Class: HerokuMongoWatcher::Autoscaler

Inherits:
Object
  • Object
show all
Includes:
Singleton
Defined in:
lib/heroku_mongo_watcher/autoscaler.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Autoscaler

Returns a new instance of Autoscaler.



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# File 'lib/heroku_mongo_watcher/autoscaler.rb', line 10

def initialize()
  @last_scaled = Time.now - 60
  @options = default_options.merge(config)
end

Instance Attribute Details

#last_scaled ⇒ Object (readonly)

Returns the value of attribute last_scaled.



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# File 'lib/heroku_mongo_watcher/autoscaler.rb', line 8

def last_scaled
  @last_scaled
end

#options ⇒ Object (readonly)

Returns the value of attribute options.



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# File 'lib/heroku_mongo_watcher/autoscaler.rb', line 8

def options
  @options
end

Instance Method Details

#config ⇒ Object 



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# File 'lib/heroku_mongo_watcher/autoscaler.rb', line 25

def config
  HerokuMongoWatcher::Configuration.instance.config
end

#default_options ⇒ Object 



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# File 'lib/heroku_mongo_watcher/autoscaler.rb', line 15

def default_options
  {
      min_dynos: 6,
      max_dynos: 50,
      step: 5,
      requests_per_dyno: 1000,
      min_frequency: 60 # seconds
  }
end

#heroku ⇒ Object 



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# File 'lib/heroku_mongo_watcher/autoscaler.rb', line 72

def heroku
  @heroku ||= Heroku::Client.new(config[:heroku_username], config[:heroku_password])
end

#scale(data_row) ⇒ Object

should play it safe and add config to the calculated result if rpm > 10,000 scale to 15 if rpm > 15,000 scale to 20 if rpm > 20,000 scale to 25 if rpm then drops to 14,000 drop to 15 if rpm then drops to 300 drop to 6 (minimum)

also do not scale down for 5 minutes always allow to scale up



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# File 'lib/heroku_mongo_watcher/autoscaler.rb', line 38

def scale(data_row)

  rpm = data_row.total_requests
  current_dynos = data_row.dynos

  # 32,012 rpm => 32 dynos
  ideal_dynos = (rpm / options[:requests_per_dyno]).round

  # return if the delta is less than 5 dynos | don't think I need to do this ...
  #return if (ideal_dynos - current_dynos).abs < options[:step]

  #this turns 32 into 30
  stepped_dynos = (ideal_dynos/options[:step]).round * options[:step]

  #this turns 30 into 35
  stepped_dynos += options[:step]

  #this makes sure that it stays within the min max bounds
  stepped_dynos = options[:min_dynos] if stepped_dynos < options[:min_dynos]
  stepped_dynos = options[:max_dynos] if stepped_dynos > options[:max_dynos]

  # Don't allow downscaling until 5 minutes
  if stepped_dynos < current_dynos && (Time.now - last_scaled) < (60 * 60) # 1 hour
    #puts ">> Current: [#{current_dynos}], Ideal: [#{stepped_dynos}] | will not downscale within an hour"
    nil
  elsif stepped_dynos != current_dynos
    set_dynos(stepped_dynos)
    stepped_dynos
  else
    nil
  end

end

#set_dynos(count) ⇒ Object 



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# File 'lib/heroku_mongo_watcher/autoscaler.rb', line 76

def set_dynos(count)
  @last_scaled = Time.now
  t = Thread.new('Setting Dynos') do
    i = heroku.ps_scale(config[:heroku_appname], :type => 'web', :qty => count)
  end
  t.join

end