eip_sparkle.rb

  resources(:my_eni) do
    type 'AWS::EC2::NetworkInterface'
    properties do
      subnet_id ref!(:my_subnet_id)
      group_set [ref!(:my_security_group)]
    end
  end

  resources(:my_eip) do
    type 'AWS::EC2::EIP'
    properties do
      domain 'vpc'
    end
  end
  
 resources(:my_instance) do
   type 'AWS::EC2::Instance'
   properties do
    # other properties here
    network_interfaces array!(
      -> {
        device_index 0
        network_interface_id ref!(:my_eni)
      }
    )
   end
 end