Only setup backup when rsnapshot is configured, don't use password for root auth

Mysql doesn't need a root password to authenticate root locally. And without rsnapshot installed, configuring rsnapshot config doesn't work.

mysql/tasks/main.yml

@@ -24,56 +24,41 @@
     state: started
     enabled: true
 
-- name: ensure the mysql root user exists and has the correct password
-  mysql_user:
-    name: root
-    password: "{{ mysql_root_password }}"
-    login_user: root
-    login_password: "{{ mysql_root_password }}"
-  register: mysql_root_creation_result
-  no_log: true
-  ignore_errors: true
+- name: setup mysql backups with rsnapshot
+  when: '"servers_rsnapshot" in group_names'
+  block:
+    - name: ensure a read-only mysql user for backups exists
+      mysql_user:
+        name: "{{ mysql_backup_user }}"
+        password: "{{ mysql_backup_password }}"
+        priv: "*.*:SELECT,LOCK TABLES"
+      no_log: true
 
-- name: initialize the mysql root user
-  mysql_user:
-    name: root
-    password: "{{ mysql_root_password }}"
-  no_log: true
-  when: mysql_root_creation_result is failed
+    - name: ensure the backup procedure can access the backup password
+      template:
+        src: my.cnf
+        dest: "/root/.mysql-{{ mysql_backup_user }}.cnf"
+        owner: root
+        group: root
+        mode: '0600'
 
-- name: ensure a read-only mysql user for backups exists
-  mysql_user:
-    name: "{{ mysql_backup_user }}"
-    password: "{{ mysql_backup_password }}"
-    login_user: root
-    login_password: "{{ mysql_root_password }}"
-    priv: "*.*:SELECT,LOCK TABLES"
+    - name: deploy the mysql backup script
+      template:
+        src: mysqlbackup.sh
+        dest: /usr/local/bin/
+        owner: root
+        group: root
+        mode: '0755'
 
-- name: ensure the backup procedure can access the backup password
-  template:
-    src: my.cnf
-    dest: "/root/.mysql-{{ mysql_backup_user }}.cnf"
-    owner: root
-    group: root
-    mode: '0600'
+    - name: ensure we backup all the mysql databases with rsnapshot
+      copy:
+        src: rsnapshot.conf
+        dest: /etc/rsnapshot.d/mysql.conf
+        owner: root
+        group: root
+        mode: '0644'
 
-- name: deploy the mysql backup script
-  template:
-    src: mysqlbackup.sh
-    dest: /usr/local/bin/
-    owner: root
-    group: root
-    mode: '0755'
-
-- name: ensure we backup all the mysql databases with rsnapshot
-  copy:
-    src: rsnapshot.conf
-    dest: /etc/rsnapshot.d/mysql.conf
-    owner: root
-    group: root
-    mode: '0644'
-
-- name: remove obsolete crontab
-  file:
-    path: /etc/cron.d/mysql-snapshot
-    state: absent
+    - name: remove obsolete crontab
+      file:
+        path: /etc/cron.d/mysql-snapshot
+        state: absent