feat: Emit git commit metric and add a commit version to sys.servers for validations

docs/operations/metrics.md

@@ -31,6 +31,8 @@ All Druid metrics share a common set of fields:
 * `metric`: the name of the metric
 * `service`: the service name that emitted the metric
 * `host`: the host name that emitted the metric
+* `version`: the Druid version of the service that emitted the metric
+* `buildRevision`: the git commit of the build that produced the service binary. Useful for verifying that all nodes in a cluster are running the intended revision during rolling deployments. Empty string when running outside a packaged binary (e.g., during `mvn test`).
 * `value`: some numeric value associated with the metric
 
 Metrics may have additional dimensions beyond those listed above.

docs/querying/sql-metadata-tables.md

@@ -237,6 +237,7 @@ Servers table lists all discovered servers in the cluster.
 |is_leader|BIGINT|1 if the server is currently the 'leader' (for services which have the concept of leadership), otherwise 0 if the server is not the leader, or null if the server type does not have the concept of leadership|
 |start_time|STRING|Timestamp in ISO8601 format when the server was announced in the cluster|
 |version|VARCHAR|Druid version running on the server|
+|build_revision|VARCHAR|The git commit of the build that produced the server binary. Empty string when running outside a packaged binary (e.g., during `mvn test`)|
 |labels|VARCHAR|Labels for the server configured using the property [`druid.labels`](../configuration/index.md)|
 |available_processors|BIGINT|Total number of CPU processors available to the server|
 |total_memory|BIGINT|Total memory in bytes available to the server|

pom.xml

@@ -1885,7 +1885,7 @@
                     </execution>
                 </executions>
                 <configuration>
-                    <dotGitDirectory>${project.basedir}/.git</dotGitDirectory>
+                    <dotGitDirectory>${session.executionRootDirectory}/.git</dotGitDirectory>
                     <dateFormatTimeZone>Etc/UTC</dateFormatTimeZone>
                     <skipPoms>false</skipPoms>
                     <format>json</format>

server/src/main/java/org/apache/druid/server/DruidNode.java

@@ -29,16 +29,21 @@
 import org.apache.druid.common.utils.SocketUtil;
 import org.apache.druid.java.util.common.IAE;
 import org.apache.druid.java.util.common.ISE;
+import org.apache.druid.java.util.common.StringUtils;
 
 import javax.annotation.Nullable;
 import javax.validation.constraints.Max;
 import javax.validation.constraints.NotNull;
+import java.io.IOException;
+import java.io.InputStream;
 import java.net.InetAddress;
 import java.net.URI;
 import java.net.URISyntaxException;
+import java.net.URL;
 import java.net.UnknownHostException;
 import java.util.Map;
 import java.util.Objects;
+import java.util.jar.Manifest;
 
 /**
  *
@@ -92,6 +97,10 @@ public class DruidNode
       UNKNOWN_VERSION
   );
 
+  @JsonProperty
+  @NotNull
+  private final String buildRevision = StringUtils.nullToEmptyNonDruidDataString(readBuildRevisionFromManifest());
+
   @JsonProperty
   private Map<String, String> labels;
 
@@ -266,6 +275,33 @@ public String getVersion()
     return version;
   }
 
+  public String getBuildRevision()
+  {
+    return buildRevision;
+  }
+
+  /**
+   * Reads the {@code Build-Revision} attribute from the MANIFEST.MF of the JAR containing this class.
+   * Returns null when running outside a packaged JAR (e.g., during {@code mvn test}).
+   */
+  private static String readBuildRevisionFromManifest()
+  {
+    try {
+      URL classUrl = DruidNode.class.getResource(DruidNode.class.getSimpleName() + ".class");
+      if (classUrl != null && "jar".equals(classUrl.getProtocol())) {
+        String classPath = classUrl.toString();
+        String manifestPath = classPath.substring(0, classPath.lastIndexOf('!') + 1) + "/META-INF/MANIFEST.MF";
+        try (InputStream is = new URL(manifestPath).openStream()) {
+          return new Manifest(is).getMainAttributes().getValue("Build-Revision");
+        }
+      }
+    }
+    catch (IOException e) {
+      // Fall through and return null
+    }
+    return null;
+  }
+
   public DruidNode withService(String service)
   {
     return new DruidNode(service, host, bindOnHost, plaintextPort, tlsPort, enablePlaintextPort, enableTlsPort);

