Sidekiq Initializer

database.rb

module Platform
  module Database
    def connect(size=35)
      config = ActiveRecord::Base.configurations[Rails.env]
      config['pool'] = ENV['DB_POOL'] || size
      ActiveRecord::Base.establish_connection(config)
    end

    def disconnect
      ActiveRecord::Base.connection_pool.disconnect!
    end

    def reconnect(size)
      disconnect
      connect(size)
    end

    module_function :disconnect, :connect, :reconnect
  end
end

sidekiq.rb

Rails.application.config.after_initialize do
  ActiveSupport.on_load(:active_record) do
    Sidekiq.configure_server do |config|
      size = Sidekiq.options[:concurrency]
      Platform::Database.reconnect(size)
      config.server_middleware do |chain|
        chain.add Sidekiq::Middleware::Server::Rescue
      end
    end
  end
end