Step-by-Step Guide to Installing and Configuring GitLab on CentOS 6

Prepare a virtual machine running CentOS 6 and download the appropriate GitLab dependency package from the official website.

Install the required system packages:

sudo yum install openssh-server

sudo yum install postfix

sudo yum install cronie

Start and enable the services:

sudo service postfix start

sudo chkconfig postfix on

sudo lokkit -s http -s ssh

Download the GitLab omnibus RPM (or copy it to the server if the network blocks the download) and install it:

curl -O https://downloads-packages.s3.amazonaws.com/centos-6.6/gitlab-7.9.0_omnibus.2-1.el6.x86_64.rpm

sudo rpm -i gitlab-7.9.0_omnibus.2-1.el6.x86_64.rpm

If the RPM fails due to size mismatch, transfer the file via scp from another host and reinstall.

Configure GitLab by editing /etc/gitlab/gitlab.rb . Set the external URL and add LDAP configuration, for example:

external_url = 'http://gitlab.test.com'

gitlab_rails['ldap_enabled'] = true

gitlab_rails['ldap_servers'] = YAML.load <<-EOS

main:

label: 'LDAP'

host: 'xxx.xxx.xxx.xxx'

port: 389

uid: 'sAMAccountName'

bind_dn: '[email protected]'

password: '******'

base: 'DC=xxxxxx,DC=com'

EOS

Usually no changes are needed in /var/opt/gitlab/gitlab-rails/etc/gitlab.yml unless specific customizations are required.

Apply the configuration and start GitLab:

sudo gitlab-ctl reconfigure

Check the status of all components:

sudo gitlab-ctl status

Restart GitLab if necessary:

sudo gitlab-ctl restart

Access the web UI (e.g., http://localhost or the configured hostname), log in with the default administrator account (username: root , password: 5iveL!fe ), and change the password on first login.

Configure SSH keys for password‑less Git operations: generate a key with ssh-keygen -t rsa -C "[email protected]" , copy the public key ( ~/.ssh/id_rsa.pub ) into GitLab’s SSH key field, and verify that pushes and clones work without prompting for credentials.

Common troubleshooting steps include re‑running sudo gitlab-ctl reconfigure when encountering "retry later" or 422 errors, checking for port conflicts with Apache/httpd (kill or remove httpd if it blocks GitLab), and ensuring the correct hostname/IP is set in external_url and the local /etc/hosts file.

When migrating to a new GitLab server, update DNS or host entries to point to the new IP, delete the old ~/.ssh/known_hosts entry, and re‑add the SSH key to avoid clone failures.