see also: https://about.gitlab.com/downloads/
sudo yum install curl openssh-server postfix cronie -y
sudo service postfix start
sudo chkconfig postfix on
sudo lokkit -s http -s ssh
curl https://packages.gitlab.com/install/repositories/gitlab/gitlab-ce/script.rpm.sh | sudo bash
sudo yum install gitlab-ce -y
sudo gitlab-ctl reconfigure
If following error is occurred, see blogs bellow.(but unresolved yet)
Failed dependencies: rpmlib(TildeInVersions) <= 4.10.0-1 is needed by gitlab-ce-xxxxx
Did you find a resolution for that?