Are you running Rancher in Docker container then, or did you install it directly on Centos ?
Wondering if it would be the way to go to run it in Docker, now that Docker support is being deprecated, if I am understanding it right.
Rancher plain on centos with docker run.
It is an easy and painless way to use the complex setup of kubernetes.
Another solution may be to use a redhat developer account and play around with openshift to compare different solutions.