JSON exporter for Micrometer

extensions/micrometer/deployment/src/main/java/io/quarkus/micrometer/deployment/export/JsonRegistryProcessor.java

@@ -0,0 +1,53 @@
+package io.quarkus.micrometer.deployment.export;
+
+import java.util.function.BooleanSupplier;
+
+import org.jboss.logging.Logger;
+
+import io.quarkus.arc.deployment.AdditionalBeanBuildItem;
+import io.quarkus.deployment.annotations.BuildProducer;
+import io.quarkus.deployment.annotations.BuildStep;
+import io.quarkus.deployment.annotations.ExecutionTime;
+import io.quarkus.deployment.annotations.Record;
+import io.quarkus.deployment.builditem.nativeimage.ReflectiveClassBuildItem;
+import io.quarkus.micrometer.deployment.MicrometerRegistryProviderBuildItem;
+import io.quarkus.micrometer.runtime.config.MicrometerConfig;
+import io.quarkus.micrometer.runtime.export.JsonMeterRegistryProvider;
+import io.quarkus.micrometer.runtime.export.JsonRecorder;
+import io.quarkus.micrometer.runtime.registry.json.JsonMeterRegistry;
+import io.quarkus.vertx.http.deployment.RouteBuildItem;
+
+public class JsonRegistryProcessor {
+
+    private static final Logger log = Logger.getLogger(JsonRegistryProcessor.class);
+
+    public static class JsonRegistryEnabled implements BooleanSupplier {
+        MicrometerConfig mConfig;
+
+        public boolean getAsBoolean() {
+            return mConfig.checkRegistryEnabledWithDefault(mConfig.export.json);
+        }
+    }
+
+    @BuildStep(onlyIf = JsonRegistryEnabled.class)
+    @Record(ExecutionTime.STATIC_INIT)
+    public void initializeJsonRegistry(MicrometerConfig config,
+            BuildProducer<MicrometerRegistryProviderBuildItem> registryProviders,
+            BuildProducer<RouteBuildItem> routes,
+            BuildProducer<AdditionalBeanBuildItem> additionalBeans,
+            JsonRecorder recorder,
+            BuildProducer<ReflectiveClassBuildItem> reflectiveClasses) {
+        additionalBeans.produce(AdditionalBeanBuildItem.builder()
+                .addBeanClass(JsonMeterRegistryProvider.class)
+                .setUnremovable().build());
+        registryProviders.produce(new MicrometerRegistryProviderBuildItem(JsonMeterRegistry.class));
+        routes.produce(new RouteBuildItem(recorder.route(config.export.json.path), recorder.getHandler()));
+        reflectiveClasses.produce(ReflectiveClassBuildItem
+                .builder("org.HdrHistogram.Histogram",
+                        "org.HdrHistogram.DoubleHistogram",
+                        "org.HdrHistogram.ConcurrentHistogram")
+                .constructors(true).build());
+        log.debug("Initialized a JSON meter registry on path=" + config.export.json.path);
+    }
+
+}

extensions/micrometer/runtime/pom.xml

@@ -36,6 +36,13 @@
             <artifactId>micrometer-core</artifactId>
         </dependency>
 
+        <!-- Needed for the JSON meter registry -->
+        <dependency>
+            <groupId>org.glassfish</groupId>
+            <artifactId>jakarta.json</artifactId>
+        </dependency>
+
+
         <!-- Registry providers (optional) -->
 
         <dependency>

extensions/micrometer/runtime/src/main/java/io/quarkus/micrometer/runtime/binder/mpmetrics/AnnotatedGaugeAdapter.java

@@ -52,7 +52,7 @@ public GaugeAdapterImpl(String name, String description, String targetName, Stri
         public GaugeAdapterImpl register(MetricDescriptor id, MeterRegistry registry) {
             this.id = id;
             if (gauge == null || metadata.cleanDirtyMetadata()) {
-                gauge = io.micrometer.core.instrument.Gauge.builder(metadata.name, this::getValue)
+                gauge = io.micrometer.core.instrument.Gauge.builder(metadata.name, this, g -> g.getValue().doubleValue())
                         .description(metadata.description())
                         .tags(id.tags())
                         .baseUnit(metadata.unit())

extensions/micrometer/runtime/src/main/java/io/quarkus/micrometer/runtime/binder/mpmetrics/ConcurrentGaugeImpl.java

@@ -14,7 +14,7 @@ class ConcurrentGaugeImpl implements ConcurrentGauge, MeterHolder {
     Gauge gauge;
 
