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.
 * `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|
 |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|

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

@@ -0,0 +1,73 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.server;
+
+import org.apache.druid.java.util.common.logger.Logger;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+import java.util.jar.Manifest;
+
+/**
+ * Utility class for reading build metadata from the JAR manifest.
+ */
+public class BuildInfo
+{
+  private static final Logger log = new Logger(BuildInfo.class);
+
+  private BuildInfo()
+  {
+    // Utility class; do not instantiate.
+  }
+
+  /**
+   * Reads the {@code Build-Revision} attribute from the {@code META-INF/MANIFEST.MF} of the JAR
+   * that contains this class. Returns an empty string when running outside a packaged JAR
+   * (e.g., during {@code mvn test}).
+   */
+  public static String getBuildRevision()
+  {
+    try {
+      URL classUrl = BuildInfo.class.getResource(BuildInfo.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 readRevisionFromManifest(is);
+        }
+      }
+    }
+    catch (IOException e) {
+      log.warn(e, "Failed to read Build-Revision from JAR manifest");
+    }
+    return "";
+  }
+
+  /**
+   * Reads the {@code Build-Revision} attribute from a manifest {@link InputStream}.
+   * Returns an empty string if the attribute is absent.
+   */
+  static String readRevisionFromManifest(InputStream is) throws IOException
+  {
+    String revision = new Manifest(is).getMainAttributes().getValue("Build-Revision");
+    return revision != null ? revision : "";
+  }
+}

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

@@ -92,6 +92,10 @@ public class DruidNode
       UNKNOWN_VERSION
   );
 
+  @JsonProperty
+  @NotNull
+  private final String buildRevision = BuildInfo.getBuildRevision();
+
   @JsonProperty
   private Map<String, String> labels;
 
@@ -266,6 +270,11 @@ public String getVersion()
     return version;
   }
 
+  public String getBuildRevision()
+  {
+    return buildRevision;
+  }
+
   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

@@ -43,6 +43,7 @@
 import org.apache.druid.java.util.emitter.core.Emitter;
 import org.apache.druid.java.util.emitter.service.ServiceEmitter;
 import org.apache.druid.java.util.metrics.TaskHolder;
+import org.apache.druid.server.BuildInfo;
 import org.apache.druid.server.DruidNode;
 
 import java.lang.annotation.Annotation;
@@ -92,6 +93,9 @@ public void configure(Binder binder)
     extraServiceDimensions
         .addBinding("version")
         .toInstance(StringUtils.nullToEmptyNonDruidDataString(version)); // Version is null during `mvn test`.
+    extraServiceDimensions
+        .addBinding("buildRevision")
+        .toInstance(getBuildRevision());
   }
 
   @Provides
@@ -177,4 +181,13 @@ public Emitter get()
       return emitter;
     }
   }
+
+  /**
+   * Returns the {@code Build-Revision} for the current build, delegating to {@link BuildInfo}.
+   * Overridable for testing.
+   */
+  protected String getBuildRevision()
+  {
+    return BuildInfo.getBuildRevision();
+  }
 }

server/src/test/java/org/apache/druid/server/BuildInfoTest.java

@@ -0,0 +1,54 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.server;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+
+public class BuildInfoTest
+{
+  @Test
+  public void testGetBuildRevisionReturnsEmptyStringOutsideJar()
+  {
+    // During mvn test the class loads from the filesystem, not a JAR, so this must return "".
+    Assert.assertEquals("", BuildInfo.getBuildRevision());
+  }
+
+  @Test
+  public void testReadRevisionFromManifestWithRevisionPresent() throws IOException
+  {
+    String manifest = "Manifest-Version: 1.0\nBuild-Revision: abc123\n\n";
+    InputStream is = new ByteArrayInputStream(manifest.getBytes(StandardCharsets.UTF_8));
+    Assert.assertEquals("abc123", BuildInfo.readRevisionFromManifest(is));
+  }
+
+  @Test
+  public void testReadRevisionFromManifestWithRevisionAbsent() throws IOException
+  {
+    String manifest = "Manifest-Version: 1.0\n\n";
+    InputStream is = new ByteArrayInputStream(manifest.getBytes(StandardCharsets.UTF_8));
+    Assert.assertEquals("", BuildInfo.readRevisionFromManifest(is));
+  }
+}

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

@@ -205,4 +205,74 @@ 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 "" (e.g. running outside a packaged JAR), buildRevision dimension is an empty string.
+    EmitterModule emitterModule = new EmitterModule()
+    {
+      @Override
+      protected String getBuildRevision()
+      {
+        return "";
+      }
+    };
+    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()