feat: Transactional Produces to Command Topic

config/ksql-production-server.properties

@@ -74,9 +74,11 @@ ksql.streams.producer.delivery.timeout.ms=2147483647
 # Kafka cluster is unavailable.
 ksql.streams.producer.max.block.ms=9223372036854775807
 
-# For better fault tolerance and durability, set the replication factor for the KSQL
-# Server's internal topics. Note: the value 3 requires at least 3 brokers in your Kafka cluster.
+# For better fault tolerance and durability, set the replication factor and minimum insync replicas
+# for the KSQL Server's internal topics.
+# Note: the value 3 requires at least 3 brokers in your Kafka cluster.
 ksql.internal.topic.replicas=3
+ksql.internal.topic.min.insync.replicas=2
 
 # Configure underlying Kafka Streams internal topics in order to achieve better fault tolerance and
 # durability, even in the face of Kafka broker failures. Highly recommended for mission critical applications.

docs/installation/server-config/security.rst

@@ -404,6 +404,9 @@ The ACLs required are the same for both :ref:`Interactive and non-interactive (h
 KSQL always requires the following ACLs for its internal operations and data management:
 
 - The ``DESCRIBE_CONFIGS`` operation on the ``CLUSTER`` resource type.
+- The ``DESCRIBE`` operation on the ``TOPIC`` with ``LITERAL`` name ``__consumer_offsets``.
+- The ``DESCRIBE`` operation on the ``TOPIC`` with ``LITERAL`` name ``__transaction_state``.
+- The ``DESCRIBE`` and ``WRITE`` operations on the ``TRANSACTIONAL_ID`` with ``LITERAL`` name ``<ksql.service.id>``.
 - The ``ALL`` operation on all internal ``TOPICS`` that are ``PREFIXED`` with ``_confluent-ksql-<ksql.service.id>``.
 - The ``ALL`` operation on all internal ``GROUPS`` that are ``PREFIXED`` with ``_confluent-ksql-<ksql.service.id>``.
 

ksql-common/src/main/java/io/confluent/ksql/util/KsqlConfig.java

@@ -65,6 +65,9 @@ public class KsqlConfig extends AbstractConfig {
 
   public static final String KSQL_INTERNAL_TOPIC_REPLICAS_PROPERTY = "ksql.internal.topic.replicas";
 
+  public static final String KSQL_INTERNAL_TOPIC_MIN_INSYNC_REPLICAS_PROPERTY = 
+      "ksql.internal.topic.min.insync.replicas";
+
   public static final String KSQL_SCHEMA_REGISTRY_PREFIX = "ksql.schema.registry.";
 
   public static final String SCHEMA_REGISTRY_URL_PROPERTY = "ksql.schema.registry.url";
@@ -496,8 +499,14 @@ private static ConfigDef buildConfigDef(final ConfigGeneration generation) {
             KSQL_INTERNAL_TOPIC_REPLICAS_PROPERTY,
             Type.SHORT,
             (short) 1,
-            ConfigDef.Importance.LOW,
+            ConfigDef.Importance.MEDIUM,
             "The replication factor for the internal topics of KSQL server."
+        ).define(
+            KSQL_INTERNAL_TOPIC_MIN_INSYNC_REPLICAS_PROPERTY,
+            Type.SHORT,
+            (short) 1,
+            ConfigDef.Importance.MEDIUM,
+            "The minimum number of insync replicas for the internal topics of KSQL server."
         ).define(
             KSQL_UDF_SECURITY_MANAGER_ENABLED,
             ConfigDef.Type.BOOLEAN,

ksql-rest-app/src/main/java/io/confluent/ksql/rest/server/CommandTopic.java

@@ -26,15 +26,10 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
-import java.util.concurrent.ExecutionException;
 import org.apache.kafka.clients.consumer.Consumer;
 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.ProducerRecord;
-import org.apache.kafka.clients.producer.RecordMetadata;
 import org.apache.kafka.common.TopicPartition;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -45,36 +40,28 @@ public class CommandTopic {
   private final TopicPartition commandTopicPartition;
 
