Embedding rufus scheduler within sidekiq. Put this file into your rails `config/initializers` folder.

rufus.rb

require 'rufus/scheduler'
require 'redis'
require 'redis-lock'

if $0 == 'sidekiq'
  $redis = Redis.new

  def run_rake task
    $redis.lock_for_update(task, 100, 0) do
      puts "scheduling #{task}"
      Rake::Task[task].reenable
      Rake::Task[task].invoke
    end
  rescue => e
    puts e.message
  end

  scheduler = Rufus::Scheduler.start_new

  scheduler.cron '0 8 * * *' do
    run_rake "schedule:daily_mailer"
  end

  scheduler.cron '0 0 * * *' do
    run_rake "schedule:midnight_job"
  end
  
  scheduler.cron '0 8 * * 6' do
    run_rake "schedule:weekly_job"
  end
end

Updated the gist to use rufus scheduler. Cleans things up a ton and has better support for cron-like scheduling.