Current revert instructions
See https://wikitech.wikimedia.org/wiki/Dbctl#Emergency_revert_to_static_configs
Background
dbctl is a tool based on conftool that stores Mediawiki's database loadbalancer configuration in etcd. This ticket tracks its rollout to WMF production.
Rollout planned to begin on Tuesday 30 July.
Rollout should last only one week, as for the duration of the rollout, DBAs will need to perform the extra toil of modifying the database configuration in both mediawiki-config as well as in dbctl.
Proposed rollout plan:
The week of 30 July and the week of 5 August are Americas Mediawiki train weeks, so on each day, this rollout will be timed to finish well before the train begins.
The set of hosts using dbctl is controlled by the array $dbctl_enabled_hosts in CommonSettings.php.
For the first two days of the rollout, the quickest way to revert will be to depool the small number of appservers involved.
If a revert is needed after Thursday, it would be wiser to perform a mediawiki-config change that removes entries from $dbctl_enabled_hosts instead.
Tuesday 30 July:
- mwdebug1001
- mwdebug*
- mw1261 (a single canary appserver)
- mw1276 (a single canary apiserver)
- all canary appservers, apiservers, jobrunners
Wednesday:
- 25% of appservers and apiservers and jobrunners
Thursday:
- 100% of appservers and apiservers and jobrunners