KAFKA-16814 KRaft broker cannot startup when partition.metadata is missing

core/src/main/scala/kafka/log/LogManager.scala

@@ -1604,11 +1604,16 @@ object LogManager {
    newTopicsImage: TopicsImage,
    log: UnifiedLog
   ): Boolean = {
-    val topicId = log.topicId.getOrElse {
-      throw new RuntimeException(s"The log dir $log does not have a topic ID, " +
-        "which is not allowed when running in KRaft mode.")
+    if (log.topicId.isEmpty) {
+      // Missing topic ID could result from storage failure or unclean shutdown after topic creation but before flushing
+      // data to the `partition.metadata` file. And before appending data to the log, the `partition.metadata` is always
+      // flushed to disk. So if the topic ID is missing, it mostly means no data was appended, and we can treat this as
+      // a stray log directory.
+      info(s"The topicId does not exist in $log, treat it as stray log dir")
+      return true
     }
 
+    val topicId = log.topicId.get
     val partitionId = log.topicPartition.partition()
     Option(newTopicsImage.getPartition(topicId, partitionId)) match {
       case Some(partition) =>

core/src/test/java/kafka/server/LogManagerIntegrationTest.java

@@ -0,0 +1,107 @@
+/*
+ * 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 kafka.server;
+
+import kafka.test.ClusterInstance;
+import kafka.test.annotation.ClusterTest;
+import kafka.test.annotation.Type;
+import kafka.test.junit.ClusterTestExtensions;
+import kafka.test.junit.RaftClusterInvocationContext;
+import org.apache.kafka.clients.admin.Admin;
+import org.apache.kafka.clients.admin.NewTopic;
+import org.apache.kafka.clients.consumer.Consumer;
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+import org.apache.kafka.clients.consumer.ConsumerRecords;
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.clients.producer.KafkaProducer;
+import org.apache.kafka.clients.producer.Producer;
+import org.apache.kafka.clients.producer.ProducerConfig;
+import org.apache.kafka.clients.producer.ProducerRecord;
+import org.apache.kafka.common.TopicPartition;
+import org.apache.kafka.common.serialization.StringDeserializer;
+import org.apache.kafka.common.serialization.StringSerializer;
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import java.io.IOException;
+import java.time.Duration;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.UUID;
+import java.util.concurrent.ExecutionException;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+@ExtendWith(value = ClusterTestExtensions.class)
+@Tag("integration")
+public class LogManagerIntegrationTest {
+    private final ClusterInstance cluster;
+
+    public LogManagerIntegrationTest(ClusterInstance cluster) {
+        this.cluster = cluster;
+    }
+
+    @ClusterTest(types = {Type.KRAFT})
+    public void testRestartBrokerNoErrorIfMissingPartitionMetadata() throws IOException, ExecutionException, InterruptedException {
+        RaftClusterInvocationContext.RaftClusterInstance raftInstance = (RaftClusterInvocationContext.RaftClusterInstance) cluster;
+
+        try (Admin admin = cluster.createAdminClient()) {
+            admin.createTopics(Collections.singletonList(new NewTopic("foo", 1, (short) 1)));
+        }
+
+        raftInstance.getUnderlying().brokers().get(0).shutdown();
+        // delete partition.metadata file here to simulate the scenario that partition.metadata not flush to disk yet
+        raftInstance.getUnderlying().brokers().get(0)
+                .logManager().getLog(new TopicPartition("foo", 0), false).get().partitionMetadataFile().get().delete();
+        raftInstance.getUnderlying().brokers().get(0).startup();
+        assertDoesNotThrow(() -> raftInstance.getUnderlying().fatalFaultHandler().maybeRethrowFirstException());
+
+        // make sure topic still work fine
+        Map<String, Object> producerConfigs = new HashMap<>();
+        producerConfigs.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, cluster.bootstrapServers());
+        producerConfigs.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
+        producerConfigs.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
+
+        try (Producer<String, String> producer = new KafkaProducer<>(producerConfigs)) {
+            producer.send(new ProducerRecord<>("foo", 0, null, "bar")).get();
+            producer.flush();
+        }
+
+        Map<String, Object> consumerConfigs = new HashMap<>();
+        consumerConfigs.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, cluster.bootstrapServers());
+        consumerConfigs.put(ConsumerConfig.GROUP_ID_CONFIG, UUID.randomUUID().toString());
+        consumerConfigs.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
+        consumerConfigs.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
+
+        try (Consumer<String, String> consumer = new KafkaConsumer<>(consumerConfigs)) {
+            consumer.assign(Collections.singletonList(new TopicPartition("foo", 0)));
+            consumer.seekToBeginning(Collections.singletonList(new TopicPartition("foo", 0)));
+            List<String> values = new ArrayList<>();
+            ConsumerRecords<String, String> records = consumer.poll(Duration.ofMinutes(1));
+            for (ConsumerRecord<String, String> record : records) {
+                values.add(record.value());
+            }
+            assertEquals(1, values.size());
+            assertEquals("bar", values.get(0));
+        }
+    }
+}

core/src/test/scala/unit/kafka/log/LogManagerTest.scala

@@ -1286,6 +1286,13 @@ class LogManagerTest {
     onDisk.foreach(log => assertEquals(expectedStrays.contains(log.topicPartition), LogManager.isStrayKraftReplica(0, image, log)))
   }
 
+  @Test
+  def testIsStrayKraftMissingTopicId(): Unit = {
+    val log = Mockito.mock(classOf[UnifiedLog])
+    Mockito.when(log.topicId).thenReturn(Option.empty)
+    assertTrue(LogManager.isStrayKraftReplica(0, topicsImage(Seq()), log))
+  }
+
   @Test
   def testFindStrayReplicasInEmptyLAIR(): Unit = {
     val onDisk = Seq(foo0, foo1, bar0, bar1, baz0, baz1, baz2, quux0)