DynoScaler

Scale your dyno workers on Heroku as needed, pay only for what you use!

Installation

Add this line to your application's Gemfile:

gem 'dyno_scaler'

And then execute:

$ bundle

Or install it yourself as:

$ gem install dyno_scaler

Usage

Just include this module in your Resque job and you're good to go:

class MyJob
  include DynoScaler::Workers::Resque

  ...
end

You can access the configuration with (for example):

DynoScaler.configuration.max_workers = 3

In Rails, you can access it easily in your application.rb:

config.dyno_scaler.max_workers = 3

If you want to scale up or down your workers manually, you can use the manager directly:

DynoScaler.manager.scale_up(options)
DynoScaler.manager.scale_down(options)

You must pass an options hash with the number of workers, the number of pending jobs, and the number of running jobs, like so:

{
  workers: 10,
  working: 3,
  pending: 5
}

Resque.info returns a hash with these keys, so you may just pass it instead:

DynoScaler.manager.scale_up(Resque.info)

You can also use the DynoScaler::Manager#scale_with method, passing the Resque.info:

DynoScaler.manager.scale_with(Resque.info)

It will check whether to scale up or down based on the number of workers running, pending jobs, and working jobs.

Heroku Deploy

When deploying to heroku you'll want to add these two configuration keys:

HEROKU_API_KEY=<YOUR-API-KEY-HERE>
HEROKU_APP=<THE-NAME-OF-YOUR-APP-ON-HEROKU-HERE>

They are used by the heroku-api gem to scale dynos of your application.

Async

Whenever DynoScaler needs to scale workers up it will perform a request to the Heroku API. This request may sometimes take longer to return than one would want. Because of this we have a async option that uses GirlFriday to handle this call asynchronously. To enable it, just set it to true:

config.dyno_scaler.async = true

You can also give it a block to better customize it. It will receive an options hash that can be passed to the DynoScaler::Manager#scale_with method, like so:

MY_QUEUE = GirlFriday::WorkQueue.new(:my_queue, size: 5) do |options|
  DynoScaler.manager.scale_with(options)
end

config.dyno_scaler.async do |options|
  MY_QUEUE << options
end

Contributing

Fork it
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request