【Centos】yum 安装软件失败时，切换 Aliyun 镜像源

问题复现

新安装的 Centos 7.9 服务器，在执行 yum 命令来安装工具时，提示异常：

[root@localhost test_build_install_docker]# yum install makeself
已加载插件：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; 未知的错误"One of the configured repositories failed (未知),and yum doesn't have enough cached data to continue. At this point the onlysafe thing yum can do is fail. There are a few ways to work "fix" this:1. Contact the upstream for the repository and get them to fix the problem.2. Reconfigure the baseurl/etc. for the repository, to point to a workingupstream. This is most often useful if you are using a newerdistribution release than is supported by the repository (and thepackages for the previous distribution release still work).3. Run the command with the repository temporarily disabledyum --disablerepo=<repoid> ...4. Disable the repository permanently, so yum won't use it by default. Yumwill then just ignore the repository until you permanently enable itagain or use --enablerepo for temporary usage:yum-config-manager --disable <repoid>orsubscription-manager repos --disable=<repoid>5. Configure the failing repository to be skipped, if it is unavailable.Note that yum will try to contact the repo. when it runs most commands,so will have to try and fail each time (and thus. yum will be be muchslower). If it is a very temporary problem though, this is often a nicecompromise:yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=trueCannot find a valid baseurl for repo: base/7/x86_64
[root@localhost test_build_install_docker]# 

在排除网络问题之后，厂商切换镜像源为Aliyun的。

切换 Aliyun 镜像源

1. 备份原始镜像源

cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

2. 配置新的镜像源

sudo tee /etc/yum.repos.d/CentOS-Base.repo <<-'EOF'
[base]
name=CentOS-$releasever - Base
baseurl=http://mirrors.aliyun.com/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7[updates]
name=CentOS-$releasever - Updates
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-$releasever - Extras
baseurl=http://mirrors.aliyun.com/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7EOF

3. 清理缓存并更新

yum clean all
yum makecache
yum update

切记更新后内核版本可能不同于之前同一个镜像安装的服务器了。介意新环境与其他环境有差异的，就别使用更新镜像源的方式安装工具了，看下有没有不用 yum 安装，手动安装的方式。