server/src/main/java/org/apache/druid/server/emitter/EmitterModule.java

@@ -45,11 +45,15 @@
 import org.apache.druid.java.util.metrics.TaskHolder;
 import org.apache.druid.server.DruidNode;
 
+import java.io.IOException;
+import java.io.InputStream;
 import java.lang.annotation.Annotation;
+import java.net.URL;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.Properties;
+import java.util.jar.Manifest;
 
 /**
  *
@@ -92,6 +96,9 @@ public void configure(Binder binder)
     extraServiceDimensions
         .addBinding("version")
         .toInstance(StringUtils.nullToEmptyNonDruidDataString(version)); // Version is null during `mvn test`.
+    extraServiceDimensions
+        .addBinding("buildRevision")
+        .toInstance(StringUtils.nullToEmptyNonDruidDataString(getBuildRevision()));
   }
 
   @Provides
@@ -177,4 +184,26 @@ public Emitter get()
       return emitter;
     }
   }
+
+  /**
+   * Reads the {@code Build-Revision} attribute from the MANIFEST.MF of the JAR that contains this class.
+   * Returns null when running outside a packaged JAR (e.g., during {@code mvn test}).
+   */
+  protected String getBuildRevision()
+  {
+    try {
+      URL classUrl = EmitterModule.class.getResource(EmitterModule.class.getSimpleName() + ".class");
+      if (classUrl != null && "jar".equals(classUrl.getProtocol())) {
+        String classPath = classUrl.toString();
+        String manifestPath = classPath.substring(0, classPath.lastIndexOf('!') + 1) + "/META-INF/MANIFEST.MF";
+        try (InputStream is = new URL(manifestPath).openStream()) {
+          return new Manifest(is).getMainAttributes().getValue("Build-Revision");
+        }
+      }
+    }
+    catch (IOException e) {
+      // Fall through and return null
+    }
+    return null;
+  }
 }

