return_handler.rb

require 'bunny'

connection = Bunny.new
connection.start

channel = connection.create_channel
queue = channel.queue('hello-ret')
exch = channel.default_exchange

exch.on_return do |return_info, properties, content|
  puts "Got a returned message : #{content}"
  puts return_info.inspect
  puts properties.inspect
  message = content
end

exch.publish('Hello World!', routing_key: rand.to_s, mandatory: true)

sleep 2