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fix(config): keep metric name case in metric-specific properties - #2588
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zeitlinger merged 1 commit intoOct 23, 2026
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normalizePropertyKey() lowercases the whole key, so settings for a metric with uppercase letters, such as io.prometheus.metrics.myLatency.histogram_classic_upper_bounds, are stored under my_latency and never found for myLatency. Normalize only the property name in io.prometheus.metrics.<metric>.<property> keys, so metric names keep their case as they did before 1.5.0. Signed-off-by: Tanishq Choudhary <tanishqchoudhary007@gmail.com>
Tanishq-Choudhary
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fstab,
jaydeluca and
zeitlinger
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October 22, 2026 15:40
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Problem
Since 1.5.0, metric-specific properties are ignored when the metric name has an uppercase letter. With
io.prometheus.metrics.myLatency.histogram_classic_upper_bounds=.005, .01, .015a histogram named
myLatencykeeps the default buckets.normalizePropertyKey(), added in #1828 to accept camelCase property names, lowercases the whole key including the metric name. The settings are stored undermy_latency, whileStatefulMetriclooks them up asmyLatencyand getsnull. There is no "Unknown property" error because the key was consumed. In 1.4.3 the same config (withhistogramClassicUpperBounds) applies tomyLatency; I ran both versions to check. An automated review comment on #1828 pointed this out, but metric names are still lowercased on main.Fix
In
io.prometheus.metrics.<metric>.<property>keys only the property name is normalized, soio.prometheus.metrics.myLatency.histogramNativeOnlybecomesio.prometheus.metrics.myLatency.histogram_native_only. Default metric keys and exporter keys are normalized as before, and environment variables are not affected.A key written with uppercase letters for a lowercase metric, like
io.prometheus.metrics.My_metric.histogram_native_onlyformy_metric, no longer applies. That matches 1.4.x.How tested
New
PrometheusPropertiesLoaderTest.metricSpecificPropertiesShouldKeepMetricNameCasefails on main with aNullPointerExceptionbecausegetMetricProperties("myLatency")returnsnull, and passes with this change. I also added a case tonormalizePropertyKeyShouldConvertCamelCaseToSnakeCase.prometheus-metrics-config(62 tests, coverage check) andprometheus-metrics-core(178 tests) pass on JDK 25. google-java-format 1.37.0 and checkstyle are clean on the changed files. I did not runmise run lintor the exporter modules.@zeitlinger this changes the key normalization from #1828.