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Time-windowed max gauge for OTLP histograms #6159

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Time-windowed max gauge for OTLP histograms #6159

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1f0ec01
Support max in OTLP histogram
BenEfrati Dec 25, 2024
4562a34
add timeunit only for time based meter
BenEfrati Dec 26, 2024
d42ef85
remove time unit from metric name
BenEfrati Apr 23, 2025
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16 changes: 16 additions & 0 deletions ...crometer-registry-otlp/src/main/java/io/micrometer/registry/otlp/OtlpMetricConverter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -126,6 +126,8 @@ private void writeHistogramSupport(HistogramSupport histogramSupport) {
double max = isTimeBased ? histogramSnapshot.max(baseTimeUnit) : histogramSnapshot.max();
long count = histogramSnapshot.count();

addMaxGaugeForTimer(id, tags, max);
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@jonatan-ivanov jonatan-ivanov Oct 9, 2025

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addMaxGaugeForHistogramSupport?
Since this is for both Timer and DistributionSummary.


// if percentiles configured, use summary
if (histogramSnapshot.percentileValues().length != 0) {
buildSummaryDataPoint(histogramSupport, tags, startTimeNanos, total, count, isTimeBased, histogramSnapshot);
Expand Down Expand Up @@ -154,6 +156,20 @@ private static Optional<ExponentialHistogramSnapShot> getExponentialHistogramSna
return Optional.empty();
}

private void addMaxGaugeForTimer(Meter.Id id, Iterable<KeyValue> tags, double max) {
String metricName = id.getName() + ".max";
Metric.Builder metricBuilder = getOrCreateMetricBuilder(id.withName(metricName), DataCase.GAUGE);
if (!metricBuilder.hasGauge()) {
metricBuilder.setGauge(io.opentelemetry.proto.metrics.v1.Gauge.newBuilder());
}

metricBuilder.getGaugeBuilder()
.addDataPoints(NumberDataPoint.newBuilder()
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@jonatan-ivanov jonatan-ivanov Oct 9, 2025

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It seems addDataPoints has an overload for NumberDataPointBuilder and NumberDataPoint too?
It seems writeGauge (which is quite similar to this) uses NumberDataPoint (calls .build()) while this one does not. Should not be the two consistent?

.setTimeUnixNano(TimeUnit.MILLISECONDS.toNanos(clock.wallTime()))
.setAsDouble(max)
.addAllAttributes(tags));
}

private void writeFunctionTimer(FunctionTimer functionTimer) {
Metric.Builder builder = getOrCreateMetricBuilder(functionTimer.getId(), DataCase.HISTOGRAM);
HistogramDataPoint.Builder histogramDataPoint = HistogramDataPoint.newBuilder()
Expand Down
2 changes: 2 additions & 0 deletions ...registry-otlp/src/test/java/io/micrometer/registry/otlp/OTelCollectorIntegrationTest.java
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Expand Up @@ -107,11 +107,13 @@ void collectorShouldExportMetrics() throws Exception {
// see: https://github.com/open-telemetry/opentelemetry-collector-contrib/pull/20519
matchesPattern("(?s)^.*test_timer_milliseconds_sum\\{.+} 123\\.0\\n.*$"),
matchesPattern("(?s)^.*test_timer_milliseconds_bucket\\{.+,le=\"\\+Inf\"} 1\\n.*$"),
matchesPattern("(?s)^.*test_timer_max_milliseconds\\{.+} 123\\.0\n.*$"),
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@jonatan-ivanov jonatan-ivanov Oct 9, 2025

