title: Kafka elasticsearch connector - 'Flush timeout expired with unflushed records:'
body: <p>I have a strange problem with kafka -> elasticsearch connector. First time when I started it all was great, I received a new data in elasticsearch and checked it through kibana dashboard, but when I produced new data in to kafka using the same producer application and tried to start connector one more time, I didn't get any new data in elasticsearch.
  Now I'm getting such errors:</p>
  
  <pre><code>[2018-02-04 21:38:04,987] ERROR WorkerSinkTask{id=log-platform-elastic-0} Commit of offsets threw an unexpected exception for sequence number 14: null (org.apache.kafka.connect.runtime.WorkerSinkTask:233)
  org.apache.kafka.connect.errors.ConnectException: Flush timeout expired with unflushed records: 15805
  </code></pre>
  
  <p>I'm using next command to run connector:</p>
  
  <pre><code>/usr/bin/connect-standalone /etc/schema-registry/connect-avro-standalone.properties log-platform-elastic.properties
  </code></pre>
  
  <p><strong>connect-avro-standalone.properties</strong>:</p>
  
  <pre><code>bootstrap.servers=kafka-0.kafka-hs:9093,kafka-1.kafka-hs:9093,kafka-2.kafka-hs:9093
  key.converter=io.confluent.connect.avro.AvroConverter
  key.converter.schema.registry.url=http://localhost:8081
  value.converter=io.confluent.connect.avro.AvroConverter
  value.converter.schema.registry.url=http://localhost:8081
  internal.key.converter=org.apache.kafka.connect.json.JsonConverter
  internal.value.converter=org.apache.kafka.connect.json.JsonConverter
  internal.key.converter.schemas.enable=false
  internal.value.converter.schemas.enable=false
  offset.storage.file.filename=/tmp/connect.offsets
  # producer.interceptor.classes=io.confluent.monitoring.clients.interceptor.MonitoringProducerInterceptor
  # consumer.interceptor.classes=io.confluent.monitoring.clients.interceptor.MonitoringConsumerInterceptor
  #rest.host.name=
  rest.port=8084
  #rest.advertised.host.name=
  #rest.advertised.port=
  plugin.path=/usr/share/java
  </code></pre>
  
  <p>and <strong>log-platform-elastic.properties</strong>:</p>
  
  <pre><code>name=log-platform-elastic
  key.converter=org.apache.kafka.connect.storage.StringConverter
  connector.class=io.confluent.connect.elasticsearch.ElasticsearchSinkConnector
  tasks.max=1
  topics=member_sync_log, order_history_sync_log # ... and many others
  key.ignore=true
  connection.url=http://elasticsearch:9200
  type.name=log
  </code></pre>
  
  <p>I checked connection to kafka brokers, elasticsearch and schema-registry(schema-registry and connector are on the same host at this moment) and all is fine. Kafka brokers are running on port 9093 and I'm able to read data from topics using kafka-avro-console-consumer.
  I'll be gratefull for any help on this!</p>