進入對應目錄
# cd  /etc/yum.repos.d
備份原來yum源
# mkdir bak && mv Ce* bak/
復制yum源文件
# cp -r  bak/CentOS-Base.repo  ./
編輯yum源文件
# vim CentOS-Base.repo
刪除原有內容，替換配置內容如下：

[base]
name=CentOS-$releasever - Base - mirrors.aliyun.com
baseurl=http://mirrors.aliyun.com/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
 
[updates]
name=CentOS-$releasever - Updates - mirrors.aliyun.com
baseurl=http://mirrors.aliyun.com/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
 
[extras]
name=CentOS-$releasever - Extras - mirrors.aliyun.com
baseurl=http://mirrors.aliyun.com/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
 
[centosplus]
name=CentOS-$releasever - Plus - mirrors.aliyun.com
baseurl=http://mirrors.aliyun.com/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

保存配置
修改yum 源：
安裝 wget：yum install wget -y
安裝阿里 yum源 和 epel源

# wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo
 
# wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo

驗證
# yum update