Issue #1273: Deal with unavailable Kafka broker in KafkaPublisherActor.

Until now a Ditto Kafka connection with targets only did not cope properly with the Kafka broker becoming unavailable.
In such cases, publishing timed out and produced appropriate entries in connection log.
Connection live status however, remained always 'open'.
With this commit, a TimeoutException while publishing is handled in a way that a ConnectionFailure is propagated to parent BaseClientActor.
This sets connection live status to 'misconfigured' and triggers reconnect with back-off semantic.
Thus, a potentially unavailable Kafka broker gets appropriately reflected by connection status.

Signed-off-by: Juergen Fickel <juergen.fickel@bosch.io>

connectivity/service/src/main/java/org/eclipse/ditto/connectivity/service/messaging/kafka/KafkaPublisherActor.java

@@ -15,6 +15,7 @@
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
+import java.time.Instant;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
@@ -53,6 +54,7 @@
 import org.eclipse.ditto.connectivity.service.messaging.ConnectivityStatusResolver;
 import org.eclipse.ditto.connectivity.service.messaging.ExceptionToAcknowledgementConverter;
 import org.eclipse.ditto.connectivity.service.messaging.SendResult;
+import org.eclipse.ditto.connectivity.service.messaging.internal.ConnectionFailure;
 import org.eclipse.ditto.json.JsonField;
 import org.eclipse.ditto.json.JsonObject;
 import org.eclipse.ditto.json.JsonObjectBuilder;
@@ -181,6 +183,18 @@ protected CompletionStage<SendResult> publishMessage(final Signal<?> signal,
                 .withHeader("ditto-connection-id", connection.getId().toString());
 
         return producerStream.publish(publishTarget, messageWithConnectionIdHeader)
+                .whenComplete((recordMetadata, throwable) -> {
+                    if (null != throwable) {
+                        final var context = getContext();
+                        final var parent = context.getParent();
+                        final var self = getSelf();
+                        parent.tell(ConnectionFailure.of(self,
+                                throwable,
+                                ConnectionFailure.determineFailureDescription(Instant.now(),
+                                        throwable,
+                                        "Broker may not be available.")), self);
+                    }
+                })
                 .thenApply(callback);
     }
 

connectivity/service/src/main/resources/connectivity.conf

@@ -20,8 +20,9 @@ ditto {
       # Kafka
       {exceptionName: "org.apache.kafka.common.errors.SaslAuthenticationException", messagePattern: ".*"}
       {exceptionName: "org.apache.kafka.common.errors.UnsupportedSaslMechanismException", messagePattern: ".*"}
-      {exceptionName: "org.apache.kafka.common.errors.IllegalSaslStateException", messagePattern: ".*"},
+      {exceptionName: "org.apache.kafka.common.errors.IllegalSaslStateException", messagePattern: ".*"}
       {exceptionName: "org.apache.kafka.common.errors.SslAuthenticationException", messagePattern: ".*"}
+      {exceptionName: "org.apache.kafka.common.errors.TimeoutException", messagePattern: ".*"}
       # MQTT
       {exceptionName: "com.hivemq.client.mqtt.exceptions.ConnectionClosedException", messagePattern: "Server closed connection without DISCONNECT.*"}
       {exceptionName: "com.hivemq.client.mqtt.exceptions.ConnectionClosedException", messagePattern: "io.netty.channel.unix.Errors$NativeIoException.*"}