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Simple RabbitMQ Subscriber Using Bunny

This is a very simple example of an RabbitMQ subscriber in Ruby using the bunny gem. It uses the dead_letter pattern to resend failures to another queue if processing fails. The original message is ack'd so it does not get reprocessed. Something else probably needs to be monitoring the messages on the dead_letter queue.

Signal.trap('INT') { @subscriber.shutdown }
Signal.trap('TERM') { @subscriber.shutdown }

class Subscriber
  def initialize
    @bunny = Bunny.new(...)
    @queue = ...
    @dead_letter = ...
  end
  
  def run
    @queue.subscribe(:ack => true) do |msg|
      payload = JSON.parse(msg[:payload])
      begin
        do_something_with_the_payload(payload)
      rescue StandardError, Timeout::Error => error
        routing_key = msg[:delivery_details][:routing_key]
        @dead_letter.publish(payload, :key => routing_key)
      end
    end
  end

  def shutdown
    @queue.unsubscribe rescue nil
    @bunny.stop rescue nil
    exit
  end
end

@subscriber = Subscriber.new
@subscriber.run