gistfile1.txt

<match ...>
  type metrics

  key ...

  tag metrics.mongo

</match>

<match metrics.mongo>
  type mongo_incr
  host
  port
  collection
</match>

class MongoIncrOutput < MongoOutput
  def format
  end

  def write(chunk)
    chunk.each {|key,val|
       @collection.incr(key, value)
    }
  end
end