To install GitLab using the omnibus package on a CentOS, Red Hat Enterprise Linux (RHEL), Scientific Linux, or Oracle Linux system, make sure that you have a server with a base that's compatible with CentOS 7.

First, you'll need to connect to a Terminal session and make sure that a few key packages are installed by running the following commands:

sudo yum install -y curl policycoreutils-python openssh-server

Now, you'll need to allow HTTP and SSH traffic through the local device firewall. This can be done by running the following code lines:

sudo systemctl enable sshd
sudo systemctl start sshd
sudo firewall-cmd --permanent --add-service=http
sudo systemctl reload firewalld

Next, you'll need to decide on whether you want to use Postfix to send notification emails or external SMTP provider. While the latter is...