https://github.com/docker/libnetwork/pull/810 provides the more complete solution for moving the Port-mapping ownership away from endpoint and into Sandbox. But, this PR makes the best use of existing libnetwork design and get a step closer to the gaol. Signed-off-by: Madhu Venugopal <madhu@docker.com> Upstream-commit: e38463b2779f455b4173171d5a1fdb115180a7e9 Component: engine