Databases on m5:

labsdbaccounts
mailman3
mailman3web
striker
test_labsdbaccounts
toolhub

Impact: Writes will be disabled for around 1 minute.

Failover process

OLD MASTER: db1119

NEW MASTER: db1176

• Check configuration differences between new and old master

$ pt-config-diff h=db1176.eqiad.wmnet,F=/root/.my.cnf h=db1119.eqiad.wmnet,F=/root/.my.cnf

• Silence alerts on all hosts: sudo cookbook sre.hosts.downtime --minutes 60 -r "m5 master switch T352631" 'A:db-section-m5'
• Topology changes: move everything under db1176

db-switchover --timeout=15 --only-slave-move db1119.eqiad.wmnet db1176.eqiad.wmnet

• Disable puppet db1176 and db1119 sudo cumin 'db1176* or db1119*' 'disable-puppet "primary switchover T352631"'
• Merge gerrit: https://gerrit.wikimedia.org/r/c/operations/puppet/+/979695
• Run puppet on dbproxy1027 and dbproxy1021 and check the config

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

• Start the failover: !log Failover m5 from db1119 to db1176 - T352631
• DB switchover

root@cumin1001:~/wmfmariadbpy/wmfmariadbpy# db-switchover --skip-slave-move db1119 db1176

• Reload haproxies (dbproxy1021 is the active one)

dbproxy1017:   systemctl reload haproxy && echo "show stat" | socat /run/haproxy/haproxy.sock stdio
dbproxy1021:   systemctl reload haproxy && echo "show stat" | socat /run/haproxy/haproxy.sock stdio

• kill connections on the old master (db1119)

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):db1176 and db1119 sudo cumin 'db1176* or db1119*' 'run-puppet-agent -e "primary switchover T352631"'
• Check affected services
• Clean orchestrator heartbeat to remove the old masters' one, otherwise Orchestrator will show lag: delete from heartbeat where server_id= 171970573;