Comment 6 for bug 1442308

We have seen this in the wild on Trusty when a container hangs trying to shutdown. We think that case was because of I/O blocking preventing the container from shutting down for more than 5 minutes.

There are other possibilities where we're using the init system (upstart vs systemd) to issue the cleanup and shutdown commands, rather than just running them at the end of cloud-init. I'm not sure why we need a service to shutdown cleanly.