linux使用yum命令报错Cannot find a valid baseurl for repo: base/7/x86_64

【问题】

在VMware上安装搭建centOS 7虚拟机，配置好网络后，尝试通过yum命令进行安装docker容器。执行命令报错：

已加载插件：fastestmirror, langpacks
Loading mirror speeds from cached hostfile

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 only
safe 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 working
upstream. This is most often useful if you are using a newer
distribution release than is supported by the repository (and the
packages for the previous distribution release still work).

3. Run the command with the repository temporarily disabled
yum --disablerepo=<repoid> ...

4. Disable the repository permanently, so yum won't use it by default. Yum
will then just ignore the repository until you permanently enable it
again or use --enablerepo for temporary usage:

yum-config-manager --disable <repoid>
or
subscription-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 much
slower). If it is a very temporary problem though, this is often a nice
compromise:

yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=true

Cannot find a valid baseurl for repo: base/7/x86_64


【原因】

不知道23年什么时候，国内无法通过docker、yum、npm等命令进行拉取数据源，国外服务器就能正常使用。由于yum源无法找到或无法访问，导致YUM无法正常工作。

【解决】

这个问题可以通过配置使用阿里云或其他国内镜像源进行解决。

编辑CentOS的yum配置：

sudo nano /etc/yum.repos.d/CentOS-Base.repo

直接替换如下配置信息：

[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

按Ctrl+O进行保存，在按Ctrl+X进行退出；
或
按ESC,在输入:wq进行保存退出；

最后清理并重建缓存：

sudo yum clean all
sudo yum makecache
sudo yum update