As part of upgrading s5 to debian buster/mariadb 10.4, we need to switch the master to be db1130
When: Tuesday 22nd June at 05:00 AM UTC
Checklist:
- Double check db1130 has report_host enabled T271106
- Create a task to communicate the chosen date and send an announcement to the community: T284530
NEW master: db1130
OLD master: db1100
- Check configuration differences between new and old master:
sudo pt-config-diff h=db1130.eqiad.wmnet,F=/root/.my.cnf h=db1100.eqiad.wmnet,F=/root/.my.cnf
Failover prep:
- Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Master switchover s5 T284529" 'A:db-section-s5'
- Set NEW master with weight 0
sudo dbctl instance db1130 set-weight 0 sudo dbctl config commit -m "Set db1130 with weight 0 T284529"
- Topology changes, move all replicas under NEW master
sudo db-switchover --timeout=15 --only-slave-move db1100.eqiad.wmnet db1130.eqiad.wmnet
- Disable puppet on both nodes
sudo cumin 'db1100* or db1130*' 'disable-puppet "master switchover T284529"'
- Merge gerrit puppet change to promote NEW master: https://gerrit.wikimedia.org/r/700462
Failover:
- Log the failover:
!log Starting s5 eqiad failover from db1100 to db1130 - T284529
- Set section read-only:
sudo dbctl --scope eqiad section s5 ro "Maintenance until 05:15 UTC - T284529" sudo dbctl config commit -m "Set s5 eqiad as read-only for maintenance - T284529"
- Check s5 is indeed read-only
- Switch masters:
sudo db-switchover --skip-slave-move db1100 db1130 echo "===== db1100 (OLD)"; sudo mysql.py -h db1100 -e 'show slave status\G' echo "===== db1130 (NEW)"; sudo mysql.py -h db1130 -e 'show slave status\G'
- Promote NEW master in dbctl, and remove read-only
sudo dbctl --scope eqiad section s5 set-master db1130 sudo dbctl --scope eqiad section s5 rw sudo dbctl config commit -m "Promote db1130 to s5 master and set section read-write T284529"
- Restart puppet on both hosts (for heartbeat):
sudo cumin 'db1130* or db1100*' 'run-puppet-agent -e "master switchover T284529"'
Clean up tasks:
- change events for query killer:
events_coredb_master.sql on the new master db1130 events_coredb_slave.sql on the new slave db1100
- Update DNS: https://gerrit.wikimedia.org/r/c/operations/dns/+/699136/
- Update candidate master dbctl notes
sudo dbctl instance db1100 set-candidate-master --section s5 true sudo dbctl instance db1130 set-candidate-master --section s5 false
- Check tendril was updated
- Check zarcillo was updated
- Depool OLD master, as it's running 10.1, replicating from a 10.4 master
sudo dbctl instance db1100 depool sudo dbctl config commit -m "Depool db1100 until it's reimaged to buster T284529"