We'll be upgrading the cloud services OpenStack install on Monday, beginning at 14:00 UTC.
The entire upgrade process may take a couple of hours. Early on in the process, Horizon (and associated OpenStack APIs) will be disabled (probably for 20 to 30 minutes.) There may also be brief network interruptions during the upgrade, although if all goes well these will not be noticeable by users.
Toolforge and existing VMs should be largely unaffected apart from possible network hiccups.
- Andrew + the WMCS team