1. Install and configure the necessary dependencies

sudo yum install curl policycoreutils openssh-server openssh-clients
sudo systemctl enable sshd
sudo systemctl start sshd
sudo yum install postfix
sudo systemctl enable postfix
sudo systemctl start postfix
sudo firewall-cmd --permanent --add-service=http
sudo systemctl reload firewalld

2. Add the GitLab package server and install the package

通过下面链接下载『gitlab-ce-8.5.1-ce.0.el7.x86_64.rpm』：
http://pan.baidu.com/s/1qXeuiNq

有想法的同学可以下载『https://packages.gitlab.com/gitlab/gitlab-ce/』自己想要的版本

下载完成之后当然是安装了：sudo rpm -i gitlab-ce-8.5.1-ce.0.el7.x86_64.rpm

3. Configure and start GitLab

sudo gitlab-ctl reconfigure

4. Browse to the hostname and login

Username: root 
Password: 5iveL!fe
通过浏览器访问：http://localhost   或者  http://ip

登录成功，首次登录需修改密码

配置：
sudo mkdir -p /etc/gitlab
sudo touch /etc/gitlab/gitlab.rb
sudo chmod 600 /etc/gitlab/gitlab.rb

Configuring the external URL for GitLab：

向：/etc/gitlab/gitlab.rb 文件中添加：
external_url "http://gitlab.example.com"

更改配置后，执行如下命令（加载配置生效）：
sudo gitlab-ctl reconfigure

服务打开、关闭、重启：
# Start all GitLab components
sudo gitlab-ctl start

# Stop all GitLab components
sudo gitlab-ctl stop

# Restart all GitLab components
sudo gitlab-ctl restart