   private Consumer<CommandId, Command> commandConsumer = null;
-  private Producer<CommandId, Command> commandProducer = null;
   private final String commandTopicName;
 
   public CommandTopic(
       final String commandTopicName,
-      final Map<String, Object> kafkaConsumerProperties,
-      final Map<String, Object> kafkaProducerProperties
+      final Map<String, Object> kafkaConsumerProperties
   ) {
     this(
         commandTopicName,
         new KafkaConsumer<>(
             Objects.requireNonNull(kafkaConsumerProperties, "kafkaClientProperties"),
             InternalTopicJsonSerdeUtil.getJsonDeserializer(CommandId.class, true),
             InternalTopicJsonSerdeUtil.getJsonDeserializer(Command.class, false)
-        ),
-        new KafkaProducer<>(
-            Objects.requireNonNull(kafkaProducerProperties, "kafkaClientProperties"),
-            InternalTopicJsonSerdeUtil.getJsonSerializer(true),
-            InternalTopicJsonSerdeUtil.getJsonSerializer(false)
-        ));
+        )
+    );
   }
 
   CommandTopic(
       final String commandTopicName,
-      final Consumer<CommandId, Command> commandConsumer,
-      final Producer<CommandId, Command> commandProducer
+      final Consumer<CommandId, Command> commandConsumer
   ) {
     this.commandTopicPartition = new TopicPartition(commandTopicName, 0);
     this.commandConsumer = Objects.requireNonNull(commandConsumer, "commandConsumer");
-    this.commandProducer = Objects.requireNonNull(commandProducer, "commandProducer");
     this.commandTopicName = Objects.requireNonNull(commandTopicName, "commandTopicName");
   }
 
@@ -86,24 +73,6 @@ public void start() {
     commandConsumer.assign(Collections.singleton(commandTopicPartition));
   }
 
-  public RecordMetadata send(final CommandId commandId, final Command command) {
-    final ProducerRecord<CommandId, Command> producerRecord = new ProducerRecord<>(
-        commandTopicName,
-        0,
-        Objects.requireNonNull(commandId, "commandId"),
-        Objects.requireNonNull(command, "command"));
-    try {
-      return commandProducer.send(producerRecord).get();
-    } catch (final ExecutionException e) {
-      if (e.getCause() instanceof RuntimeException) {
-        throw (RuntimeException)e.getCause();
-      }
-      throw new RuntimeException(e.getCause());
-    } catch (final InterruptedException e) {
-      throw new RuntimeException(e);
-    }
-  }
-
   public Iterable<ConsumerRecord<CommandId, Command>> getNewCommands(final Duration timeout) {
     return commandConsumer.poll(timeout);
   }
@@ -150,6 +119,5 @@ public void wakeup() {
 
   public void close() {
     commandConsumer.close();
-    commandProducer.close();
   }
 }

ksql-rest-app/src/main/java/io/confluent/ksql/rest/server/KsqlRestApplication.java

@@ -39,7 +39,9 @@
 import io.confluent.ksql.parser.KsqlParser.ParsedStatement;
 import io.confluent.ksql.parser.KsqlParser.PreparedStatement;
 import io.confluent.ksql.query.id.HybridQueryIdGenerator;
+import io.confluent.ksql.rest.entity.CommandId;
 import io.confluent.ksql.rest.entity.KsqlErrorMessage;
+import io.confluent.ksql.rest.server.computation.Command;
 import io.confluent.ksql.rest.server.computation.CommandQueue;
 import io.confluent.ksql.rest.server.computation.CommandRunner;
 import io.confluent.ksql.rest.server.computation.CommandStore;
@@ -72,7 +74,6 @@
 import io.confluent.ksql.services.ServiceContext;
 import io.confluent.ksql.statement.ConfiguredStatement;
 import io.confluent.ksql.util.KsqlConfig;
-import io.confluent.ksql.util.KsqlException;
 import io.confluent.ksql.util.RetryUtil;
 import io.confluent.ksql.util.Version;
 import io.confluent.ksql.util.WelcomeMsgUtils;
@@ -108,6 +109,10 @@
 import javax.websocket.server.ServerEndpointConfig.Configurator;
 import javax.ws.rs.core.Configurable;
 import org.apache.commons.lang3.StringUtils;
+import org.apache.kafka.clients.producer.Producer;
+import org.apache.kafka.common.errors.AuthorizationException;
+import org.apache.kafka.common.errors.OutOfOrderSequenceException;
+import org.apache.kafka.common.errors.ProducerFencedException;
 import org.apache.kafka.streams.StreamsConfig;
 import org.apache.log4j.LogManager;
 import org.eclipse.jetty.server.ServerConnector;
@@ -467,13 +472,16 @@ static KsqlRestApplication buildApplication(
 
