out_autotypecast.rb

#
# Auto typecast
# =============
#
# Ref:: http://y-ken.hatenablog.com/entry/fluentd-parser-auto-type-conversion
#
# ちなみにこの方法だとApacheとかNginxのログで、"-"とかが流れたときにIntegerとStringが混ざって死ぬ。
#

module Fluent
  class AutoTypecastOutput < Output
    Fluent::Plugin.register_output('auto_typecast', self)

    config_param :add_prefix, :string, default: 'typed'

    def emit(tag, es, chain)
      if @add_prefix
        tag = "#{@add_prefix}.#{tag}"
      end

      es.each do |time, record|
        record.keys.each do |key|
          record[key] = typecast(key, record[key])
        end
        Fluent::Engine.emit(tag, time, record)
      end
      chain.next
    end

    def typecast(key, value)
      if value == value.to_i.to_s
        value = value.to_i
      elsif value == value.to_f.to_s
        value = value.to_f
      end
      value
    end
  end
end