setup_ansible

##Install ansible on all servers

wget https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
rpm -ivh epel-release-latest-7.noarch.rpm
yum install --enablerepo=epel ansible

##Pick a server for ansible server and allow it access to the remain servers via SSH based authentication

On ansible server
ssh-keygen
Copy the content of /root/.ssh/id_rsa.pub to /root/.ssh/authorized_keys of the remain servers

ssh-copy-id -i root@<IP server>

chmod 600 /root/.ssh/authorized_keys
chmod 700 /root/.ssh
chmod 600 /root/.ssh/id_rsa
chmod 644 /root/.ssh/id_rsa.pub

Disable selinux on other servers

some command for checking:
ansible all -m ping
ansible -m setup <HOST> ### check registered predefined var of ansible host
ansible -m debug -a "var=hostvars[groups['dbservers'][2]]" localhost
ansible -m debug -a "var=hostvars" localhost

Dependencies:
yum install gcc gcc-c++ python-devel MariaDB-devel openssl-devel openssl 
easy_install MySQL-python

Start:
ansible-playbook -s dbservers.yml
ansible-playbook -s dbservers.yml --tags "galera_user"