解决近期CentOS YUM更新出错问题

由于centos7停止更新，近期CentOS在进行yum操作时，会出现Mirrorlist镜像源报错的问题。

Loaded plugins: fastestmirror
Determining fastest mirrors
Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=stock error was
14: curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error"

官方已将原本的镜像列表（Mirrorlist）下架并归档，导致原始链接无法再访问原来的镜像源。

以下为最简单的解决方式

1. 直接执行以下两行命令：

sudo sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*
sudo sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-*

2. 清理YUM缓存并生成新缓存:

sudo yum clean all
sudo yum makecache

3. 更新系统：

sudo yum update

国内节点：

https://mirrors.tuna.tsinghua.edu.cn/centos-vault/

vi /etc/yum.repos.d/CentOS-Base.repo

# CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client.  You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the 
# remarked out baseurl= line instead.
#
#
 
[base]
name=CentOS-$releasever - Base - mirrors.aliyun.com
failovermethod=priority
baseurl=http://mirrors.aliyun.com/centos/$releasever/os/$basearch/
        http://mirrors.cqu.edu.cn/centos/$releasever/os/$basearch/
        http://mirrors.cloud.tencent.com/centos/$releasever/os/$basearch/
        http://mirrors.cqupt.edu.cn/centos/$releasever/os/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
 
#released updates 
[updates]
name=CentOS-$releasever - Updates - mirrors.aliyun.com
failovermethod=priority
baseurl=http://mirrors.aliyun.com/centos/$releasever/updates/$basearch/
        http://mirrors.cqu.edu.cn/centos/$releasever/updates/$basearch/
        http://mirrors.cloud.tencent.com/centos/$releasever/updates/$basearch/
        http://mirrors.cqupt.edu.cn/centos/$releasever/updates/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
 
#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras - mirrors.aliyun.com
failovermethod=priority
baseurl=http://mirrors.aliyun.com/centos/$releasever/extras/$basearch/
        http://mirrors.cqu.edu.cn/centos/$releasever/extras/$basearch/
        http://mirrors.cloud.tencent.com/centos/$releasever/extras/$basearch/
        http://mirrors.cqupt.edu.cn/centos/$releasever/extras/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
 
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus - mirrors.aliyun.com
failovermethod=priority
baseurl=http://mirrors.aliyun.com/centos/$releasever/centosplus/$basearch/
        http://mirrors.cqu.edu.cn/centos/$releasever/centosplus/$basearch/
        http://mirrors.cloud.tencent.com/centos/$releasever/centosplus/$basearch/
        http://mirrors.cqupt.edu.cn/centos/$releasever/centosplus/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
gpgcheck=1
enabled=0
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
 
#contrib - packages by Centos Users
[contrib]
name=CentOS-$releasever - Contrib - mirrors.aliyun.com
failovermethod=priority
baseurl=http://mirrors.aliyun.com/centos/$releasever/contrib/$basearch/
        http://mirrors.cqu.edu.cn/centos/$releasever/contrib/$basearch/
        http://mirrors.cloud.tencent.com/centos/$releasever/contrib/$basearch/
        http://mirrors.cqupt.edu.cn/centos/$releasever/contrib/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib
gpgcheck=1
enabled=0
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

华为云节点
CentOS-Vault的镜像地址为：

https://mirrors.huaweicloud.com/centos-vault/

1、备份配置文件：

cp -a /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak

2、配置下列方案。
执行如下命令：

wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.huaweicloud.com/artifactory/os-conf/centos/centos-7.repo

3、执行

yum clean all

清除原有 yum 缓存

4、执行

yum makecache

（刷新缓存）或者

yum repolist all

（查看所有配置可以使用的文件，会自动刷新缓存）。