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Since this is a separate gauge, there should be two more lines, something like this should cover them:

containsString("# HELP test_timer_max_milliseconds \n"),
containsString("# TYPE test_timer_max_milliseconds gauge\n"),


containsString("# HELP test_ds \n"),
containsString("# TYPE test_ds histogram\n"),
matchesPattern("(?s)^.*test_ds_count\\{.+} 1\\n.*$"),
matchesPattern("(?s)^.*test_ds_sum\\{.+} 24\\.0\\n.*$"),
matchesPattern("(?s)^.*test_ds_max\\{.+} 24\\.0\\n.*$"),
matchesPattern("(?s)^.*test_ds_bucket\\{.+,le=\"\\+Inf\"} 1\\n.*$")
);
// @formatter:on
Expand Down
77 changes: 46 additions & 31 deletions ...istry-otlp/src/test/java/io/micrometer/registry/otlp/OtlpCumulativeMeterRegistryTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@
import java.lang.management.ManagementFactory;
import java.lang.management.OperatingSystemMXBean;
import java.time.Duration;
import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

Expand Down Expand Up @@ -111,7 +112,9 @@ void timer() {
timer.record(111, TimeUnit.MILLISECONDS);
clock.add(otlpConfig().step());
timer.record(4, TimeUnit.MILLISECONDS);
assertThat(writeToMetric(timer).toString()).isEqualTo(
List<Metric> metrics = writeToMetrics(timer);
Metric metric = metrics.stream().filter(Metric::hasHistogram).findFirst().orElseThrow();
assertThat(metric.toString()).isEqualTo(
"name: \"web.requests\"\n" + "description: \"timing web requests\"\n" + "unit: \"milliseconds\"\n"
+ "histogram {\n" + " data_points {\n" + " start_time_unix_nano: 1000000\n"
+ " time_unix_nano: 60001000000\n" + " count: 4\n" + " sum: 202.0\n" + " }\n"
Expand All @@ -128,7 +131,9 @@ void timerWithHistogram() {
clock.add(otlpConfig().step());
timer.record(4, TimeUnit.MILLISECONDS);

assertThat(writeToMetric(timer).toString())
List<Metric> metrics = writeToMetrics(timer);
Metric metric = metrics.stream().filter(Metric::hasHistogram).findFirst().orElseThrow();
assertThat(metric.toString())
.isEqualTo("name: \"http.client.requests\"\n" + "unit: \"milliseconds\"\n" + "histogram {\n"
+ " data_points {\n" + " start_time_unix_nano: 1000000\n" + " time_unix_nano: 60001000000\n"
+ " count: 5\n" + " sum: 60202.0\n" + " bucket_counts: 0\n" + " bucket_counts: 0\n"
Expand Down Expand Up @@ -198,13 +203,14 @@ void timerWithPercentiles() {
timer.record(77, TimeUnit.MILLISECONDS);
timer.record(111, TimeUnit.MILLISECONDS);

assertThat(writeToMetric(timer).toString())
.isEqualTo("name: \"service.requests\"\n" + "unit: \"milliseconds\"\n" + "summary {\n" + " data_points {\n"
+ " start_time_unix_nano: 1000000\n" + " time_unix_nano: 1000000\n" + " count: 3\n"
+ " sum: 198.0\n" + " quantile_values {\n" + " quantile: 0.5\n"
+ " value: 79.167488\n" + " }\n" + " quantile_values {\n" + " quantile: 0.9\n"
+ " value: 112.72192\n" + " }\n" + " quantile_values {\n" + " quantile: 0.99\n"
+ " value: 112.72192\n" + " }\n" + " }\n" + "}\n");
List<Metric> metrics = writeToMetrics(timer);
Metric metric = metrics.stream().filter(Metric::hasSummary).findFirst().orElseThrow();
assertThat(metric.toString()).isEqualTo("name: \"service.requests\"\n" + "unit: \"milliseconds\"\n"
+ "summary {\n" + " data_points {\n" + " start_time_unix_nano: 1000000\n"
+ " time_unix_nano: 1000000\n" + " count: 3\n" + " sum: 198.0\n" + " quantile_values {\n"
+ " quantile: 0.5\n" + " value: 79.167488\n" + " }\n" + " quantile_values {\n"
+ " quantile: 0.9\n" + " value: 112.72192\n" + " }\n" + " quantile_values {\n"
+ " quantile: 0.99\n" + " value: 112.72192\n" + " }\n" + " }\n" + "}\n");
}