     ConcurrentGaugeImpl register(MpMetadata metadata, MetricDescriptor metricInfo, MeterRegistry registry) {
-        gauge = io.micrometer.core.instrument.Gauge.builder(metricInfo.name(), longAdder::longValue)
+        gauge = io.micrometer.core.instrument.Gauge.builder(metricInfo.name(), longAdder, LongAdder::doubleValue)
                 .description(metadata.description())
                 .baseUnit(metadata.unit())
                 .tags(metricInfo.tags())

extensions/micrometer/runtime/src/main/java/io/quarkus/micrometer/runtime/config/JsonConfig.java

@@ -0,0 +1,52 @@
+package io.quarkus.micrometer.runtime.config;
+
+import java.time.Duration;
+import java.util.Optional;
+
+import io.quarkus.runtime.annotations.ConfigGroup;
+import io.quarkus.runtime.annotations.ConfigItem;
+
+@ConfigGroup
+public class JsonConfig implements MicrometerConfig.CapabilityEnabled {
+    /**
+     * Support for export to JSON format. Off by default.
+     */
+    @ConfigItem(defaultValue = "false")
+    public Optional<Boolean> enabled;
+
+    /**
+     * The path for the JSON metrics endpoint.
+     * The default value is {@code /metrics}.
+     */
+    @ConfigItem(defaultValue = "/metrics")
+    public String path;
+
+    /**
+     * Statistics like max, percentiles, and histogram counts decay over time to give greater weight to recent
+     * samples. Samples are accumulated to such statistics in ring buffers which rotate after
+     * the expiry, with this buffer length.
+     */
+    @ConfigItem(defaultValue = "1024")
+    public Integer bufferLength;
+
+    /**
+     * Statistics like max, percentiles, and histogram counts decay over time to give greater weight to recent
+     * samples. Samples are accumulated to such statistics in ring buffers which rotate after
+     * this expiry, with a particular buffer length.
+     */
+    @ConfigItem(defaultValue = "P3D")
+    public Duration expiry;
+
+    @Override
+    public Optional<Boolean> getEnabled() {
+        return enabled;
+    }
+
+    @Override
+    public String toString() {
+        return this.getClass().getSimpleName()
+                + "{path='" + path
+                + ",enabled=" + enabled
+                + '}';
+    }
+}

extensions/micrometer/runtime/src/main/java/io/quarkus/micrometer/runtime/config/MicrometerConfig.java

@@ -118,6 +118,7 @@ public static class ExportConfig {
         public JmxConfig jmx;
         public PrometheusConfig prometheus;
         public StackdriverConfig stackdriver;
+        public JsonConfig json;
     }
 
     public static interface CapabilityEnabled {

extensions/micrometer/runtime/src/main/java/io/quarkus/micrometer/runtime/export/JsonMeterRegistryProvider.java

@@ -0,0 +1,17 @@
+package io.quarkus.micrometer.runtime.export;
+
+import javax.enterprise.inject.Produces;
+import javax.inject.Singleton;
+
+import io.micrometer.core.instrument.Clock;
+import io.quarkus.micrometer.runtime.registry.json.JsonMeterRegistry;
+
+@Singleton
+public class JsonMeterRegistryProvider {
+
+    @Produces
+    @Singleton
+    public JsonMeterRegistry registry(Clock clock, io.quarkus.micrometer.runtime.config.MicrometerConfig config) {
+        return new JsonMeterRegistry(clock, config.export.json.bufferLength, config.export.json.expiry);
+    }
+}

extensions/micrometer/runtime/src/main/java/io/quarkus/micrometer/runtime/export/JsonRecorder.java

@@ -0,0 +1,30 @@
+package io.quarkus.micrometer.runtime.export;
+
+import java.util.function.Function;
+
+import io.quarkus.micrometer.runtime.export.handlers.JsonHandler;
+import io.quarkus.runtime.annotations.Recorder;
+import io.vertx.ext.web.Route;
+import io.vertx.ext.web.Router;
+
+@Recorder
+public class JsonRecorder {
+    JsonHandler handler;
+
+    public JsonHandler getHandler() {
+        if (handler == null) {
+            handler = new JsonHandler();
+        }
+
+        return handler;
+    }
+
+    public Function<Router, Route> route(String path) {
+        return new Function<Router, Route>() {
+            @Override
+            public Route apply(Router router) {
+                return router.route(path).order(2).produces("application/json");
+            }
+        };
+    }
+}

extensions/micrometer/runtime/src/main/java/io/quarkus/micrometer/runtime/export/PrometheusRecorder.java

@@ -2,7 +2,6 @@
 
 import java.util.function.Function;
 
