Use separate tmp directory

During upgrades or cluster repairments, temporary directories are created
inside /var/lib/mysql and treated as databases. This results in errors
during mysqlcheck like:

`Got error: 1102: Incorrect database name '#mysql50#tmp.stLr46FBlt'`

Path outside of datadir is not choosen since it could be separate mount
point and it's important for replication
to survive reboots.

Change-Id: Ia110dd9ed09b04f6bb7a0a3adf5a808966558507

defaults/main.yml

@@ -99,6 +99,9 @@ galera_gcache_size: 1024M
 
 galera_max_heap_table_size: 32M
 galera_tmp_table_size: 32M
+galera_tmp_dir: /var/lib/mysql/#tmp
+galera_ignore_db_dirs:
+  - "'#tmp'"
 
 galera_file_limits: 65535
 galera_wait_timeout: "{{ openstack_db_connection_recycle_time | default('600') }}"

releasenotes/notes/galera_tmpdir-3271e0bc8e353930.yaml

@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    New variables ``galera_tmp_dir`` and ``galera_ignore_db_dirs`` were
+    implemented to control path to tmp dir and what directories should be
+    ignored when listing databases.
+upgrade:
+  - |
+    If you have database named as ``#tmp`` you should change ``galera_tmp_dir``
+    path and adjust ``galera_ignore_db_dirs`` or rename database.

tasks/galera_server_post_install.yml

@@ -111,6 +111,7 @@
     recurse: "{{ item.recurse|default('false') }}"
   with_items:
     - { path: "/var/lib/mysql", owner: "mysql", mode: "02755" }
+    - { path: "{{ galera_tmp_dir }}", owner: "mysql", mode: "02755" }
     - { path: "/etc/mysql/conf.d" }
 
 - name: Create and install SSL certificates

templates/my.cnf.j2

@@ -28,7 +28,9 @@ collation-server = utf8_general_ci
 init-connect = 'SET NAMES utf8'
 character-set-server = utf8
 datadir = /var/lib/mysql
-tmpdir = /var/lib/mysql
+tmpdir = {{ galera_tmp_dir }}
+ignore_db_dirs = {{ galera_ignore_db_dirs | join(',') }}
+
 bind-address = {{ galera_server_bind_address }}
 {% if galera_server_id is defined %}
 server-id = {{ galera_server_id }}