code: func (agent *ecsAgent) getHostPublicIPv4AddressFromEC2Metadata() string {
  	// Get instance ID from ec2 metadata client.
  	hostPublicIPv4Address, err := agent.ec2MetadataClient.PublicIPv4Address()
  	if err != nil {
  		seelog.Errorf("Unable to retrieve Host Instance PublicIPv4 Address: %v", err)
  		return ""
  	}
  	return hostPublicIPv4Address
  }
docs: // getHostPublicIPv4AddressFromEC2Metadata will retrieve the PublicIPAddress (IPv4) of this
  // instance through the EC2 API