Remove mandatory beam-sdks-io-kafka dependency for dataflow worker jar

runners/google-cloud-dataflow-java/worker/build.gradle

@@ -54,7 +54,6 @@ def sdk_provided_project_dependencies = [
         ":runners:google-cloud-dataflow-java",
         ":sdks:java:extensions:avro",
         ":sdks:java:extensions:google-cloud-platform-core",
-        ":sdks:java:io:kafka", // For metric propagation into worker
         ":sdks:java:io:google-cloud-platform",
 ]
 

runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/MetricsToPerStepNamespaceMetricsConverter.java

@@ -32,7 +32,6 @@
 import java.util.Map.Entry;
 import java.util.Optional;
 import org.apache.beam.sdk.io.gcp.bigquery.BigQuerySinkMetrics;
-import org.apache.beam.sdk.io.kafka.KafkaSinkMetrics;
 import org.apache.beam.sdk.metrics.LabeledMetricNameUtils;
 import org.apache.beam.sdk.metrics.MetricName;
 import org.apache.beam.sdk.util.HistogramData;
@@ -43,6 +42,9 @@
  * converter.
  */
 public class MetricsToPerStepNamespaceMetricsConverter {
+  // Avoids to introduce mandatory kafka-io dependency to Dataflow worker
+  // keep in sync with org.apache.beam.sdk.io.kafka.KafkaSinkMetrics.METRICS_NAMESPACE
+  public static String KAFKA_SINK_METRICS_NAMESPACE = "KafkaSink";
 
   private static Optional<LabeledMetricNameUtils.ParsedMetricName> getParsedMetricName(
       MetricName metricName,
@@ -70,7 +72,7 @@ private static Optional<MetricValue> convertCounterToMetricValue(
 
     if (value == 0
         || (!metricName.getNamespace().equals(BigQuerySinkMetrics.METRICS_NAMESPACE)
-            && !metricName.getNamespace().equals(KafkaSinkMetrics.METRICS_NAMESPACE))) {
+            && !metricName.getNamespace().equals(KAFKA_SINK_METRICS_NAMESPACE))) {
       return Optional.empty();
     }
 

runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/StreamingDataflowWorker.java

@@ -110,7 +110,6 @@
 import org.apache.beam.sdk.fn.JvmInitializers;
 import org.apache.beam.sdk.io.FileSystems;
 import org.apache.beam.sdk.io.gcp.bigquery.BigQuerySinkMetrics;
-import org.apache.beam.sdk.io.kafka.KafkaSinkMetrics;
 import org.apache.beam.sdk.metrics.MetricsEnvironment;
 import org.apache.beam.sdk.util.construction.CoderTranslation;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.annotations.VisibleForTesting;
@@ -835,10 +834,6 @@ public static void main(String[] args) throws Exception {
       enableBigQueryMetrics();
     }
 
-    if (DataflowRunner.hasExperiment(options, "enable_kafka_metrics")) {
-      KafkaSinkMetrics.setSupportKafkaMetrics(true);
-    }
-
     JvmInitializers.runBeforeProcessing(options);
     worker.startStatusPages();
     worker.start();

runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/streaming/StageInfo.java

@@ -17,6 +17,7 @@
  */
 package org.apache.beam.runners.dataflow.worker.streaming;
 
+import static org.apache.beam.runners.dataflow.worker.MetricsToPerStepNamespaceMetricsConverter.KAFKA_SINK_METRICS_NAMESPACE;
 import static org.apache.beam.sdk.metrics.Metrics.THROTTLE_TIME_COUNTER_NAME;
 
 import com.google.api.services.dataflow.model.CounterStructuredName;
@@ -35,7 +36,6 @@
 import org.apache.beam.runners.dataflow.worker.counters.DataflowCounterUpdateExtractor;
 import org.apache.beam.runners.dataflow.worker.counters.NameContext;
 import org.apache.beam.sdk.io.gcp.bigquery.BigQuerySinkMetrics;
-import org.apache.beam.sdk.io.kafka.KafkaSinkMetrics;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Iterables;
 
 /** Contains a few of the stage specific fields. E.g. metrics container registry, counters etc. */
@@ -120,8 +120,7 @@ private void translateKnownPerWorkerCounters(List<PerStepNamespaceMetrics> metri
     for (PerStepNamespaceMetrics perStepnamespaceMetrics : metrics) {
       if (!BigQuerySinkMetrics.METRICS_NAMESPACE.equals(
               perStepnamespaceMetrics.getMetricsNamespace())
-          && !KafkaSinkMetrics.METRICS_NAMESPACE.equals(
-              perStepnamespaceMetrics.getMetricsNamespace())) {
+          && !KAFKA_SINK_METRICS_NAMESPACE.equals(perStepnamespaceMetrics.getMetricsNamespace())) {
         continue;
       }
       for (MetricValue metric : perStepnamespaceMetrics.getMetricValues()) {

sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/KafkaIOInitializer.java

@@ -0,0 +1,34 @@
+/*
+ * 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.beam.sdk.io.kafka;
+
+import com.google.auto.service.AutoService;
+import org.apache.beam.sdk.harness.JvmInitializer;
+import org.apache.beam.sdk.options.ExperimentalOptions;
+import org.apache.beam.sdk.options.PipelineOptions;
+
+/** Initialize KafkaIO feature flags on worker. */
+@AutoService(JvmInitializer.class)
+public class KafkaIOInitializer implements JvmInitializer {
+  @Override
+  public void beforeProcessing(PipelineOptions options) {
+    if (ExperimentalOptions.hasExperiment(options, "enable_kafka_metrics")) {
+      KafkaSinkMetrics.setSupportKafkaMetrics(true);
+    }
+  }
+}