Just tagged images of logstash for docker, nothing else.
It is build from official java images and official
logstash distribution, you can make you image FROM this one.
For testing you may supply config via cli args:
docker run --rm -it bobrik/logstash:1.4.2 -e 'input { stdin { } } output { stdout { codec => rubydebug } }'
But to run with custom config you should bind-mount it from host:
docker run --rm -it -v /tmp/logstash.conf:/etc/logstash/logstash.conf bobrik/logstash:1.4.2
Note that it takes some time for logstash to start up and shut down.
See logstash-kafka to see an example of extended image with kafka plugin installed.