I am working on a project that will require two Robot Operating System (ROS) nodes running in separate containers on separate hosts on separate LANs to communicate over a router. The issue I am having is that ROS uses XMLRPC to open up a dynamic ephemeral port on the host to establish a socket connection between publisher & subscriber nodes. The Docker container that each of the ROS nodes run in has a local port range in the proc/sys/net/ipv4/ip_local_port_range from 32768-60999. I will need to bind the container port to the local host port in order for the two ROS nodes to communicate. Unfortunately, this will require that I bind 28231 ports at docker run command in order to ensure that ROS dynamically chooses an exposed and binded port to communicate over the network. I would like to limit the ephemeral port range to 1000 ports in the docker container to allow for efficient use of ROS and docker, especially when quickly spinning up new containers for high availability. Below are what I have done thus far:
run docker swarm on each of the hosts to communicate over the docker overlay bridge
in Dockerfile–EXPOSE 32768-33768
bind to host–docker run -it --rm -p 32768-33768:32768-33768
looking in the proc/sys/net/ipv4/ip_local_port_range the ephemeral port range is read only from 32768-60999
I am running ubuntu 14.04 LTS, Docker v1.12, ROS Indigo Base
Any help in limiting the ephemeral port range to a known range from 32768-33768 would be greatly appreciated. Thank you