Floating IP for containers in a Swarm

Please be gentle as I’m just a Sysadmin and new to Docker.
I have used “containers” Zones in the Solaris world with Sun clustering and now I need to implement a Docker container that can run on 2 hosts and have the same Internet facing IP address nor matter which host it is running on.
I have looked at implementing with HA Proxy but have yet to make it work.

Running Docker version 17.03.0-ce, build 3a232c8 on Debian 3.16.39-1+deb8u2.

To me, this should be a rather simple task, but I have yet to find a cookbook on how to implement it.

Has anyone here done something similar or know of a how to somewhere?