     UserFunctionLoader.newInstance(ksqlConfig, functionRegistry, ksqlInstallDir).load();
 
-    final String commandTopic = KsqlInternalTopicUtils.getTopicName(
+    final String commandTopicName = KsqlInternalTopicUtils.getTopicName(
         ksqlConfig, KsqlRestConfig.COMMAND_TOPIC_SUFFIX);
 
     final CommandStore commandStore = CommandStore.Factory.create(
-        commandTopic,
+        commandTopicName,
+        ksqlConfig.getString(KsqlConfig.KSQL_SERVICE_ID_CONFIG),
+        Duration.ofMillis(restConfig.getLong(DISTRIBUTED_COMMAND_RESPONSE_TIMEOUT_MS_CONFIG)),
         restConfig.getCommandConsumerProperties(),
-        restConfig.getCommandProducerProperties());
+        restConfig.getCommandProducerProperties()
+    );
 
     final InteractiveStatementExecutor statementExecutor =
         new InteractiveStatementExecutor(serviceContext, ksqlEngine, hybridQueryIdGenerator);
@@ -501,19 +509,12 @@ static KsqlRestApplication buildApplication(
         authorizationValidator
     );
 
-    final KsqlResource ksqlResource = new KsqlResource(
-        ksqlEngine,
-        commandStore,
-        Duration.ofMillis(restConfig.getLong(DISTRIBUTED_COMMAND_RESPONSE_TIMEOUT_MS_CONFIG)),
-        versionChecker::updateLastRequestTime,
-        authorizationValidator
-    );
-
     final List<String> managedTopics = new LinkedList<>();
-    managedTopics.add(commandTopic);
+    managedTopics.add(commandTopicName);
     if (processingLogConfig.getBoolean(ProcessingLogConfig.TOPIC_AUTO_CREATE)) {
       managedTopics.add(ProcessingLogServerUtils.getTopicName(processingLogConfig, ksqlConfig));
     }
+
     final CommandRunner commandRunner = new CommandRunner(
         statementExecutor,
         commandStore,
@@ -522,6 +523,14 @@ static KsqlRestApplication buildApplication(
         serverState
     );
 
+    final KsqlResource ksqlResource = new KsqlResource(
+        ksqlEngine,
+        commandStore,
+        Duration.ofMillis(restConfig.getLong(DISTRIBUTED_COMMAND_RESPONSE_TIMEOUT_MS_CONFIG)),
+        versionChecker::updateLastRequestTime,
+        authorizationValidator
+    );
+
     final List<KsqlServerPrecondition> preconditions = restConfig.getConfiguredInstances(
         KsqlRestConfig.KSQL_SERVER_PRECONDITIONS,
         KsqlServerPrecondition.class
@@ -623,27 +632,47 @@ private static void maybeCreateProcessingLogStream(
       final KsqlEngine ksqlEngine,
       final CommandQueue commandQueue
   ) {
-    if (!config.getBoolean(ProcessingLogConfig.STREAM_AUTO_CREATE)
-        || !commandQueue.isEmpty()) {
+    if (!config.getBoolean(ProcessingLogConfig.STREAM_AUTO_CREATE)) {
       return;
     }
 
