notify_by Twitter do |tweet|
  tweet.on_success = true
  tweet.on_warning = true
  tweet.on_failure = true

  tweet.consumer_key       = 'my_consumer_key'
  tweet.consumer_secret    = 'my_consumer_secret'
  tweet.oauth_token        = 'my_oauth_token'
  tweet.oauth_token_secret = 'my_oauth_token_secret'

In order to use Twitter as a notifier you will need a Twitter account. Once you create a Twitter account for the notifier, you need to register a new application for your Twitter account. After registering an application you will acquire the following credentials:

You can find these credentials on your application’s pages.