elasticsearch/logstash — pull request #1286 by nfelsen (2014-04-17 20:49:38+00:00)
Title: Making the -f option multivalued

Changing the flag -f to be multivalued. It's super useful when you want to package custom logstash configurations with your services

example:
bin/logstash -f '/etc/logstash/conf.d/*' -f '/services/*/logstash/conf.d/*'