INSTALL SYSTEM DEPENDENCIES

This is the short list of dependencies you will need to start your server up from a base EL7 install:

    sudo yum install curl policycoreutils openssh-server openssh-clients postfix

ENABLE SERVICES

The server will need postfix for messaging and ssh for git and management. Here is how to configure this:

    sudo systemctl enable sshd
    sudo systemctl start sshd
    sudo systemctl enable postfix
    sudo systemctl start postfix

SETUP FIREWALL

Add HTTP, HTTPS, and ensure that SSH is correctly setup.

    sudo firewall-cmd --permanent --add-service=ssh
    sudo firewall-cmd --permanent --add-service=http
    sudo firewall-cmd --permanent --add-service=https
    sudo systemctl reload firewalld

INSTALL GITLAB-CE

Download, install, and configure gitlab-ce:

    curl -sS https://packages.gitlab.com/install/repositories/gitlab/gitlab-ce/script.rpm.sh | sudo bash
    sudo yum install gitlab-ce
    sudo gitlab-ctl reconfigure

FINAL STEPS

This should yield a functional server, last thing is to visit the site and create your 'root' password, which will grant you a Administrator level account that can be used to configure the server further.