@Test
Expand All @@ -230,10 +236,11 @@ void distributionSummary() {
size.record(2233);
clock.add(otlpConfig().step());
size.record(204);

assertThat(writeToMetric(size).toString()).isEqualTo("name: \"http.response.size\"\n" + "unit: \"bytes\"\n"
+ "histogram {\n" + " data_points {\n" + " start_time_unix_nano: 1000000\n"
+ " time_unix_nano: 60001000000\n" + " count: 4\n" + " sum: 2552.0\n" + " }\n"
List<Metric> metrics = writeToMetrics(size);
Metric metric = metrics.stream().filter(Metric::hasHistogram).findFirst().orElseThrow();
assertThat(metric.toString()).isEqualTo("name: \"http.response.size\"\n" + "unit: \"bytes\"\n" + "histogram {\n"
+ " data_points {\n" + " start_time_unix_nano: 1000000\n" + " time_unix_nano: 60001000000\n"
+ " count: 4\n" + " sum: 2552.0\n" + " }\n"
+ " aggregation_temporality: AGGREGATION_TEMPORALITY_CUMULATIVE\n" + "}\n");
}

Expand Down Expand Up @@ -471,7 +478,7 @@ void distributionSummaryWithHistogram() {
+ " explicit_bounds: 3.8430716820228234E18\n" + " explicit_bounds: 4.2273788502251054E18\n"
+ " }\n" + " aggregation_temporality: AGGREGATION_TEMPORALITY_CUMULATIVE\n" + "}\n";
String[] expectedLines = expected.split("\n");
String actual = writeToMetric(size).toString();
String actual = writeToMetrics(size).stream().filter(Metric::hasHistogram).findFirst().orElseThrow().toString();
String[] actualLines = actual.split("\n");
assertThat(actualLines).hasSameSizeAs(expectedLines);
for (int i = 0; i < actualLines.length; i++) {
Expand Down Expand Up @@ -505,13 +512,14 @@ void distributionSummaryWithPercentiles() {
clock.add(otlpConfig().step());
size.record(204);

assertThat(writeToMetric(size).toString())
.isEqualTo("name: \"http.response.size\"\n" + "unit: \"bytes\"\n" + "summary {\n" + " data_points {\n"
+ " start_time_unix_nano: 1000000\n" + " time_unix_nano: 60001000000\n" + " count: 4\n"
+ " sum: 2552.0\n" + " quantile_values {\n" + " quantile: 0.5\n" + " value: 200.0\n"
+ " }\n" + " quantile_values {\n" + " quantile: 0.9\n" + " value: 200.0\n"
+ " }\n" + " quantile_values {\n" + " quantile: 0.99\n" + " value: 200.0\n"
+ " }\n" + " }\n" + "}\n");
List<Metric> metrics = writeToMetrics(size);
Metric metric = metrics.stream().filter(Metric::hasSummary).findFirst().orElseThrow();
assertThat(metric.toString()).isEqualTo("name: \"http.response.size\"\n" + "unit: \"bytes\"\n" + "summary {\n"
+ " data_points {\n" + " start_time_unix_nano: 1000000\n" + " time_unix_nano: 60001000000\n"
+ " count: 4\n" + " sum: 2552.0\n" + " quantile_values {\n" + " quantile: 0.5\n"
+ " value: 200.0\n" + " }\n" + " quantile_values {\n" + " quantile: 0.9\n"
+ " value: 200.0\n" + " }\n" + " quantile_values {\n" + " quantile: 0.99\n"
+ " value: 200.0\n" + " }\n" + " }\n" + "}\n");
}

private double extractValue(String line) {
Expand All @@ -525,19 +533,22 @@ void longTaskTimer() {
LongTaskTimer.Sample task2 = taskTimer.start();
this.clock.add(otlpConfig().step().multipliedBy(3));

