In order to use the extra packages provided by EPEL, the repository needs to be added to your system.

Enable the EPEL repository

$ sudo yum-config-manager --add-repo=https://dl.fedoraproject.org/pub/epel/7/x86_64/

Download the EPEL GPG key

$ sudo wget -O /etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7 https://dl.fedoraproject.org/pub/epel/RPM-GPG-KEY-EPEL-7

Install the GPG key

$ sudo rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7

Clean the local yum repository data

$ sudo yum clean all

And we are good to go!