I’ve upgraded my old ML115 ESX box to Ubuntu 16.04, using OpenNebula as the virtualization platform. ON is available in the system repos, but this is an old version (4.1) so I’d advise using the ON repos. OpenNebula provides an EC2-compatible API, which allows the use of libcloud and there is also Docker integration.

Ubuntu 16.04 also allows me to investigate ZFS and SystemD (systemd-networkd makes configuring the bridging interface required for OpenNebula very easy).