Add ability to set all fieldnames to lowercase

描述

Since there's no way to make searching on field names case insensitive, a filter/feature to set all fieldnames to lowercase would be helpful. For example, if you have two different log sources and one uses "hostname" as a field name and the other uses "Hostname" as a field. By setting all fieldnames to lower case, it would allow joining of log source searches.

貢獻者指南

技術棧

ruby

領域

data

議題類型

feature

難度面向新貢獻者的預計實作難度，1 表示很小改動，5 表示專家級工作。

3

預計時間有經驗貢獻者完成調查、實作、測試並準備 pull request 的粗略時間範圍。

1-2 days

活動狀態議題目前的可參與程度：新鮮、活躍、陳舊、阻塞或等待維護者輸入。

stale

清晰度議題是否清楚說明預期改動、驗收標準和下一步。

clear

前置要求

Basic understanding of Logstash pipeline and filter plugins

新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。

60

研究方向

Review the existing mutate filter in Logstash (lib/logstash/filters/mutate.rb) to understand how field transformations are implemented. Check the issue comments for any design discussions or proposed solutions. Then, implement a new filter option or extend mutate to lowercase all field names, ensuring configuration compatibility with existing pipelines.