Add Hotspot metrics

build.gradle

@@ -36,6 +36,7 @@ dependencies {
     // You may need to force-disable transitiveness on them.
     implementation "io.prometheus:simpleclient:${project.prometheus_version}"
     implementation "io.prometheus:simpleclient_httpserver:${project.prometheus_version}"
+    implementation "io.prometheus:simpleclient_hotspot:${project.prometheus_version}"
 
     compileOnly "me.lucko:spark-api:0.1-SNAPSHOT"
 }

src/main/java/ru/ruscalworld/fabricexporter/FabricExporter.java

@@ -1,6 +1,7 @@
 package ru.ruscalworld.fabricexporter;
 
 import io.prometheus.client.exporter.HTTPServer;
+import io.prometheus.client.hotspot.DefaultExports;
 import net.fabricmc.api.ModInitializer;
 import net.fabricmc.fabric.api.event.lifecycle.v1.ServerLifecycleEvents;
 import net.fabricmc.loader.api.FabricLoader;
@@ -44,6 +45,10 @@ public class FabricExporter implements ModInitializer {
         metricRegistry.registerDefault();
         this.setMetricRegistry(metricRegistry);
 
+        if (config.shouldExportJvmDefaults()) {
+            DefaultExports.initialize();
+        }
+
         ServerLifecycleEvents.SERVER_STARTING.register(this::setServer);
         ServerLifecycleEvents.SERVER_STARTED.register(server -> {
             try {

src/main/java/ru/ruscalworld/fabricexporter/config/MainConfig.java

@@ -8,6 +8,7 @@ public class MainConfig extends Config {
     private int port;
     private int updateInterval;
     private boolean useSpark;
+    private boolean exportJvmDefaults;
 
     public MainConfig(String name) {
         super(name);
@@ -24,6 +25,8 @@ public class MainConfig extends Config {
         this.setUpdateInterval(ConvertUtil.intToStringOrDefault(updateIntervalString, 1000));
 
         this.setShouldUseSpark(properties.getProperty("use-spark", "true").equalsIgnoreCase("true"));
+
+        this.setShouldExportJvmDefaults(properties.getProperty("export-default-jvm-metrics", "true").equalsIgnoreCase("true"));
     }
 
     public int getPort() {
@@ -49,4 +52,12 @@ public class MainConfig extends Config {
     public void setShouldUseSpark(boolean useSpark) {
         this.useSpark = useSpark;
     }
+
+    public boolean shouldExportJvmDefaults() {
+        return exportJvmDefaults;
+    }
+
+    public void setShouldExportJvmDefaults(boolean exportJvmDefaults) {
+        this.exportJvmDefaults = exportJvmDefaults;
+    }
 }

src/main/resources/config/exporter.properties

@@ -1,4 +1,4 @@
-# On which port webserver should be started?
+# On which port Prometheus webserver should be started?
 # Default: 25585
 server-port=25585
 
@@ -14,6 +14,11 @@ update-interval=1000
 # Default: true
 use-spark=true
 
+# Should FabricExporter register default Hotspot exports?
+# This enables advanced metrics for JVM
+# Default: true
+export-default-jvm-metrics=true
+
 # You can disable any metric that registered via MetricRegistry (all metrics by default) using the settings below
 # Names of properties consist of "enable" and metric name without prefix and "_" replaced with "-"
 # For example, if you want to disable "minecraft_players_online", you should set "enable-players-online" to "false"