-    final PreparedStatement<?> statement = ProcessingLogServerUtils
-        .processingLogStreamCreateStatement(config, ksqlConfig);
-    final Supplier<ConfiguredStatement<?>> configured = () -> ConfiguredStatement.of(
-        statement, Collections.emptyMap(), ksqlConfig);
-
+    final Producer<CommandId, Command> transactionalProducer =
+        commandQueue.createTransactionalProducer();
     try {
+      transactionalProducer.initTransactions();
+      transactionalProducer.beginTransaction();
+
+      if (!commandQueue.isEmpty()) {
+        return;
+      }
+
+      // We don't wait for the commandRunner in this case since it hasn't been started yet.
+
+      final PreparedStatement<?> statement = ProcessingLogServerUtils
+          .processingLogStreamCreateStatement(config, ksqlConfig);
+      final Supplier<ConfiguredStatement<?>> configured = () -> ConfiguredStatement.of(
+          statement, Collections.emptyMap(), ksqlConfig);
+
       ksqlEngine.createSandbox(ksqlEngine.getServiceContext()).execute(
           ksqlEngine.getServiceContext(),
           configured.get()
       );
-    } catch (final KsqlException e) {
+
+      commandQueue.enqueueCommand(configured.get(), transactionalProducer);
+      transactionalProducer.commitTransaction();
+    } catch (final ProducerFencedException
+        | OutOfOrderSequenceException
+        | AuthorizationException e
+    ) {
+      // We can't recover from these exceptions, so our only option is close producer and exit.
+      // This catch doesn't abortTransaction() since doing that would throw another exception.
       log.warn("Failed to create processing log stream", e);
-      return;
+    } catch (final Exception e) {
+      transactionalProducer.abortTransaction();
+      log.warn("Failed to create processing log stream", e);
+    } finally {
+      transactionalProducer.close();
     }
-
-    commandQueue.enqueueCommand(configured.get());
   }
 
   /**

ksql-rest-app/src/main/java/io/confluent/ksql/rest/server/computation/CommandQueue.java

@@ -15,11 +15,13 @@
 
 package io.confluent.ksql.rest.server.computation;
 
+import io.confluent.ksql.rest.entity.CommandId;
 import io.confluent.ksql.statement.ConfiguredStatement;
 import java.io.Closeable;
 import java.time.Duration;
 import java.util.List;
 import java.util.concurrent.TimeoutException;
+import org.apache.kafka.clients.producer.Producer;
 
 /**
  * Represents a queue of {@link Command}s that must be distributed to all
@@ -34,13 +36,16 @@ public interface CommandQueue extends Closeable {
    * it is guaranteed that the command has been persisted, without regard
    * for the {@link io.confluent.ksql.rest.entity.CommandStatus CommandStatus}.
    *
-   * @param statement           The statement to be distributed
-   *
+   * @param statement              The statement to be distributed
+   * @param transactionalProducer  The transactional producer used to for enqueue the command
    * @return an asynchronous tracker that can be used to determine the current
    *         state of the command
    */
-  QueuedCommandStatus enqueueCommand(ConfiguredStatement<?> statement);
-
+  QueuedCommandStatus enqueueCommand(
+      ConfiguredStatement<?> statement,
+      Producer<CommandId, Command> transactionalProducer
+  );
+
   /**
    * Polls the Queue for any commands that have been enqueued since the last
    * invocation to this method.
@@ -74,6 +79,20 @@ public interface CommandQueue extends Closeable {
   void ensureConsumedPast(long seqNum, Duration timeout)
       throws InterruptedException, TimeoutException;
 
+  /**
+   * Creates a transactional producer for producing to the command topic.
+   *
+   * @return a TransactionalProducer
+   */
+  Producer<CommandId, Command> createTransactionalProducer();
+
+  /**
+   * Blocks until the command topic consumer has processed all records up to
+   * the current offset when this method is called.
+   *
+   */
+  void waitForCommandConsumer();
+
   /**
    * @return whether or not there are any enqueued commands
    */