Firstly install Sidekiq gem in your project:

gem 'sidekiq'

Once that's done, create a worker in app/workers/worker_name.rb:

class ImportOrders
  include Sidekiq::Worker
  require 'csv'

  def perform(csv_file)
    CSV.foreach(Rails.root.join(csv_file), headers: true) do |row|
      p row
    end
  end
end

You will need to have redis in your system:

brew install redis

Then to start Sidekiq locally:

bundle exec sidekiq