diff --git a/systemd-units/mariadbontmpfs.service b/systemd-units/mariadbontmpfs.service new file mode 100644 index 0000000..7ecbf23 --- /dev/null +++ b/systemd-units/mariadbontmpfs.service @@ -0,0 +1,72 @@ +# This systemd unit puts the MariaDB/MySQL storage on tmpfs and (tries to) sync +# it back at shutdown. + +# Of course, in case of power failure or any problem preventing this +# unit to stop properly and sync back the data to disk : DATA LOSS. + +# To install : +# - apt install rsync +# - systemctl stop mariadb +# - copy this file to /etc/systemd/system/mariadbontmpfs.service +# - systemctl enable mariadbontmpfs.service +# - systemctl start mariadbontmpfs.service +# - systemctl start mariadb + +# This file is free software licensed under the WTFPL (v2) +# DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE +# Version 2, December 2004 +# +# Copyright (C) 2004 Sam Hocevar +# +# Everyone is permitted to copy and distribute verbatim or modified +# copies of this license document, and changing it is allowed as long +# as the name is changed. +# +# DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE +# TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION +# +# 0. You just DO WHAT THE FUCK YOU WANT TO. + +[Unit] +Description=Put /var/lib/mysql on tmpfs before MariaDB/MySQL starts +Before=mariadb.service mysql.service +ConditionPathIsDirectory=/var/lib/mysql +ConditionPathExists=/usr/bin/rsync + + +[Install] +WantedBy=multi-user.target + + +[Service] +Type=oneshot +RemainAfterExit=yes +Restart=no + +# We double-check that MariaDB is not running before doing anything +# Per https://www.freedesktop.org/software/systemd/man/systemd.service.html +# when an ExecCondition= command exits with exit code 1 through 254 +# (inclusive), the remaining commands are skipped and the unit is not marked as +# failed. However, if an ExecCondition= command exits with 255 or abnormally +# (e.g. timeout, killed by a signal, etc.), the unit will be considered failed +# (and remaining commands will be skipped). +ExecCondition=/bin/sh -c "systemctl --quiet is-active mariadb mysql && echo 'MariaDB or MySQL still active' && exit 255 || exit 0" + +# If the ON-DISK directory doesn't exist, simply rename /var/lib/mysql to +# /var/lib/mysql.ON-DISK and recreate /var/lib/mysql +ExecStart=/bin/sh -c "if [ ! -e /var/lib/mysql.ON-DISK ] ; then mv -v /var/lib/mysql /var/lib/mysql.ON-DISK && mkdir -v /var/lib/mysql && chown -v mysql:mysql /var/lib/mysql; fi" +# Mount the tmpfs +# (note: to forcefully limit memory consumption, we can add 'size=1024M' to the mount options) +ExecStart=/bin/mount -v -t tmpfs -o uid=mysql,gid=mysql,mode=0755 none /var/lib/mysql +# Copy the ON-DISK content to the tmpfs +ExecStart=/usr/bin/rsync -avH --delete /var/lib/mysql.ON-DISK/ /var/lib/mysql/ + +# At stop : +# - Little notice for the logs +ExecStop=/bin/sh -c "echo 'Syncing tmpfs:/var/lib/mysql to disk'" +# - fetch back the in-memory data to disk +ExecStop=/usr/bin/rsync -avH --delete /var/lib/mysql/ /var/lib/mysql.ON-DISK/ +# - destroy the tmpfs +ExecStop=/bin/umount -v /var/lib/mysql +# - put back the on-disk storage in its original path +ExecStop=/bin/sh -c "rmdir -v /var/lib/mysql && mv -v /var/lib/mysql.ON-DISK /var/lib/mysql"