mysql: better support for check mode

mysql/tasks/users_jessie.yml

@@ -13,6 +13,7 @@
   command: "apg -n 1 -m 16 -M lcN"
   register: mysql_admin_password
   changed_when: False
+  check_mode: no
   tags:
   - mysql
 

mysql/tasks/utils.yml

@@ -30,9 +30,10 @@
   when: ansible_distribution_major_version | version_compare('9', '>=')
 
 - name: Read debian-sys-maint password
-  shell: cat /etc/mysql/debian.cnf | grep -m1 "password = .*" | cut -d" " -f3
+  shell: 'cat /etc/mysql/debian.cnf | grep -m1 "password = .*" | cut -d" " -f3'
   register: mysql_debian_password
   changed_when: False
+  check_mode: no
   tags:
     - mysql
 

redis/tasks/munin.yml

@@ -53,6 +53,7 @@
   register: munin_redis_blocs_in_config
   failed_when: False
   changed_when: False
+  check_mode: no
 
 - name: Add redis password for munin (if no more than 1 config block)
   ini_file: