Reposting from Docker:
On August 25th at 11am PT (Saturday), Docker will be performing major infrastructure upgrades to Docker Hub, Docker Store, and Docker Cloud. It is anticipated that this upgrade will take between 15 and 45 minutes to perform.
The database version used by these services is being upgraded. This allows us to pick up performance improvements that will result in a better user experience.
All services on Docker Hub, Store, and Cloud will be unavailable during the upgrade. This means you will not be able to pull or push images to Docker Hub, use the web UI for Hub, Store, and Cloud, or log into any web properties that uses hub.docker.com or id.docker.com for login (for example, support.docker.com and forums.docker.com).
In the event that Docker technical support is needed, Docker Enterprise Edition customers can call +1-888-214-4258 (toll-free in the USA) or +1-204-285-0350 (outside the USA) during the outage.
We have added this scheduled downtime to our Statuspage, as well: