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.

贡献者指南

技术栈

ruby

领域

data

议题类型

feature

难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。

3

预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。

1-2 days

活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。

stale

清晰度议题是否清楚说明期望改动、验收标准和下一步。

clear

前置要求

Basic understanding of Logstash pipeline and filter plugins

新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。

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.