Make charset and collation configurables

MariaDB 11.5 has introduced changes to default collation, switching
to uca1400_ai_ci from general_ci [1]
With that they've also introduced changes to default value of
character-set-collations value, which now has precedence over
collation-server/collation-connection if CHARSET is supplied in request
leading to potential conflicts [3] when performing migrations.

We introduce set of new variables to be able to control and potentially
switch to new collation/charsets by default in the future, while
enabling us to keep current behavior.

[1] https://mariadb.com/docs/release-notes/community-server/old-releases/release-notes-mariadb-11-5-rolling-releases/what-is-mariadb-115#other
[2] https://mariadb.com/docs/server/server-management/variables-and-modes/server-system-variables#character_set_collations
[3] https://jira.mariadb.org/browse/MDEV-37544

Related-Bug: #2121797
Change-Id: I5adcd1f2d5160410fb9ded8e7f967e9773434e35
Signed-off-by: Dmitriy Rabotyagov <dmitriy.rabotyagov@cleura.com>

defaults/main.yml

@@ -127,6 +127,17 @@ galera_wait_timeout: "{{ openstack_db_connection_recycle_time | default('600') }
 # to timeout
 galera_startup_timeout: 1800
 
+## charset options
+galera_default_charset: utf8mb3
+galera_default_collation: general_ci
+# NOTE: Default collation set will be updated with defined above defaults
+galera_default_collation_set:
+  utf8mb3: utf8mb3_uca1400_ai_ci
+  utf8mb4: utf8mb4_uca1400_ai_ci
+  ucs2: ucs2_uca1400_ai_ci
+  utf16: utf16_uca1400_ai_ci
+  utf32: utf32_uca1400_ai_ci
+
 ## innodb options
 galera_innodb_buffer_pool_size: 4096M
 galera_innodb_log_file_size: 1024M

releasenotes/notes/galera_charset_collation-00cd59785a60a832.yaml

@@ -0,0 +1,11 @@
+---
+features:
+  - |
+    Added new variables to control MariaDB default charset and collation:
+
+    * galera_default_charset
+    * galera_default_collation
+    * galera_default_collation_set
+
+    Variable ``galera_default_collation_set`` is defined in my.cnf only for
+    MariaDB versions >= 11.5.

templates/my.cnf.j2

@@ -17,16 +17,17 @@ socket = "{{ galera_var_run_socket }}"
 socket = "{{ galera_var_run_socket }}"
 nice = 0
 
-
 [mysql]
-default-character-set = utf8
-
+default-character-set = {{ galera_default_charset }}
 
 [mysqld]
 user = mysql
-collation-server = utf8_general_ci
-init-connect = 'SET NAMES utf8'
-character-set-server = utf8
+collation-server = {{ _galera_collation }}
+init-connect = 'SET NAMES {{ galera_default_charset }} COLLATE {{ _galera_collation }}'
+character-set-server = {{ galera_default_charset }}
+{% if galera_major_version is version('11.5', '>=') and galera_install_method == 'external_repo' %}
+character-set-collations = {{ _galera_collation_set.items() | map('join', '=') | join(',') }}
+{% endif %}
 datadir = {{ galera_data_dir }}
 tmpdir = {{ galera_tmp_dir }}
 {% for ignored_db in galera_ignore_db_dirs %}

vars/main.yml

@@ -12,6 +12,10 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+
+_galera_collation: "{{ [galera_default_charset, galera_default_collation] | join('_') }}"
+_galera_collation_set: "{{ galera_default_collation_set | combine({galera_default_charset: _galera_collation}) }}"
+
 galera_init_defaults:
   Service:
     LimitNOFILE: "{{ galera_file_limits }}"