How can Docker help a MariaDB cluster for Disaster/Recovery

https://blog.dbi-services.com/how-can-docker-help-a-mariadb-cluster-for-disaster-recovery/

This post is a work in progress ; On the above link is the original ideea ;

Mistakes or accidental data deletions can sometimes happen on a productive MariaDB Galera Cluster and this can be disastrous.
There are so many cases I have heard by customers and hereafter are some of the most common:
– dropping one column of a table
– dropping one table
– updating a big table without a where clause
What if it was possible to restore online a subset of data without downtime?

MariaDB preparation

We need some help from Docker ; 
Using a delayed node (the helper), we can deploy a container with a delayed replication of 15minutes,  but of course you can choose your own lags.

MariaDB > create user rpl_user@’192.168.56.%' IDENTIFIED BY 'manager';

MariaDB > GRANT REPLICATION SLAVE ON *.* TO rpl_user@'%’;

MariaDB > show grants for 'rpl_user'@'’192.168.56.%';

+-------------------------------------------------------------------------------------+

| Grants for rpl_user@%                                                               |

+-------------------------------------------------------------------------------------+

| GRANT REPLICATION SLAVE ON *.* TO 'rpl_user'@'’192.168.56.%'             |

+-------------------------------------------------------------------------------------+




$ vi /storage/mariadb-slave-15m/mariadb.conf.d/my.cnf

[mysqld]

server_id=10015

binlog_format=ROW

log_bin=binlog

log_slave_updates=1

relay_log=relay-bin

expire_logs_days=7

read_only=ON




The most important parameter is “MASTER_DELAY” as it determines the amount of time in seconds the slave should lag behind the master.
CHANGE MASTER TO MASTER_HOST = '192.168.56.203’, \ MASTER_USER = 'rpl_user', MASTER_PASSWORD = 'manager’, \ MASTER_DELAY=900; START SLAVE