ingress用于集群内部服务暴露到外部环境访问，它是一组请求路由规则的集合。
```
apiVersion: extensions/v1beta1
kind: Ingress

metadata:
  name: demo-ingress
  namespace: demo-ns
  labels:
    name: demo-ingress
    version: v1
spec:
  rules:
  - host: test.demo.com
    http:
      paths:
      - path: /
        backend:
        serviceName: demo-svc1
        servicePort: 80
```