Add okcomputer check sidekiq retry queue

[elrayle]

Adapt from...

class SidekiqRetryQueueCheck < OkComputer::Check
  def check
    if sidekiq_retry_size > sidekiq_retry_size_threshold
      mark_failure
      mark_message "Sidekiq retry queue size (#{sidekiq_retry_size}) is above the threshold (#{sidekiq_retry_size_threshold})"
    else
      mark_message "Sidekiq retry queue size (#{sidekiq_retry_size}) is below the threshold (#{sidekiq_retry_size_threshold})"
    end
  rescue => e
    mark_failure
    mark_message "Unable to check sidekiq retry queue size with error: #{e}"
  end

  private

  def sidekiq_retry_size
    Sidekiq::Stats.new.retry_size.to_i
  end

  def sidekiq_retry_size_threshold
    Settings.sidekiq_retry_queue_threshold.to_i
  end
end

OkComputer::Registry.register 'sidekiq-retry', SidekiqRetryQueueCheck.new

[JesiBuell79]

Not sure what this is or if we need - will leave for you to judge --

[chrisrlc]

Relevant docs:

• https://github.com/sidekiq/sidekiq/wiki/API
• https://github.com/sportngin/okcomputer
• https://github.com/sportngin/okcomputer/blob/master/lib/ok_computer/built_in_checks/sidekiq_latency_check.rb