in flume-elasticsearch-sink/src/main/java/org/apache/flume/sink/elasticsearch/client/ElasticSearchTransportClient.java [215:222]
private void openLocalDiscoveryClient() {
logger.info("Using ElasticSearch AutoDiscovery mode");
Node node = NodeBuilder.nodeBuilder().client(true).local(true).node();
if (client != null) {
client.close();
}
client = node.client();
}