
A really simple version of this was in container sync already, and I needed a more complete version for work I'm doing, and I noticed https://review.openstack.org/#/c/33405/ was also making use of it. So, here's a more full version. If https://review.openstack.org/#/c/33405/ lands before this, I'll update it accordingly. Change-Id: Iba66b6a97f65e312e04fdba273e8f4ad1d3e1594