title: Apache kafka : broker leader -1 (topic received from Orion via Cygnus)
body: <p>I'm working with Apache Kafka and receiving topics from Orion Context Broker via Cygnus (Fiware Labs)</p>
  
  <p>I'm receiving 10 topics, and I can see data arriving in the consumer console for 8 topics. </p>
  
  <p>But for 2 others topics, I cannot see any data arriving. And there is no error code (the consumer is just empty). If i try to add a test line to the topic via the producer console, i get this error:</p>
  
  <pre><code>ERROR Error when sending message to topic sensors_presence2_sensors with key: null, value: 4 bytes with error: Batch Expired (org.apache.kafka.clients.producer.internals.ErrorLoggingCallback)
  </code></pre>
  
  <p>So I used the describe command and I get this : </p>
  
  <pre><code>Topic:sensors_presence2_sensors PartitionCount:1    ReplicationFactor:1 Configs:
  Topic: sensors_presence2_sensors    Partition: 0    Leader: -1  Replicas: 2 Isr: 
  </code></pre>
  
  <p>I'm just starting with Kafka, so for the moment I have 1 broker(0) and no partition. But why is my leader -1 ? This broker do not even exist. How can I change that ? I didn't choose the configuration for my topic, they arrived automatically from Cygnus (Orion Context Broker) with a OrionKafkaSink. </p>
  
  <p>An example of one of the 8 topics that works well : </p>
  
  <pre><code>Topic:sensors_presence1_sensors PartitionCount:1    ReplicationFactor:1 Configs:
  Topic:sensors_presence1_sensors Partition: 0    Leader: 0   Replicas: 0 Isr: 0
  </code></pre>
  
  <p>Thanks</p>
  
  <p>Edit : In Cygnus logs, it shows that data is correctly send to kafka : </p>
  
  <pre><code>time=2016-03-02T11:07:09.504UTC | lvl=INFO | trans=1456915468-194-0000000039 | srv=egmmqtt | subsrv=egmmqttpath | function=persistAggregation | comp=Cygnus | msg=com.telefonica.iot.cygnus.sinks.OrionKafkaSink[279] : [kafka-sink] Persisting data at OrionKafkaSink. Topic (sensors_presence2_sensors), Data (...
  </code></pre>