Added my.cnf with openstack recommended settings.

roles/mariadb/files/my.cnf

@@ -0,0 +1,68 @@
+[client]
+port            = 3306
+socket          = /var/run/mysqld/mysqld.sock
+
+
+[mysqld_safe]
+socket          = /var/run/mysqld/mysqld.sock
+nice            = 0
+
+[mysqld]
+skip-host-cache
+skip-name-resolve
+pid-file        = /var/run/mysqld/mysqld.pid
+socket          = /var/run/mysqld/mysqld.sock
+port            = 3306
+basedir         = /usr
+datadir         = /var/lib/mysql
+tmpdir          = /tmp
+lc_messages_dir = /usr/share/mysql
+lc_messages     = en_US
+skip-external-locking
+connect_timeout         = 5
+wait_timeout            = 600
+max_allowed_packet      = 16M
+thread_cache_size       = 128
+sort_buffer_size        = 4M
+bulk_insert_buffer_size = 16M
+tmp_table_size          = 32M
+max_heap_table_size     = 32M
+myisam_recover_options = BACKUP
+key_buffer_size         = 128M
+table_open_cache        = 400
+myisam_sort_buffer_size = 512M
+concurrent_insert       = 2
+read_buffer_size        = 2M
+read_rnd_buffer_size    = 1M
+query_cache_limit               = 128K
+query_cache_size                = 64M
+slow_query_log_file     = /var/log/mysql/mariadb-slow.log
+long_query_time = 10
+
+expire_logs_days        = 10
+max_binlog_size         = 100M
+default_storage_engine  = InnoDB
+innodb_buffer_pool_size = <t_CO>M
+innodb_log_buffer_size  = 8M
+innodb_file_per_table   = 1
+innodb_open_files       = 400
+innodb_io_capacity      = 400
+innodb_flush_method     = O_DIRECT
+
+default-storage-engine = innodb
+max_connections = 4096
+collation-server = utf8_general_ci
+character-set-server = utf8
+
+[galera]
+
+[mysqldump]
+quick
+quote-names
+max_allowed_packet      = 16M
+
+[mysql]
+
+[isamchk]
+key_buffer              = 16M
+

roles/mariadb/files/mysql.service

@@ -2,15 +2,17 @@
 Description=Mariadb Container
 After=docker.service
 Requires=docker.service
- 
+
 [Service]
 TimeoutStartSec=0
 Restart=always
 ExecStartPre=-/usr/bin/docker stop %n
 ExecStartPre=-/usr/bin/docker rm %n
 ExecStartPre=/usr/bin/docker pull mariadb:10.2
-ExecStart=/usr/bin/docker run  -p 3306:3306 --name %n -v /srv/lib/mysql:/var/lib/mysql \
+ExecStart=/usr/bin/docker run  -p 3306:3306 --name %n \
+ -v /srv/mariadb/lib/mysql:/var/lib/mysql \
+ -v /srv/mariadb/etc/mysql:/etc/mysql \
  -e MYSQL_ROOT_PASSWORD=geheim mariadb:10.2
- 
+
 [Install]
 WantedBy=multi-user.target

roles/mariadb/tasks/main.yml

@@ -8,8 +8,21 @@
     mode: 644
     owner: root
     group: root
-- name: install service file
-  command: systemctl daemon-reload
+
+- name: make mariadb settings volume
+  file:
+    path: /srv/mariadb/etc/mysql
+    state: directory
+    mode: 0777
+
+- name: place settings file
+  copy:
+    src: files/my.cnf
+    dest: /srv/mariadb/etc/mysql
+    mode: 660
+
+- command: systemctl daemon-reload
+
 - name: make sure service is started
   systemd:
     name: mysql.service