MariaDB Backup Scrip to be run on Synology NAS

mariabackup

#!/usr/bin/env bash
# ******************************************************************************
# MariaDB Backup Scrip to be run on Synology NAS
# (MariaDB 10.3.29-1038 package published by Synology Inc.)
#
# * Full online physical backups with mariabackup:
#  - no databse downtime (as with physical copy or HyperBackup)
#  - database caches are not affected (as with SQL-dumps)
# * Ensure only one single instance is running at same time
# * Ensure at least one successful full backup is present at all times
#
# See https://mariadb.com/kb/en/mariabackup-overview/
#
# Prerequisites:
#   ln -s /volume1/@appstore/MariaDB10/usr/local/mariadb10/bin/mariabackup \
#       /usr/local/bin/
#
#   CREATE USER 'mariabackup'@'localhost' IDENTIFIED BY 'change_me';
#   GRANT RELOAD, PROCESS, LOCK TABLES, REPLICATION CLIENT ON *.* \
#       TO 'mariabackup'@'localhost';
#   GRANT CREATE ON PERCONA_SCHEMA.* TO 'mariabackup'@'localhost';
#   FLUSH PRIVILEGES;
#
#   Make sure app-data backup for MariaSB in HyperBackup is disabled!
#   Make sure your backup-root directory is included by HyperBackup!
#
# ******************************************************************************

# ---------------------------------------
# Settings
# ---------------------------------------
_BACKUP_ROOT="/var/services/homes/admin/mariabackup"
_SYSTEM_USER="mysql"
_DATABASE_USER="mariabackup"
_DATABASE_PASSWORD="change_me"
# ---------------------------------------

# Abort on any error or undefined variable
set -e -u

_lock_file="/tmp/mariabackup.lock"
_log="${_BACKUP_ROOT}/mariabackup.log"
_error_log="${_BACKUP_ROOT}/mariabackup.err"
_success_file="completed.ok"
_full_1="${_BACKUP_ROOT}/full-1"
_full_2="${_BACKUP_ROOT}/full-2"

# Am I the one?
if [[ $( whoami ) != "$_SYSTEM_USER" ]]; then
    printf "This script is supposed to run by the \"%s\" user!\nAborting!\n" \
        $_SYSTEM_USER
    exit 1
fi

# ---------------------------------------
# Lock-file
# ---------------------------------------

# Redirect file descriptor 100 to our lock file until end of this script,
# or exit with error if that fails (because its locked by another process).
if ! exec 100>$_lock_file ; then
    printf "Redirection to %s failed!\nIs another instance running?\n" $_lock_file
    exit 1
fi

# Obtain a lock on our redirected file descriptor 100
# or exit immediately with error if no lock can be obtained.
if ! flock -n 100 ; then
    printf "Obtaining lock on fd failed!\nIs another instance running?\n"
    exit 1
fi


# ---------------------------------------
# Look for previous successfull backups
# ---------------------------------------

# Look for full-1
if [ -f "${_full_1}/${_success_file}" ]; then
    printf "File \"%s\" exists.\n" "${_full_1}/${_success_file}"
else

    # Not found or presumably not complete: delete this dirctory!
    rm -rf "$_full_1"

    # We will backup to full-1
    _target_dir=$_full_1
fi

# Look for full-2
if [ -f "${_full_2}/${_success_file}" ]; then
    printf "File \"%s\" exists\n" "${_full_2}/${_success_file}"
else

    # Not found or presumably not complete: delete this dirctory!
    rm -rf "$_full_2"

    # We will backup to full-2
    _target_dir=$_full_2
fi

# ---------------------------------------
# Delete older one of the two
# ---------------------------------------

# Is this one is older as the other
if [ "$_full_1" -ot "$_full_2" ]; then

    # Delete older directory
    rm -rf "$_full_1"

    # We will backup to full-1
    _target_dir=$_full_1
else

    # Delete older directory
    rm -rf "$_full_2"

    # We will backup to full-2
    _target_dir=$_full_2
fi

# ---------------------------------------
# Do the backup
# ---------------------------------------
printf "Starting MariaDB Backup to %s ...\n"  $_target_dir
mariabackup --backup --target-dir="${_target_dir}" \
    --user=${_DATABASE_USER} --password=${_DATABASE_PASSWORD} \
    > "$_log" 2> "$_error_log"
printf "MariaDB Backup completed to.%s \n" $_target_dir \
    tee "${_target_dir}/${_success_file}"

# -*- mode: bash; indent-tabs-mode: nil; tab-width: 4; -*-