spark 怎么去连接 ElasticSearch

https://stackoverflow.com/questions/52659109/cannot-read-from-elasticsearch-using-pyspark
https://stackoverflow.com/questions/35982550/how-to-read-data-from-elasticsearch-to-spark
https://stackoverflow.com/questions/38162901/how-to-query-an-elasticsearch-index-using-pyspark-and-dataframes/38191995