Finishing the consumer side of the alert example from chapter 4

sylvilagus/jruby/Gemfile

@@ -1,6 +1,7 @@
 source :rubygems
 
 gem 'json_pure'
+gem 'jruby-openssl'
 
 group :development, :test do
   gem 'rspec'

sylvilagus/jruby/Gemfile.lock

@@ -1,7 +1,10 @@
 GEM
   remote: http://rubygems.org/
   specs:
+    bouncy-castle-java (1.5.0146.1)
     diff-lcs (1.1.3)
+    jruby-openssl (0.7.7)
+      bouncy-castle-java (>= 1.5.0146.1)
     json_pure (1.7.5)
     rspec (2.12.0)
       rspec-core (~> 2.12.0)
@@ -16,5 +19,6 @@ PLATFORMS
   java
 
 DEPENDENCIES
+  jruby-openssl
   json_pure
   rspec

sylvilagus/jruby/lib/sylvilagus/ch04/alert_consumer.rb

@@ -0,0 +1,93 @@
+require 'sylvilagus/init'
+require 'sylvilagus/ch04'
+require 'json'
+require 'net/smtp'
+require 'rabbitmq-client.jar'
+
+class Sylvilagus::Ch04::AlertProducer
+  OPS_EMAILS = ['me@localhost'].freeze
+  ADMIN_EMAILS = ['me@localhost'].freeze
+
+  def self.send_email(recipients, subject, body)
+    Net::SMTP.start('localhost', 25) do |smtp|
+      msgstr = <<-EOM.gsub(/^      /, '')
+      To: #{recipients.join(', ')}
+      From: alerts@sylvilagus.local
+      Subject: #{subject}
+      Date: #{Time.now}
+
+      #{body}
+      EOM
+      smtp.send_message(msgstr, 'alerts@sylvilagus.local', recipients)
+    end
+  end
+
+  class CriticalNotifier < Java::ComRabbitmqClient::DefaultConsumer
+    def handleDelivery(consumer_tag, envelope, properties, body)
+      message = JSON.parse(
+        Java::OrgJruby::RubyString.bytes_to_string(body)
+      ).fetch('message')
+
+      Sylvilagus::Ch04::AlertProducer.send_email(
+        OPS_EMAILS, 'CRITICAL ALERT!', message
+      )
+      puts "Sent alert via email! Alert text: #{message}"
+      puts "Recipients: #{OPS_EMAILS}"
+
+      channel.basic_ack(envelope.delivery_tag, false)
+    end
+  end
+
+  class RateLimitNotifier < Java::ComRabbitmqClient::DefaultConsumer
+    def handleDelivery(consumer_tag, envelope, properties, body)
+      message = JSON.parse(
+        Java::OrgJruby::RubyString.bytes_to_string(body)
+      ).fetch('message')
+
+      Sylvilagus::Ch04::AlertProducer.send_email(
+        ADMIN_EMAILS, 'RATE LIMIT ALERT!', message
+      )
+      puts "Sent alert via email! Alert text: #{message}"
+      puts "Recipients: #{ADMIN_EMAILS}"
+
+      channel.basic_ack(envelope.delivery_tag, false)
+    end
+  end
+
+  def main
+    factory = Java::ComRabbitmqClient::ConnectionFactory.new
+    factory.uri = ENV.fetch('SYLVILAGUS_ALERT_AMQP_URI')
+    @conn = factory.new_connection
+    channel = @conn.create_channel
+
+    channel.exchange_declare('alerts', 'topic', true, false, false, nil)
+    channel.queue_declare('critical', true, false, false, nil)
+    channel.queue_bind('critical', 'alerts', 'critical.*', nil)
+    channel.queue_declare('rate_limit', true, false, false, nil)
+    channel.queue_bind('rate_limit', 'alerts', '*.rate_limit', nil)
+
+    critical_notifier = CriticalNotifier.new(channel)
+    rate_limit_notifier = RateLimitNotifier.new(channel)
+
+    channel.basic_consume(
+      'critical', false, 'critical', critical_notifier
+    )
+    channel.basic_consume(
+      'rate_limit', false, 'rate_limit', rate_limit_notifier
+    )
+
+    trap(:INT) { exit 0 }
+
+    puts 'Starting consumer loop...'
+    loop { sleep 1 }
+  ensure
+    begin
+      @conn.close if @conn
+    rescue NativeException
+    end
+  end
+end
+
+if $0 == __FILE__
+  Sylvilagus::Ch04::AlertProducer.new.main
+end