Registering JMX Exporter build info

collector/src/main/java/io/prometheus/jmx/BuildInfoCollector.java

@@ -0,0 +1,46 @@
+package io.prometheus.jmx;
+
+import io.prometheus.client.Collector;
+import io.prometheus.client.GaugeMetricFamily;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static java.util.Arrays.asList;
+
+/**
+ * Collects jmx_exporter build version info.
+ * <p>
+ * Example usage:
+ * <pre>
+ * {@code
+ *   new BuildInfoCollector().register();
+ * }
+ * </pre>
+ * Metrics being exported:
+ * <pre>
+ *   jmx_exporter_build_info{version="3.2.0",name="jmx_prometheus_httpserver",} 1.0
+ * </pre>
+ */
+public class BuildInfoCollector extends Collector {
+  public List<Collector.MetricFamilySamples> collect() {
+    List<Collector.MetricFamilySamples> mfs = new ArrayList<Collector.MetricFamilySamples>();
+
+    GaugeMetricFamily artifactInfo = new GaugeMetricFamily(
+            "jmx_exporter_build_info",
+            "A metric with a constant '1' value labeled with the version of the JMX exporter.",
+            asList("version", "name"));
+
+    Package pkg = this.getClass().getPackage();
+    String version = pkg.getImplementationVersion();
+    String name = pkg.getImplementationTitle();
+
+    artifactInfo.addMetric(asList(
+            version != null ? version : "unknown",
+            name != null ? name : "unknown"
+    ), 1L);
+    mfs.add(artifactInfo);
+
+    return mfs;
+  }
+}

collector/src/test/java/io/prometheus/jmx/BuildInfoCollectorTest.java

@@ -0,0 +1,32 @@
+package io.prometheus.jmx;
+
+import io.prometheus.client.CollectorRegistry;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class BuildInfoCollectorTest {
+
+  private CollectorRegistry registry = new CollectorRegistry();
+
+  @Before
+  public void setUp() {
+    new BuildInfoCollector().register(registry);
+  }
+
+  @Test
+  public void testBuildInfo() {
+    String version = this.getClass().getPackage().getImplementationVersion();
+    String name = this.getClass().getPackage().getImplementationTitle();
+
+    assertEquals(
+            1L,
+            registry.getSampleValue(
+                    "jmx_exporter_build_info", new String[]{"version", "name"}, new String[]{
+                            version != null ? version : "unknown",
+                            name != null ? name : "unknown"
+                    }),
+            .0000001);
+  }
+}

jmx_prometheus_httpserver/pom.xml

@@ -36,6 +36,7 @@
           <archive>
             <manifest>
               <mainClass>io.prometheus.jmx.WebServer</mainClass>
+              <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
             </manifest>
           </archive>
           <descriptorRefs>

jmx_prometheus_httpserver/src/main/java/io/prometheus/jmx/WebServer.java

@@ -26,6 +26,7 @@ public static void main(String[] args) throws Exception {
        socket = new InetSocketAddress(port);
      }
 
+     new BuildInfoCollector().register();
      new JmxCollector(new File(args[1])).register();
      new HTTPServer(socket, CollectorRegistry.defaultRegistry);
    }

jmx_prometheus_javaagent/pom.xml

@@ -82,6 +82,8 @@
             <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
              <manifestEntries>
               <Premain-Class>io.prometheus.jmx.shaded.io.prometheus.jmx.JavaAgent</Premain-Class>
+              <Implementation-Version>${project.version}</Implementation-Version>
+              <Implementation-Title>${project.artifactId}</Implementation-Title>
              </manifestEntries>
             </transformer>
           </transformers>

jmx_prometheus_javaagent/src/main/java/io/prometheus/jmx/JavaAgent.java

@@ -44,6 +44,7 @@ public static void premain(String agentArgument, Instrumentation instrumentation
        file = args[1];
      }
 
+     new BuildInfoCollector().register();
      new JmxCollector(new File(file)).register();
      DefaultExports.initialize();
      server = new HTTPServer(socket, CollectorRegistry.defaultRegistry, true);