*`replication.yml`: install and configure prerequisites for mysql replication, do not forget to set `mysql_bind_address`, `mysql_server_id` and `mysql_log_bin`
*`mysql_bind_address` : (default: `Null`, default evolinux config is then used) ;
*`mysql_max_connections`: maximum number of simultaneous connections (default: `Null`, default evolinux config is then used) ;
*`mysql_max_connect_errors`: number of permitted successive interrupted connection requests before a host gets blocked (default: `Null`, default evolinux config is then used) ;
*`mysql_table_cache`: (default: `Null`, default evolinux config is then used) ;
*`mysql_tmp_table_size`: (default: `Null`, default evolinux config is then used) ;
*`mysql_max_heap_table_size`: (default: `Null`, default evolinux config is then used) ;
*`mysql_query_cache_limit`: (default: `Null`, default evolinux config is then used) ;
*`mysql_log_bin`: (default: `Null`, activates binlogs if used with `mysql_replication`) ;
*`mysql_repl_password`: Password hash for replication user, only creates a user if set.
## Notes
Changing the _datadir_ location can be done multiple times, as long as it is not restored to the default initial location, (because a symlink is created and can't be switched back, yet).
When using replication, note that the connections from the client server on the haproxy 8306 and mysql 3306 ports need to be open and the sql servers need to communicate on port 3306.