prometheus/prometheus

Set and check (and document) a global label_value_length_limit

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#16,525 建立於 2025年4月30日

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 (16 留言) (0 反應) (1 負責人)Go (64,042 star) (10,408 fork)batch import
component/documentationcomponent/scrapinggood first issuehelp wantedkind/featurepriority/P3

描述

Proposal

Prometheus has label_name_length_limit and label_value_length_limit, currently defaulted to no limit.

After #16069, Prometheus will crash if you give it a name or value longer than 16MB, so we should at least have a default limit lower than that.

I think that a reasonable limit would be more like 200 bytes, but I am aware of people doing exciting things like storing a bitmap in a label. Maybe we could go with something like 1MB?

The code checking limits while scraping would need to check before constructing the Labels data structure, and we should check in other places such as the remote-write receiver, label_replace, label_join.

貢獻者指南

技術棧
go
領域
observabilitybackend
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。
active
清晰度議題是否清楚說明預期改動、驗收標準和下一步。
mostly clear
前置要求
Go programmingPrometheus internalsLabel handling
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。
25
研究方向
Review the existing label name length limit and label value length limit configuration options. Identify where label values are constructed during scraping and remote write handling. Consider the impact on label replace and label join. The assignee has been working on this; check their comments for specific file suggestions.