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Improve pre-stop hook to avoid spurious logs #297

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Improve pre-stop hook to avoid spurious logs #297

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27 changes: 20 additions & 7 deletions templates/galera/bin/mysql_shutdown.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
# NOTE(dciabrin) we might use downward API to populate those in the future
PODNAME=$HOSTNAME
SERVICE=${PODNAME/-galera-[0-9]*/}
MYSQL_SOCKET=/var/lib/mysql/mysql.sock

# API server config
APISERVER=https://kubernetes.default.svc
Expand All @@ -24,6 +25,12 @@ else
exec &> >(cat >> /proc/1/fd/1) 2>&1
fi

# if the mysql socket is not available, mysql is either not started or
# not reachable, orchestration stops here.
if [ ! -e $MYSQL_SOCKET ]; then
exit 0
fi

# On update, k8s performs a rolling restart, but on resource deletion,
# all pods are deleted concurrently due to the fact that we require
# PodManagementPolicy: appsv1.ParallelPodManagement for bootstrapping
Expand All @@ -44,16 +51,22 @@ if curl -s --cacert ${CACERT} --header "Content-Type:application/json" --header
done
fi

log "Initiating orchestrated shutdown of the local galera node"

log "Failover service to another available galera node"
bash $(dirname $0)/mysql_wsrep_notify.sh --status failover
# We now to need disconnect the clients so that when the server will
# initiate its shutdown, they won't receive unexpected WSREP statuses
# when running SQL queries.
# Note: It is safe to do it now, as k8s already removed this pod from
# the service endpoint, so client won't reconnect to it.

log "Close all active connections to this local galera node"
# filter out system and localhost connections, only consider clients with a port in the host field
# from that point, clients will automatically reconnect to another node
CLIENTS=$(mysql -uroot -p${DB_ROOT_PASSWORD} -nN -e "select id from information_schema.processlist where host like '%:%';")
echo -n "$CLIENTS" | tr '\n' ',' | xargs mysqladmin -uroot -p${DB_ROOT_PASSWORD} kill
echo -n "$CLIENTS" | tr '\n' ',' | xargs -r mysqladmin -uroot -p${DB_ROOT_PASSWORD} kill

# At this point no clients are connected anymore.
# We can finish this pre-stop hook and let k8s send the SIGTERM to the
# mysql server to make it disconnect from the galera cluster and shut down.
# Note: shutting down mysql here would cause the pod to finish too early,
# and this pre-stop hook would shows up as 'Failed' in k8s events.

log "Shutdown local server"
mysqladmin -uroot -p"${DB_ROOT_PASSWORD}" shutdown
exit 0
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