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

If you are using Sidekiq, then just configure the middlewares:

# Client middleware
Sidekiq.configure_client do |config|
  config.client_middleware do |chain|
    chain.add DynoScaler::Workers::Sidekiq::ClientMiddleware
  end
end

# Server middleware
Sidekiq.configure_server do |config|
  # Configure client middleware here if your jobs may enqueue another jobs
  config.client_middleware do |chain|
    chain.add DynoScaler::Workers::Sidekiq::ClientMiddleware
  end

  config.server_middleware do |chain|
    chain.add DynoScaler::Workers::Sidekiq::ServerMiddleware
  end
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.

For Sidekiq you can use DynoScaler::Workers::Sidekiq.info method instead of Resque.info.

Heroku Deploy

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

HEROKU_OAUTH_TOKEN=<YOUR-OAUTH-TOKEN-HERE>
HEROKU_APP=<THE-NAME-OF-YOUR-APP-ON-HEROKU-HERE>

They are used by the platform-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

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