background_indexer.rb

module BackgroundIndexer
  extend ActiveSupport::Concern

  included do
    after_save    { IndexerJob.perform_later('index', self.class.index_name, self.class.name.downcase, self) }
    after_destroy { IndexerJob.perform_later('delete', self.class.index_name, self.class.name.downcase, self.id) }
  end
end

indexer_job.rb

class IndexerJob < ActiveJob::Base
  Logger = Sidekiq.logger.level == Logger::DEBUG ? Sidekiq.logger : nil
  Client = Elasticsearch::Client.new logger: Logger

  def perform(operation, index_name, type, record)
    case operation.to_s
      when 'index'
        Client.index(index: index_name,
                     type: type,
                     id: record.id,
                     body: record.__elasticsearch__.as_indexed_json)
      when 'delete'
        Client.delete(index: index_name, type: type, id: record)
      else raise ArgumentError, "Unknown operation '#{operation}'"
    end
  end
end

searchable.rb

module Searchable
  extend ActiveSupport::Concern
  included do
    include Elasticsearch::Model
    include BackgroundIndexer
    index_name "#{Rails.env}-#{self.name.downcase.pluralize}"
  end
end