The purpose of this image is to generate HAProxy config using Marathon as a data source and storing the resulting config in ZooKeeper. This allows a dedicated container to run haproxy, monitor ZooKeeper for config changes and reload haproxy when config has been updated.
See https://github.com/mesoscloud/haproxy
e.g.
docker run -d \
-e MARATHON=node-1:8080 \
-e ZK=node-1:2181 \
--name=haproxy --net=host --restart=always mesoscloud/haproxy-marathon:0.2.1