Sometime soon we need to upgrade our OpenStack deployment to the next release, 'Mitaka'.  I've done a test upgrade and the process was fairly smooth, but there is at least one step that will cause unavoidable downtime for new instance creation. Ideally this will only take around 20 minutes, but given the number of surprises I ran into just now it wouldn't shock me if it winds up taking several hours instead.     I propose to do this upgrade starting at the beginning of my day on next Friday, April 13th.  Unlucky number, but being a Friday there are no active MediaWiki deployments so the lack of CI should be less disruptive than usual.  The next day is largely unscheduled for me, and the following Monday is a WMF holiday so that gives us an entire four-day block to back out any possible disasters before we're really stepping on release engineering's toes.     The upgrade should not interfere with existing VMs.  If there are no objections, I'll send a public announcement about this tomorrow. -Andrew