Logstash config


I played with the ELK version of Devilbox. It works fine so far. Now I want to configure logstash to connect to my external mysql db. My question is:

Where can I find the logstash.conf file or how can I mount the /config folder from the logstash container?

I tried this (but had no luck):

      - ${DEVILBOX_PATH}/cfg/logstash:/config:ro${MOUNT_OPTIONS}

Thanks for your help.