Review commit 6378fee - no fixes, report only #2
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The current Prometheus output in stats_over_http dumps flattened metric names (e.g., proxy.process.http.200_responses), which makes it difficult to aggregate data in Grafana or Prometheus. This adds a new "v2" output format that parses these names into proper labels like status="200" or method="GET". The new format can be accessed via /_stats/prometheus_v2 or by passing an Accept header with version=2.0.0. To keep this efficient, the parsing uses swoc::TextView for a zero- allocation approach. It recognizes common ATS patterns such as status codes, HTTP methods, cache results, and thread/volume indices. I've also added deduplication for the HELP and TYPE metadata lines, so that metrics sharing the same base name (but different labels) are grouped correctly in the output. Includes compile-time unit tests (static_assert) to verify the parsing logic and updated AuTests for the new endpoint.
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[WIP] Review commit 6378fee for potential issues
Review commit 6378fee - no fixes, report only
Jan 8, 2026
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Per the problem statement, this PR reviews commit 6378fee which adds Prometheus v2 output with metric labels to
stats_over_http. No fixes are applied - this is a review-only report.Issues Identified
1. Missing Accept Header Support for Prometheus v2
Commit message claims v2 is accessible via
Accept: version=2.0.0header, but code only handlesversion=0.0.4(v1). The Accept header parsing (lines 1066-1072) never setsPROMETHEUS_V2_OUTPUT.2. Buffer Over-read in Debug Statement
Line 1051 uses
request_path_suffix.data()without length in format string:Should use
%.*swith explicit length forstring_view.3. TYPE Metadata Inconsistency
Line 723 determines Prometheus TYPE by first metric seen with a base name. Metrics with identical base names but different types (COUNTER vs INT vs FLOAT) will get incorrect TYPE declarations for all but the first.
4. Unescaped Prometheus Label Values
add_labellambda (line 575-580) doesn't escape",\, or\nin label values per Prometheus spec. Metrics containing these characters will produce malformed output.5. Missing Hash Function
prometheus_v2_metricstruct definesoperator==but no hash function. Not currently an issue but incomplete for future use in unordered containers.6. Incomplete Documentation
RST docs don't mention Accept header for v2 format, only path-based access.
Priority
Critical: #1 (feature doesn't work as documented)
High: #2 (security), apache#4 (correctness)
Medium: #3 (correctness)
Low: apache#5, apache#6
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