D1G is live on the new infra, thanks a lot everyone :).
The actual migration took a bit less than 10 minutes.
Also special thanks for the list rrq, it was very useful; it went down a
bit differently, here it is for posterity:
1. Preparation
* Added /etc/nginx/sites-enabled/placeholder
* in backup script:
* rm /etc/nginx/sites-enabled/default
* service nginx restart
--> result is: after the backup, page is offline and placeholder
in-place (hopefully)
* This goes down at 19.00 UTC
* on new nginx:
galaxy.devuan.org / www.dev1galaxy.org redir to dev1galaxy.org
* Forum only served at dev1galaxy.org
2. Actual migration
* At 18.00 UTC we changed TTL down from 30 min to 5 min
* At 19.00 UTC, after backup script runs (and page is locked):
* transfer the 2017-08-10 backup to new site
* DB restore
* open the new site for changes
* (X) iptables rules
* (X) test with local hosts file
* Change A records to 91.134.216.234
* Increment TTL
3. with until DNS has taken effect (5Min * 2 = 10 Mins tops)
4. got to old server and block all tcp except 22 turn off services.
--
Evilham