server/src/test/java/org/apache/druid/server/emitter/EmitterModuleTest.java

@@ -205,4 +205,75 @@ public void configure(Binder binder)
         )
     );
   }
+
+  @Test
+  public void testBuildRevisionDimensionEmitsKnownValue()
+  {
+    // EmitterModule with a known revision verifies that getBuildRevision() is wired into the buildRevision dimension.
+    EmitterModule emitterModule = new EmitterModule()
+    {
+      @Override
+      protected String getBuildRevision()
+      {
+        return "abc1234def567890";
+      }
+    };
+    Injector injector = makeInjectorForEmitterModule(emitterModule);
+    ServiceEmitter serviceEmitter = injector.getInstance(ServiceEmitter.class);
+    serviceEmitter.start();
+    serviceEmitter.emit(new ServiceMetricEvent.Builder().setMetric("test", 1));
+
+    StubServiceEmitter stubEmitter = (StubServiceEmitter) injector.getInstance(Emitter.class);
+    EventMap map = ((ServiceMetricEvent) stubEmitter.getEvents().get(0)).toMap();
+    Assert.assertEquals("abc1234def567890", map.get("buildRevision"));
+  }
+
+  @Test
+  public void testBuildRevisionDimensionFallsBackToEmptyStringWhenUnavailable()
+  {
+    // When getBuildRevision() returns null (e.g. manifest absent), buildRevision dimension is an empty string,
+    // consistent with how the "version" dimension behaves during `mvn test`.
+    EmitterModule emitterModule = new EmitterModule()
+    {
+      @Override
+      protected String getBuildRevision()
+      {
+        return null;
+      }
+    };
+    Injector injector = makeInjectorForEmitterModule(emitterModule);
+    ServiceEmitter serviceEmitter = injector.getInstance(ServiceEmitter.class);
+    serviceEmitter.start();
+    serviceEmitter.emit(new ServiceMetricEvent.Builder().setMetric("test", 1));
+
+    StubServiceEmitter stubEmitter = (StubServiceEmitter) injector.getInstance(Emitter.class);
+    EventMap map = ((ServiceMetricEvent) stubEmitter.getEvents().get(0)).toMap();
+    Assert.assertEquals("", map.get("buildRevision"));
+  }
+
+  private Injector makeInjectorForEmitterModule(EmitterModule emitterModule)
+  {
+    Properties props = new Properties();
+    props.setProperty("druid.emitter", "stub");
+    emitterModule.setProps(props);
+    return Guice.createInjector(
+        new JacksonModule(),
+        new LifecycleModule(),
+        binder -> {
+          JsonConfigProvider.bindInstance(
+              binder,
+              Key.get(DruidNode.class, Self.class),
+              new DruidNode("test-service", "localhost", false, 8080, null, true, false)
+          );
+          binder.bind(Validator.class).toInstance(Validation.buildDefaultValidatorFactory().getValidator());
+          binder.bindScope(LazySingleton.class, Scopes.SINGLETON);
+          binder.bind(Properties.class).toInstance(props);
+          binder.bind(TaskHolder.class).toInstance(new TestTaskHolder("test", "id1", "type1", "group1"));
+          binder.bind(LoadSpecHolder.class).to(DefaultLoadSpecHolder.class).in(LazySingleton.class);
+        },
+        ServerInjectorBuilder.registerNodeRoleModule(ImmutableSet.of()),
+        emitterModule,
+        new StubServiceEmitterModule()
+    );
+  }
 }

sql/src/main/java/org/apache/druid/sql/calcite/schema/SystemSchema.java

@@ -192,6 +192,7 @@ public class SystemSchema extends AbstractSchema
       .add("is_leader", ColumnType.LONG)
       .add("start_time", ColumnType.STRING)
       .add("version", ColumnType.STRING)
+      .add("build_revision", ColumnType.STRING)
       .add("labels", ColumnType.STRING)
       .add("available_processors", ColumnType.LONG)
       .add("total_memory", ColumnType.LONG)
@@ -697,6 +698,7 @@ private Object[] buildRowForNonDataServer(DiscoveryDruidNode discoveryDruidNode)
           null,
           toStringOrNull(discoveryDruidNode.getStartTime()),
           node.getVersion(),
+          node.getBuildRevision(),
           node.getLabels() == null ? null : JacksonUtils.writeValueAsString(jsonMapper, node.getLabels()),
           (long) discoveryDruidNode.getAvailableProcessors(),
           discoveryDruidNode.getTotalMemory()
@@ -725,6 +727,7 @@ private Object[] buildRowForNonDataServerWithLeadership(
           isLeader ? 1L : 0L,
           toStringOrNull(discoveryDruidNode.getStartTime()),
           node.getVersion(),
+          node.getBuildRevision(),
           node.getLabels() == null ? null : JacksonUtils.writeValueAsString(jsonMapper, node.getLabels()),
           (long) discoveryDruidNode.getAvailableProcessors(),
           discoveryDruidNode.getTotalMemory()
@@ -765,6 +768,7 @@ private Object[] buildRowForDiscoverableDataServer(
           null,
           toStringOrNull(discoveryDruidNode.getStartTime()),
           node.getVersion(),
+          node.getBuildRevision(),
           node.getLabels() == null ? null : JacksonUtils.writeValueAsString(jsonMapper, node.getLabels()),
           (long) discoveryDruidNode.getAvailableProcessors(),
           discoveryDruidNode.getTotalMemory()