-import io.prometheus.client.exporter.common.TextFormat;
 import io.quarkus.micrometer.runtime.export.handlers.PrometheusHandler;
 import io.quarkus.runtime.annotations.Recorder;
 import io.vertx.ext.web.Route;
@@ -24,7 +23,7 @@ public Function<Router, Route> route(String path) {
         return new Function<Router, Route>() {
             @Override
             public Route apply(Router router) {
-                return router.route(path).produces(TextFormat.CONTENT_TYPE_004);
+                return router.route(path).order(1).produces("text/plain");
             }
         };
     }

extensions/micrometer/runtime/src/main/java/io/quarkus/micrometer/runtime/export/handlers/JsonHandler.java

@@ -0,0 +1,54 @@
+package io.quarkus.micrometer.runtime.export.handlers;
+
+import javax.enterprise.inject.Default;
+import javax.enterprise.inject.Instance;
+import javax.enterprise.inject.spi.CDI;
+
+import org.jboss.logging.Logger;
+
+import io.quarkus.micrometer.runtime.registry.json.JsonMeterRegistry;
+import io.vertx.core.Handler;
+import io.vertx.core.buffer.Buffer;
+import io.vertx.core.http.HttpServerResponse;
+import io.vertx.ext.web.RoutingContext;
+
+public class JsonHandler implements Handler<RoutingContext> {
+    private static final Logger log = Logger.getLogger(JsonHandler.class);
+
+    private JsonMeterRegistry registry;
+
+    private boolean setup = false;
+
+    @Override
+    public void handle(RoutingContext routingContext) {
+        if (!setup) {
+            setup();
+        }
+
+        HttpServerResponse response = routingContext.response();
+        if (registry == null) {
+            response.setStatusCode(500)
+                    .setStatusMessage("Unable to resolve JSON registry instance");
+        } else {
+            response.putHeader("Content-Type", "application/json")
+                    .end(Buffer.buffer(registry.scrape()));
+        }
+    }
+
+    private void setup() {
+        Instance<JsonMeterRegistry> registries = CDI.current().select(JsonMeterRegistry.class,
+                Default.Literal.INSTANCE);
+
+        if (registries.isUnsatisfied()) {
+            registry = null;
+        } else if (registries.isAmbiguous()) {
+            registry = registries.iterator().next();
+            log.warnf("Multiple JSON registries present: %s. Using %s with the built in scrape endpoint", registries,
+                    registry);
+        } else {
+            registry = registries.get();
+        }
+
+        setup = true;
+    }
+}

extensions/micrometer/runtime/src/main/java/io/quarkus/micrometer/runtime/registry/json/JsonDistributionSummary.java

@@ -0,0 +1,64 @@
+package io.quarkus.micrometer.runtime.registry.json;
+
+import java.util.Arrays;
+import java.util.concurrent.atomic.DoubleAdder;
+import java.util.concurrent.atomic.LongAdder;
+
+import io.micrometer.core.instrument.AbstractDistributionSummary;
+import io.micrometer.core.instrument.Clock;
+import io.micrometer.core.instrument.Measurement;
+import io.micrometer.core.instrument.Statistic;
+import io.micrometer.core.instrument.distribution.DistributionStatisticConfig;
+import io.micrometer.core.instrument.distribution.TimeWindowMax;
+
+public class JsonDistributionSummary extends AbstractDistributionSummary {
+
+    private final LongAdder count;
+    private final DoubleAdder total;
+    private final TimeWindowMax max;
+    private final TimeWindowMin min;
+
+    public JsonDistributionSummary(Id id, Clock clock, DistributionStatisticConfig distributionStatisticConfig,
+            double scale, boolean supportsAggregablePercentiles) {
+        super(id, clock, distributionStatisticConfig, scale, supportsAggregablePercentiles);
+        this.count = new LongAdder();
+        this.total = new DoubleAdder();
+        this.max = new TimeWindowMax(clock, distributionStatisticConfig);
+        this.min = new TimeWindowMin(clock, distributionStatisticConfig);
+    }
+
+    @Override
+    protected void recordNonNegative(double amount) {
+        count.increment();
+        total.add(amount);
+        max.record(amount);
+        min.record(amount);
+    }
+
+    @Override
+    public long count() {
+        return count.longValue();
+    }
+
+    @Override
+    public double totalAmount() {
+        return total.sum();
+    }
+
+    @Override
+    public double max() {
+        return max.poll();
+    }
+
+    public double min() {
+        return min.poll();
+    }
+
+    @Override
+    public Iterable<Measurement> measure() {
+        return Arrays.asList(
+                new Measurement(() -> (double) count(), Statistic.COUNT),
+                new Measurement(this::totalAmount, Statistic.TOTAL),
+                new Measurement(this::max, Statistic.MAX));
+    }
+}