Here is your custom MariaDB YUM repository entry for CentOS. Copy and paste it into a file under /etc/yum.repos.d/ (we suggest naming the file MariaDB.repo or something similar).
#MariaDB 5.5 CentOS repository list - created 2015-10-14 17:48 UTC
#http://mariadb.org/mariadb/repositories/ [mariadb] name = MariaDB baseurl = http://yum.mariadb.org/5.5/centos7-amd64 gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDB gpgcheck=1
After the file is in place, install MariaDB with:
sudo yum install MariaDB-server MariaDB-client
If you haven't already accepted the MariaDB GPG key, you will be prompted to do so. See "Installing MariaDB with yum" for detailed information.