assertThat(writeToMetric(taskTimer).toString())
.isEqualTo("name: \"checkout.batch\"\n" + "unit: \"milliseconds\"\n" + "histogram {\n" + " data_points {\n"
+ " start_time_unix_nano: 1000000\n" + " time_unix_nano: 180001000000\n" + " count: 2\n"
+ " sum: 360000.0\n" + " }\n"
+ " aggregation_temporality: AGGREGATION_TEMPORALITY_CUMULATIVE\n" + "}\n");
List<Metric> metrics = writeToMetrics(taskTimer);
Metric metric = metrics.stream().filter(Metric::hasHistogram).findFirst().orElseThrow();
assertThat(metric.toString()).isEqualTo("name: \"checkout.batch\"\n" + "unit: \"milliseconds\"\n"
+ "histogram {\n" + " data_points {\n" + " start_time_unix_nano: 1000000\n"
+ " time_unix_nano: 180001000000\n" + " count: 2\n" + " sum: 360000.0\n" + " }\n"
+ " aggregation_temporality: AGGREGATION_TEMPORALITY_CUMULATIVE\n" + "}\n");

task1.stop();
task2.stop();
this.clock.add(otlpConfig().step());

// this is not right that count/sum reset, but it's the same thing we do with
// prometheus
assertThat(writeToMetric(taskTimer).toString())
metrics = writeToMetrics(taskTimer);
metric = metrics.stream().filter(Metric::hasHistogram).findFirst().orElseThrow();
assertThat(metric.toString())
.isEqualTo("name: \"checkout.batch\"\n" + "unit: \"milliseconds\"\n" + "histogram {\n" + " data_points {\n"
+ " start_time_unix_nano: 1000000\n" + " time_unix_nano: 240001000000\n" + " sum: 0.0\n"
+ " }\n" + " aggregation_temporality: AGGREGATION_TEMPORALITY_CUMULATIVE\n" + "}\n");
Expand Down Expand Up @@ -568,7 +579,8 @@ void testExponentialHistogramWithTimer() {
timer.record(Duration.ofMillis(100));
timer.record(Duration.ofMillis(1000));

Metric metric = writeToMetric(timer);
List<Metric> metrics = writeToMetrics(timer);
Metric metric = metrics.stream().filter(Metric::hasExponentialHistogram).findFirst().orElseThrow();
assertThat(metric.getExponentialHistogram().getDataPointsCount()).isPositive();

ExponentialHistogramDataPoint exponentialHistogramDataPoint = metric.getExponentialHistogram().getDataPoints(0);
Expand All @@ -585,7 +597,8 @@ void testExponentialHistogramWithTimer() {
clock.add(exponentialHistogramOtlpConfig().step());
timer.record(Duration.ofMillis(10000));

metric = writeToMetric(timer);
metrics = writeToMetrics(timer);
metric = metrics.stream().filter(Metric::hasExponentialHistogram).findFirst().orElseThrow();
exponentialHistogramDataPoint = metric.getExponentialHistogram().getDataPoints(0);
assertThat(exponentialHistogramDataPoint.getTimeUnixNano() - previousEndTime)
.isEqualTo(otlpConfig().step().toNanos());
Expand All @@ -611,7 +624,8 @@ void testExponentialHistogramDs() {
ds.record(100);
ds.record(1000);

Metric metric = writeToMetric(ds);
List<Metric> metrics = writeToMetrics(ds);
Metric metric = metrics.stream().filter(Metric::hasExponentialHistogram).findFirst().orElseThrow();
assertThat(metric.getExponentialHistogram().getDataPointsCount()).isPositive();

ExponentialHistogramDataPoint exponentialHistogramDataPoint = metric.getExponentialHistogram().getDataPoints(0);
Expand All @@ -628,7 +642,8 @@ void testExponentialHistogramDs() {
clock.add(exponentialHistogramOtlpConfig().step());
ds.record(10000);

metric = writeToMetric(ds);
metrics = writeToMetrics(ds);
metric = metrics.stream().filter(Metric::hasExponentialHistogram).findFirst().orElseThrow();
exponentialHistogramDataPoint = metric.getExponentialHistogram().getDataPoints(0);
assertThat(exponentialHistogramDataPoint.getTimeUnixNano() - previousEndTime)
.isEqualTo(otlpConfig().step().toNanos());
Expand Down
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