remove the fail logic and add the informational message

playbooks/roles/mysql/defaults/main.yml

 ---
+remove_experimental_mysql: false
+
 mysql_debian_pkgs:
-  - software-properties-common
+  - "mysql-server-5.6"
   - python-mysqldb
-  - "mysql-server=5.6.*"
+  

playbooks/roles/mysql/tasks/main.yml

 ---
-- name: Add MySQL experimental apt key
-  apt_key:
-    id: 4F4EA0AAE5267A6C
-    keyserver: "{{ COMMON_EDX_PPA_KEY_SERVER }}"
-    state: present
-    
-- name: Install apt repository
-  apt_repository:
-    repo: 'deb http://ppa.launchpad.net/ondrej/mysql-experimental/ubuntu precise main'
-    update_cache: yes
+- name: Look for mysql 5.6
+  shell: "dpkg -s mysql-server"
+  ignore_errors: yes
+  register: mysql_56_installed
+  changed_when: no
 
-- name: install mysql 56 and dependencies
-  apt: 
-    name: "{{ item }}" 
-    install_recommends: yes 
-    force: yes 
-    state: present
-  with_items: mysql_debian_pkgs
+- name: Important message
+  debug:
+    msg: |
+      "MySQL experimental is already installed, make 'remove_experimental_mysql: true' in defaults/main.yml, 
+      if you want to remove it and install the stable version of MySQL"
+  when: "'5.6.14' in  mysql_56_installed.stdout and not remove_experimental_mysql"
 
-- name: start mysql
-  service: 
-    name: mysql 
-    state: started
+- pause:
+    seconds: 10
+  when: "'5.6.14' in  mysql_56_installed.stdout and not remove_experimental_mysql"
 
-- name: Ensure Anonymous user(s) does not exist
-  mysql_user: 
-    name: '' 
-    host: "{{ item }}" 
-    state: absent
-  with_items:
-    - localhost
-    - "{{ ansible_hostname }}"
+# remove this, once the new devstack is out
+- include: remove_mysql_experimental.yml
+  when: remove_experimental_mysql
+
+- include: mysql.yml
+  when: (mysql_56_installed.rc == 1) or (remove_experimental_mysql)
\ No newline at end of file

playbooks/roles/mysql/tasks/mysql.yml

+---
+# Here are the few steps that I have performed to get the `debconf` setting information:
+#
+# - downloaded the mysql-apt-repo from the mysql official site(named: mysql-apt-config_0.6.0-1_all.deb)
+# - Find the `debconf` setting information after installing this `deb` package
+# 
+# # debconf-show mysql-apt-config
+# * mysql-apt-config/select-server: mysql-5.6
+#   mysql-apt-config/unsupported-platform: abort
+#   mysql-apt-config/repo-codename: precise
+# * mysql-apt-config/select-product: Apply
+#   mysql-apt-config/select-tools:
+#   mysql-apt-config/repo-distro: ubuntu
+# 
+# - Even to get more information about the `debconf` options of the package:
+# 
+# # debconf-get-selections|grep mysql-apt-config
+# mysql-apt-config  mysql-apt-config/select-server  select  mysql-5.6
+# mysql-apt-config  mysql-apt-config/unsupported-platform select  abort
+# mysql-apt-config  mysql-apt-config/repo-codename  select  precise
+# mysql-apt-config  mysql-apt-config/select-product select  Apply
+# mysql-apt-config  mysql-apt-config/select-tools select
+# mysql-apt-config  mysql-apt-config/repo-distro  select  ubuntu
+# 
+# - After the installation, I have checked the `/etc/apt/sources.list.d` directory and found one file `mysql.list` 
+# with following contents:
+# 
+# deb http://repo.mysql.com/apt/ubuntu/ precise mysql-apt-config
+# deb http://repo.mysql.com/apt/ubuntu/ precise mysql-5.6
+# deb-src http://repo.mysql.com/apt/ubuntu/ precise mysql-5.6
+# 
+#
+# Thought that instead of performing all those steps and get the repo, why not directly use this repo 
+# `deb http://repo.mysql.com/apt/ubuntu/ precise mysql-5.6`, I just picked this line and directly used it and it worked for us. 
+
+- name: Add MySQL community apt key
+  apt_key:
+    id: 8C718D3B5072E1F5
+    keyserver: "{{ COMMON_EDX_PPA_KEY_SERVER }}"
+    state: present
+
+- name: Install MySQL community apt repositories
+  apt_repository:
+    repo: "deb http://repo.mysql.com/apt/ubuntu/ precise mysql-5.6"
+    update_cache: yes
+
+- name: Install mysql-5.6 and dependencies
+  apt: 
+    name: "{{ item }}" 
+    install_recommends: yes
+    state: present
+  with_items: mysql_debian_pkgs
+
+- name: Start mysql
+  service: 
+    name: mysql 
+    state: started
+
+- name: Ensure Anonymous user(s) does not exist
+  mysql_user: 
+    name: '' 
+    host: "{{ item }}" 
+    state: absent
+  with_items:
+    - localhost
+    - "{{ ansible_hostname }}"

playbooks/roles/mysql/tasks/remove_mysql_experimental.yml

+---
+- name: Stop mysql service
+  service: 
+    name: mysql 
+    state: stopped
+
+- name: Remove experimental apt repository
+  apt_repository:
+    repo: 'deb http://ppa.launchpad.net/ondrej/mysql-experimental/ubuntu precise main'
+    state: absent
+
+- name: Remove experimental version of mysql
+  apt: 
+    name: "{{ item }}" 
+    state: absent 
+    purge: yes
+  with_items:
+    - mysql-server-5.6
+    - mysql-server
\ No newline at end of file