Impact: Read only for a few seconds on the services below:

Services running on m1:

• bacula
• cas (and cas staging)
• backups
• etherpad
• librenms
• pki
• rt

Switchover steps:

OLD MASTER: db1164

NEW MASTER: db1213

• Check configuration differences between new and old master pt-config-diff h=db1213.eqiad.wmnet,F=/root/.my.cnf h=db1164.eqiad.wmnet,F=/root/.my.cnf
• Enable notifications on db1213
• Silence alerts on all hosts: sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover m1 T434493" 'A:db-section-m1'
• Topology changes: move everything under db1213

sudo db-switchover --timeout=1 --only-slave-move db1164.eqiad.wmnet db1213.eqiad.wmnet

• Disable puppet @db1164 and puppet @db1213 sudo cumin 'db1213* or db1164*' 'disable-puppet "primary switchover T434493"'
• Merge gerrit: https://gerrit.wikimedia.org/r/c/operations/puppet/+/1324271
• Run puppet on dbproxy1022 and dbproxy1024 and check the config

run-puppet-agent && cat /etc/haproxy/conf.d/db-master.cfg

• Start the failover

!log Failover m1 from db1164 to db1213 - T434493

root@cumin1001:~/wmfmariadbpy/wmfmariadbpy# sudo db-switchover --skip-slave-move db1164 db1213

• Reload haproxies

dbproxy1022:   systemctl reload haproxy && echo "show stat" | socat /run/haproxy/haproxy.sock stdio
dbproxy1024:   systemctl reload haproxy && echo "show stat" | socat /run/haproxy/haproxy.sock stdio

• kill connections on the old master (db1164)

pt-kill --print --kill --victims all --match-all F=/dev/null,S=/run/mysqld/mysqld.sock

• Restart puppet on old and new masters (for heartbeat):db1164 and db1213

sudo cumin 'db1213* or db1164*' 'run-puppet-agent -e "primary switchover T434493"'

• Check services affected (librenms, racktables, etherpad...)
• Clean orchestrator heartbeat to remove the old masters' one: sudo db-mysql db1213 heartbeat -e "delete from heartbeat where file like 'db1164%';"
• Merge backup ticket: https://gerrit.wikimedia.org/r/c/operations/puppet/+/1324263
• Update/resolve phabricator ticket about failover