Add JVM metrics

Signed-off-by: Fabian Stäber <[email protected]>

Author: fstab

examples/example-exemplars-tail-sampling/example-greeting-service/pom.xml

@@ -37,6 +37,11 @@
             <artifactId>prometheus-metrics-core</artifactId>
             <version>${project.version}</version>
         </dependency>
+        <dependency>
+            <groupId>io.prometheus</groupId>
+            <artifactId>prometheus-metrics-instrumentation-jvm</artifactId>
+            <version>${project.version}</version>
+        </dependency>
         <dependency>
             <groupId>io.prometheus</groupId>
             <artifactId>prometheus-metrics-exporter-servlet-jakarta</artifactId>

examples/example-exemplars-tail-sampling/example-greeting-service/src/main/java/io/prometheus/metrics/examples/otel_exemplars/greeting/Main.java

@@ -1,6 +1,7 @@
 package io.prometheus.metrics.examples.otel_exemplars.greeting;
 
 import io.prometheus.metrics.exporter.servlet.jakarta.PrometheusMetricsServlet;
+import io.prometheus.metrics.instrumentation.jvm.JvmMetrics;
 import org.apache.catalina.Context;
 import org.apache.catalina.LifecycleException;
 import org.apache.catalina.startup.Tomcat;
@@ -14,6 +15,8 @@ public class Main {
 
     public static void main(String[] args) throws LifecycleException {
 
+        JvmMetrics.newBuilder().register();
+
         Tomcat tomcat = new Tomcat();
         tomcat.setPort(8081);
 

examples/example-exemplars-tail-sampling/example-hello-world-app/pom.xml

@@ -37,6 +37,11 @@
             <artifactId>prometheus-metrics-core</artifactId>
             <version>${project.version}</version>
         </dependency>
+        <dependency>
+            <groupId>io.prometheus</groupId>
+            <artifactId>prometheus-metrics-instrumentation-jvm</artifactId>
+            <version>${project.version}</version>
+        </dependency>
         <dependency>
             <groupId>io.prometheus</groupId>
             <artifactId>prometheus-metrics-exporter-servlet-jakarta</artifactId>

examples/example-exemplars-tail-sampling/example-hello-world-app/src/main/java/io/prometheus/metrics/examples/otel_exemplars/app/Main.java

@@ -1,6 +1,7 @@
 package io.prometheus.metrics.examples.otel_exemplars.app;
 
 import io.prometheus.metrics.exporter.servlet.jakarta.PrometheusMetricsServlet;
+import io.prometheus.metrics.instrumentation.jvm.JvmMetrics;
 import org.apache.catalina.Context;
 import org.apache.catalina.LifecycleException;
 import org.apache.catalina.startup.Tomcat;
@@ -14,6 +15,8 @@ public class Main {
 
     public static void main(String[] args) throws LifecycleException {
 
+        JvmMetrics.newBuilder().register();
+
         Tomcat tomcat = new Tomcat();
         tomcat.setPort(8080);
 

examples/example-exporter-httpserver/pom.xml

@@ -37,6 +37,11 @@
             <artifactId>prometheus-metrics-core</artifactId>
             <version>${project.version}</version>
         </dependency>
+        <dependency>
+            <groupId>io.prometheus</groupId>
+            <artifactId>prometheus-metrics-instrumentation-jvm</artifactId>
+            <version>${project.version}</version>
+        </dependency>
         <dependency>
             <groupId>io.prometheus</groupId>
             <artifactId>prometheus-metrics-exporter-httpserver</artifactId>

examples/example-exporter-httpserver/src/main/java/io/prometheus/metrics/examples/httpserver/Main.java

@@ -2,6 +2,7 @@
 
 import io.prometheus.metrics.core.metrics.Counter;
 import io.prometheus.metrics.exporter.httpserver.HTTPServer;
+import io.prometheus.metrics.instrumentation.jvm.JvmMetrics;
 import io.prometheus.metrics.model.snapshots.Unit;
 
 import java.io.IOException;
@@ -13,6 +14,14 @@ public class Main {
 
     public static void main(String[] args) throws IOException, InterruptedException {
 
+        JvmMetrics.newBuilder().register();
+
+        // Note: uptime_seconds_total is not a great example:
+        // The built-in JvmMetrics have an out-of-the-box metric named process_start_time_seconds
+        // with the start timestamp in seconds, so if you want to know the uptime you can simply
+        // run the Prometheus query
+        //     time() - process_start_time_seconds
+        // rather than creating a custom uptime metric.
         Counter counter = Counter.newBuilder()
                 .withName("uptime_seconds_total")
                 .withHelp("total number of seconds since this application was started")

examples/example-exporter-opentelemetry/pom.xml

@@ -37,6 +37,11 @@
             <artifactId>prometheus-metrics-core</artifactId>
             <version>${project.version}</version>
         </dependency>
+        <dependency>
+            <groupId>io.prometheus</groupId>
+            <artifactId>prometheus-metrics-instrumentation-jvm</artifactId>
+            <version>${project.version}</version>
+        </dependency>
         <dependency>
             <groupId>io.prometheus</groupId>
             <artifactId>prometheus-metrics-exporter-opentelemetry</artifactId>

examples/example-exporter-opentelemetry/src/main/java/io/prometheus/metrics/examples/opentelemetry/Main.java

@@ -2,6 +2,7 @@
 
 import io.prometheus.metrics.core.metrics.Counter;
 import io.prometheus.metrics.exporter.opentelemetry.OpenTelemetryExporter;
+import io.prometheus.metrics.instrumentation.jvm.JvmMetrics;
 import io.prometheus.metrics.model.snapshots.Unit;
 
 /**
@@ -11,6 +12,17 @@ public class Main {
 
     public static void main(String[] args) throws Exception {
 
+        // Note: Some JVM metrics are also defined as OpenTelemetry's semantic conventions.
+        // We have plans to implement a configuration option for JvmMetrics to use OpenTelemetry
+        // naming conventions rather than the Prometheus names.
+        JvmMetrics.newBuilder().register();
+
+        // Note: uptime_seconds_total is not a great example:
+        // The built-in JvmMetrics have an out-of-the-box metric named process_start_time_seconds
+        // with the start timestamp in seconds, so if you want to know the uptime you can simply
+        // run the Prometheus query
+        //     time() - process_start_time_seconds
+        // rather than creating a custom uptime metric.
         Counter counter = Counter.newBuilder()
                 .withName("uptime_seconds_total")
                 .withHelp("total number of seconds since this application was started")

examples/example-exporter-servlet-tomcat/pom.xml

@@ -37,6 +37,11 @@
             <artifactId>prometheus-metrics-core</artifactId>
             <version>${project.version}</version>
         </dependency>
+        <dependency>
+            <groupId>io.prometheus</groupId>
+            <artifactId>prometheus-metrics-instrumentation-jvm</artifactId>
+            <version>${project.version}</version>
+        </dependency>
         <dependency>
             <groupId>io.prometheus</groupId>
             <artifactId>prometheus-metrics-exporter-servlet-jakarta</artifactId>

examples/example-exporter-servlet-tomcat/src/main/java/io/prometheus/metrics/examples/tomcat_servlet/HelloWorldServlet.java

@@ -19,6 +19,8 @@ public class HelloWorldServlet extends HttpServlet {
 
     private final Random random = new Random(0);
 
+    // Note: The requests_total counter is not a great example, because the
+    // request_duration_seconds histogram below also has a count with the number of requests.
     private final Counter counter = Counter.newBuilder()
             .withName("requests_total")
             .withHelp("total number of requests")