Specify network type for Pods

Once a Pod's network type is specified, it will always be created with the resources of specified type. The "networking.alibaba.com/network-type" annotation of Pods can be used to do this. Two types is available now, Overlay or Underlay.

For example:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: curl-deployment
spec:
  selector:
    matchLabels:
      app: curl
  replicas: 6
  template:
    metadata:
      annotations:
        networking.alibaba.com/network-type: Overlay       # All the Pods created by this deployment will be overlay.
      labels:
        app: curl
    spec:
      containers:
      - args:
        - -c
        - sleep 999999999
        command:
        - /bin/sh
        name: curl
        image: tutum/curl:alpine