Ruby with RabbitMQ and LavinMQ

We recommend amqp-client.rb. It reconnects automatically, recovers your consumers after a reconnect, and has no dependencies.

gem install amqp-client

Publish and consume

Set BROKER_URL to the AMQP URL from your instance’s details page in the CloudAMQP console. Without it, the examples connect to a local broker.

Save the connection helper as amqp.rb:

require "amqp-client"

module Amqp
  def self.client
    AMQP::Client.new(ENV.fetch("BROKER_URL", "amqp://guest:guest@localhost")).start
  end
end

Save the publisher as publisher.rb:

require_relative "amqp"

module Publisher
  # Messages are persistent and wait for a publisher confirm by default
  def self.publish(client, queue, message)
    client.queue(queue).publish(message)
    puts " [x] Sent #{message.inspect}"
  end
end

if __FILE__ == $PROGRAM_NAME
  client = Amqp.client
  Publisher.publish(client, "hello", "Hello world!")
  client.stop
end

Save the consumer as worker.rb in the same directory:

require_relative "amqp"

module Worker
  # The message is acked when the block returns, and requeued if it raises
  def self.consume(client, queue, &handler)
    client.queue(queue).subscribe(prefetch: 10) do |msg|
      handler.call(msg.body)
    end
  end
end

if __FILE__ == $PROGRAM_NAME
  client = Amqp.client
  Worker.consume(client, "hello") { |message| puts " [x] Received #{message.inspect}" }
  puts " [*] Waiting for messages. To exit press CTRL+C"
  begin
    sleep
  rescue Interrupt
    client.stop
  end
end

Run ruby worker.rb in one terminal and ruby publisher.rb in another.

A runnable example is in ruby/amqp-client in cloudamqp/examples.

Good to know

Connect with the URL. AMQP::Client.new(url).start, where the URL is the one on your instance’s details page in the CloudAMQP console.
Messages are safe by default. publish sends persistent messages and waits until the broker has confirmed them.
Messages are acked after your block returns. If the block raises, the message is requeued. Make your handler idempotent, because a message can be delivered again after a reconnect.
Set a prefetch limit when you subscribe, e.g. subscribe(prefetch: 10), so a consumer doesn’t buffer more messages than it can handle.
Use amqps:// to connect over TLS. The server certificate is verified.

See the amqp-client.rb README for codecs, RPC and the low-level API.

Other Ruby libraries

Bunny, a widely used synchronous client
March Hare, for JRuby, built on the RabbitMQ Java client
Kicks (formerly Sneakers), a background job framework
Hutch, for inter-service communication

Video tutorial

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