Adding support for histograms

micrometer-core/src/main/java/io/micronaut/configuration/metrics/binder/web/HttpHistogramMeterFilterFactory.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2017-2024 original authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.micronaut.configuration.metrics.binder.web;
+
+import io.micrometer.core.instrument.Meter;
+import io.micrometer.core.instrument.config.MeterFilter;
+import io.micrometer.core.instrument.distribution.DistributionStatisticConfig;
+import io.micronaut.configuration.metrics.annotation.RequiresMetrics;
+import io.micronaut.context.annotation.*;
+import jakarta.inject.Singleton;
+
+import static io.micronaut.configuration.metrics.micrometer.MeterRegistryFactory.MICRONAUT_METRICS_BINDERS;
+import static io.micronaut.core.util.StringUtils.FALSE;
+
+/**
+ * Optional filter for adding histograms to HTTP metrics.
+ *
+ * @author lcavadas
+ */
+@Factory
+@RequiresMetrics
+@Requires(property = WebMetricsPublisher.ENABLED, notEquals = FALSE)
+@Primary
+public class HttpHistogramMeterFilterFactory {
+
+  /**
+   * Configure new MeterFilter for http.server.requests metrics.
+   *
+   * @param histogram If a histogram should be published
+   * @return A MeterFilter
+   */
+  @Bean
+  @Singleton
+  @Requires(property = MICRONAUT_METRICS_BINDERS + ".web.server.histogram")
+  MeterFilter addServerPercentileMeterFilter(@Value("${" + MICRONAUT_METRICS_BINDERS + ".web.server.histogram}") Boolean histogram) {
+    return getMeterFilter(histogram, WebMetricsPublisher.METRIC_HTTP_SERVER_REQUESTS);
+  }
+
+  /**
+   * Configure new MeterFilter for http.client.requests metrics.
+   *
+   * @param histogram If a histogram should be published
+   * @return A MeterFilter
+   */
+  @Bean
+  @Singleton
+  @Requires(property =  MICRONAUT_METRICS_BINDERS + ".web.client.histogram")
+  MeterFilter addClientPercentileMeterFilter(@Value("${" + MICRONAUT_METRICS_BINDERS + ".web.client.histogram}") Boolean histogram) {
+    return getMeterFilter(histogram, WebMetricsPublisher.METRIC_HTTP_CLIENT_REQUESTS);
+  }
+
+  private MeterFilter getMeterFilter(Boolean histogram, String metricNamePrefix) {
+    return new MeterFilter() {
+      @Override
+      public DistributionStatisticConfig configure(Meter.Id id, DistributionStatisticConfig config) {
+        if (id.getName().startsWith(metricNamePrefix)) {
+          return DistributionStatisticConfig.builder()
+            .percentilesHistogram(histogram)
+            .build()
+            .merge(config);
+        }
+        return config;
+      }
+    };
+  }
+}

micrometer-core/src/test/groovy/io/micronaut/configuration/metrics/binder/web/HttpMetricsSpec.groovy

@@ -55,6 +55,8 @@ class HttpMetricsSpec extends Specification {
         clientTimer.count() == 1
         serverSnapshot.percentileValues().length == serverPercentilesCount
         clientSnapshot.percentileValues().length == clientPercentilesCount
+        serverTimer.getMetaPropertyValues().find { it.name.equals('distributionStatisticConfig') }.value.percentileHistogram == serverHistogram
+        clientTimer.getMetaPropertyValues().find { it.name.equals('distributionStatisticConfig') }.value.percentileHistogram == clientHistogram
 
         when: "A request is sent to the root route"
 
@@ -135,9 +137,13 @@ class HttpMetricsSpec extends Specification {
         embeddedServer.close()
 
         where:
-        cfg                                                   | setting     | serverPercentilesCount | clientPercentilesCount
-        MICRONAUT_METRICS_BINDERS + ".web.client.percentiles" | "0.95,0.99" | 0                      | 2
-        MICRONAUT_METRICS_BINDERS + ".web.server.percentiles" | "0.95,0.99" | 2                      | 0
+        cfg                                                   | setting     | serverPercentilesCount | clientPercentilesCount| serverHistogram | clientHistogram
+        MICRONAUT_METRICS_BINDERS + ".web.client.percentiles" | "0.95,0.99" | 0                      | 2                     | null            | null
+        MICRONAUT_METRICS_BINDERS + ".web.server.percentiles" | "0.95,0.99" | 2                      | 0                     | null            | null
+        MICRONAUT_METRICS_BINDERS + ".web.server.histogram"   | "true"      | 0                      | 0                     | true            | null
+        MICRONAUT_METRICS_BINDERS + ".web.server.histogram"   | "false"     | 0                      | 0                     | false           | null
+        MICRONAUT_METRICS_BINDERS + ".web.client.histogram"   | "true"      | 0                      | 0                     | null            | true
+        MICRONAUT_METRICS_BINDERS + ".web.client.histogram"   | "false"     | 0                      | 0                     | null            | false
     }
 
     void "test client / server metrics ignored uris for client errors"() {