1. Import Key, see here
sudo apt-get install software-properties-common
sudo apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0xcbcb082a1bb943db
sudo add-apt-repository 'deb [arch=amd64,i386] http://mariadb.biz.net.id/repo/10.1/ubuntu trusty main'