AWS Status Checker

awspoller.rb

require 'nokogiri'
require 'open-uri'
require './notifier'

@notifier = EmailNotifier.new
@error_level = 0
@watched_feeds = [
  'http://status.aws.amazon.com/rss/ec2-us-east-1.rss',
  'http://status.aws.amazon.com/rss/rds-us-east-1.rss',
  'http://status.aws.amazon.com/rss/simpledb-us-east-1.rss',
  'http://status.aws.amazon.com/rss/management-console.rss'
]

def upgrade_error(new_level)
  if new_level > @error_level
    @error_level = new_level
  end
end

@notifier.colour(BLUE)

loop do
  puts "Polling... #{Time.now}"
  @error_level = 0
  @watched_feeds.each do |feed|
    open(feed) do |rss|
      xml_doc  = Nokogiri::XML(rss)
      latest_status = xml_doc.css("item title").first.text
      case latest_status
        when /^Informational message/i
          upgrade_error(1)
        when /^Performance issues/i
          upgrade_error(2)
        when /^Service disruption/i
          upgrade_error(3)
        end
    end
  end
  print "Polling Completed. "
  case @error_level
  when 0
    puts "OK"
    @notifier.colour(GREEN)
  when 1
    puts "INFO"
    @notifier.colour(YELLOW)
  when 2
    puts "PERF"
    @notifier.colour(ORANGE)
  when 3
    puts "OUTAGE"
    @notifier.colour(RED)
  end
  sleep 240
end

Gemfile

source :rubygems
gem 'libusb'
gem 'nokogiri'

notifier.rb

require 'libusb'

class Colour
  attr_reader :red, :green, :blue

  def initialize(red, green, blue)
     @red = red
     @green = green
     @blue = blue
  end

  def hex_string
    hexify(@red, @green, @blue)
  end

  def max_val
    [@red, @green, @blue].max
  end

  private

  def hexify(*items)
    items.collect! { |x| x.chr }.join
  end
end

WHITE = Colour.new(64, 64, 64)
RED = Colour.new(64, 0, 0)
GREEN = Colour.new(0, 64, 0)
BLUE = Colour.new(0, 0, 64)
MAGENTA = Colour.new(64, 0, 64)
YELLOW = Colour.new(64,64,0)
ORANGE = Colour.new(64,32,0)
CYAN   = Colour.new(0,64,64)
OFF = Colour.new(0, 0, 0)

class EmailNotifier
  def initialize
    usb_context = LIBUSB::Context.new
    # The hex value for Dream Cheeky on the device. Assuming only the email notifier is attached
    @device = usb_context.devices(:idVendor => 0x1d34).first
    reset_device
  end

  def colour!(colour)
    @colour = colour
    send(colour.hex_string + "\x00\x00\x00\x00\x05")  # The 5 extra bytes apparently need to be sent
  end

  def colour(colour)
    return true             if @colour == colour
    return colour!(colour)  if @colour.nil?
    mix_colours(@colour,colour).each do |i|
      colour!(i)
      sleep 0.01
    end
    colour! colour
    @colour = colour
  end

  def turn_off
    colour!(Colour.new(0, 0, 0))
  end

  private
  def send(data)
    @device.open do |handle|
      request_type = LIBUSB::REQUEST_TYPE_CLASS | LIBUSB::RECIPIENT_INTERFACE  # flags to send data to device
      # other special flags that I don't know what they do
      handle.control_transfer(:bmRequestType => request_type, :bRequest => 0x09, :wValue => 0x200, :wIndex => 0x00, :dataOut => data)
    end
  end

  # Special codes that apparently need to be sent to initialise the device.
  # The first three values of the last line also represent the RGB colours on initialisation
  def reset_device
    send "\x1f\x02\x00\x2e\x00\x00\x2b\x03"
    send "\x00\x02\x00\x2e\x00\x00\x2b\x04"
    send "\x00\x00\x00\x2e\x00\x00\x2b\x05"
  end

  def mix_colours(c1,c2)
    current_color = c1.is_a?(Colour) ? [c1.red,c1.blue,c1.green] : c1.dup
    destination   = c2.is_a?(Colour) ? [c2.red,c2.blue,c2.green] : c2.dup
    distance      = []
    until current_color == destination
      [0,1,2].each do |i|
        if current_color[i] > destination[i]
          current_color[i] -= 1
        elsif current_color[i] < destination[i]
          current_color[i] += 1
        end
      end
      distance << Colour.new(current_color[0],current_color[2],current_color[1])
    end
    distance
  end

  def limit_array(array,limit=150.0)
    rate = array.length / limit

    array.each_slice(rate.to_i).map(&:last)
  end
end