Port existing feature from MapReduceIndexerTool:
Record fields can be passed from the CLI and indexer definition config file to the Morphline, e.g.
     * <param name="morphlineField._attachment_mimetype" value="text/csv"
or
hadoop … -DmorphlineField._attachment_mimetype=text/csv

Likewise, morphline variables can be passed from the CLI or indexer definition config file to the Morphline, e.g.:

hadoop ... -D morphlineVariable.zkHost=127.0.0.1:2181/solr
or
<param name="morphlineVariable.zkHost" value="127.0.0.1:2181/solr"/>