-proxy",pid=3544,fd=13))

kubectl  get service chiyi-nginx -o yaml

kubectl get pods -l app=chiyi-nginx

[root@k8s-master service]# kubectl get pods -l app=chiyi-nginx
NAME                           READY   STATUS    RESTARTS   AGE
chiyi-nginx-5bbf8bff4b-6bwfz   1/1     Running   0          3m58s
chiyi-nginx-5bbf8bff4b-bpvvc   1/1     Running   0          3m58s
chiyi-nginx-5bbf8bff4b-pwwt4   1/1     Running   0          3m58s

kubectl scale deployment chiyi-nginx --replicas=1

kubectl  get service,pods,ep

ClusterIP 集群内部使用,任一节点服务器和 pod 内部都可以访问NodePort 对外暴露应用（端口默认范围：30000-32767），任一节点服务器公网IP+端口号，可在浏览器访问。LoadBalancer 对外暴露应用，适合公有云