MariaDB database backup and restore¶
Kolla Ansible can facilitate either full or incremental backups of data hosted in MariaDB. It achieves this using Mariabackup, a tool designed to allow for ‘hot backups’ - an approach which means that consistent backups can be taken without any downtime for your database or your cloud.
By default, backups will be performed on the first node in your Galera cluster
or on the MariaDB node itself if you just have the one. Backup files are saved
to a dedicated Docker volume -
mariadb_backup - and it’s the contents of
this that you should target for transferring backups elsewhere.
Enabling Backup Functionality¶
For backups to work, some reconfiguration of MariaDB is required - this is to enable appropriate permissions for the backup client, and also to create an additional database in order to store backup information.
Firstly, enable backups via
Then, kick off a reconfiguration of MariaDB:
kolla-ansible -i INVENTORY reconfigure -t mariadb
Once that has run successfully, you should then be able to take full and incremental backups as described below.
To perform a full backup, run the following command:
kolla-ansible -i INVENTORY mariadb_backup
Or to perform an incremental backup:
kolla-ansible -i INVENTORY mariadb_backup --incremental
Kolla doesn’t currently manage the scheduling of these backups, so you’ll need to configure an appropriate scheduler (i.e cron) to run these commands on your behalf should you require regular snapshots of your data. A suggested schedule would be:
Daily full, retained for two weeks
Hourly incremental, retained for one day
Backups are performed on your behalf on the designated database node using permissions defined during the configuration step; no password is required to invoke these commands.
Furthermore, backup actions can be triggered from a node with a minimal
installation of Kolla Ansible, specifically one which doesn’t require a copy of
passwords.yml. This is of note if you’re looking to implement automated
backups scheduled via a cron job.
Owing to the way in which Mariabackup performs hot backups, there are some steps that must be performed in order to prepare your data before it can be copied into place for use by MariaDB. This process is currently manual, but the Kolla Mariabackup image includes the tooling necessary to successfully prepare backups. Two examples are given below.
For a full backup, start a new container using the Mariabackup image with the following options on the master database node:
docker run --rm -it --volumes-from mariadb --name dbrestore \ --volume mariadb_backup:/backup \ quay.io/openstack.kolla/centos-source-mariadb-server:master \ /bin/bash (dbrestore) $ cd /backup (dbrestore) $ rm -rf /backup/restore (dbrestore) $ mkdir -p /backup/restore/full (dbrestore) $ gunzip mysqlbackup-04-10-2018.qp.xbc.xbs.gz (dbrestore) $ mbstream -x -C /backup/restore/full/ < mysqlbackup-04-10-2018.qp.xbc.xbs (dbrestore) $ mariabackup --prepare --target-dir /backup/restore/full
Stop the MariaDB instance.
docker stop mariadb
Delete the old data files (or move them elsewhere), and copy the backup into place:
docker run --rm -it --volumes-from mariadb --name dbrestore \ --volume mariadb_backup:/backup \ quay.io/openstack.kolla/centos-source-mariadb-server:master \ /bin/bash (dbrestore) $ rm -rf /var/lib/mysql/* (dbrestore) $ rm -rf /var/lib/mysql/\.[^\.]* (dbrestore) $ mariabackup --copy-back --target-dir /backup/restore/full
Then you can restart MariaDB with the restored data in place:
docker start mariadb docker logs mariadb 81004 15:48:27 mysqld_safe WSREP: Running position recovery with --log_error='/var/lib/mysql//wsrep_recovery.BDTAm8' --pid-file='/var/lib/mysql//scratch-recover.pid' 181004 15:48:30 mysqld_safe WSREP: Recovered position 9388319e-c7bd-11e8-b2ce-6e9ec70d9926:58
This starts off similar to the full backup restore procedure above, but we
must apply the logs from the incremental backups first of all before doing
the final preparation required prior to restore. In the example below, I have
a full backup -
mysqlbackup-06-11-2018-1541505206.qp.xbc.xbs, and an
docker run --rm -it --volumes-from mariadb --name dbrestore \ --volume mariadb_backup:/backup --tmpfs /backup/restore \ quay.io/openstack.kolla/centos-source-mariadb-server:master \ /bin/bash (dbrestore) $ cd /backup (dbrestore) $ rm -rf /backup/restore (dbrestore) $ mkdir -p /backup/restore/full (dbrestore) $ mkdir -p /backup/restore/inc (dbrestore) $ gunzip mysqlbackup-06-11-2018-1541505206.qp.xbc.xbs.gz (dbrestore) $ gunzip incremental-11-mysqlbackup-06-11-2018-1541505223.qp.xbc.xbs.gz (dbrestore) $ mbstream -x -C /backup/restore/full/ < mysqlbackup-06-11-2018-1541505206.qp.xbc.xbs (dbrestore) $ mbstream -x -C /backup/restore/inc < incremental-11-mysqlbackup-06-11-2018-1541505223.qp.xbc.xbs (dbrestore) $ mariabackup --prepare --target-dir /backup/restore/full (dbrestore) $ mariabackup --prepare --incremental-dir=/backup/restore/inc --target-dir /backup/restore/full
At this point the backup is prepared and ready to be copied back into place, as per the previous example.