解决docker构建centos7时yum命令报错、镜像源失效问题

使用dockerfile构建centos7镜像遇到

1.185 Determining fastest mirrors
21.73 Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infr  a=container error was
21.73 14: curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error"

解决方法：在dockerfile中的RUN yum命令之前添加以下内容

RUN rm -f /etc/yum.repos.d/*.repo && \echo -e '[base]\n\
name=CentOS-7 - Base\n\
baseurl=https://mirrors.aliyun.com/centos-vault/7.9.2009/os/$basearch/\n\
gpgcheck=0\n\
\n\
[updates]\n\
name=CentOS-7 - Updates\n\
baseurl=https://mirrors.aliyun.com/centos-vault/7.9.2009/updates/$basearch/\n\
gpgcheck=0\n\
\n\
[extras]\n\
name=CentOS-7 - Extras\n\
baseurl=https://mirrors.aliyun.com/centos-vault/7.9.2009/extras/$basearch/\n\
gpgcheck=0' > /etc/yum.repos.d/CentOS-Base.repo && \yum clean all && \yum makecache