Centos7 使用yum命令安裝軟件失敗，報錯"Couldn't open file /media/cdrom/repodata/repomd.xml"

今天使用CentOS7安裝docker的時候，安裝失敗，報錯

# yum install docker
已加載插件：fastestmirror, langpacks
file:///media/cdrom/repodata/repomd.xml: [Errno 14] curl#37 - "Couldn't open file /media/cdrom/repodata/repomd.xml"
正在嘗試其它鏡像。
Loading mirror speeds from cached hostfile
沒有可用軟件包 docker。
錯誤：無須任何處理

解決：

1. 進入“/etc/yum.repos.d”，刪除“CentOS-Media.repo”
2. 此時直接安裝會報錯，即沒有“CentOS-Media.repo”時，使用yum出錯

   # yum install docker
   已加載插件：fastestmirror, langpacks
   Loading mirror speeds from cached hostfile
   There are no enabled repos.
    Run "yum repolist all" to see the repos you have.
    To enable Red Hat Subscription Management repositories:
        subscription-manager repos --enable <repo>
    To enable custom repositories:
        yum-config-manager --enable <repo>

    

3. 重新導入”CentOS-Media.repo“

4. 安裝成功。（文末附CentOS-Media.repo內容）

   # cd /etc/yum.repos.d
   # rm -rf CentOS-Media.repo 
   # mv CentOS7-Base-163.repo CentOS-Base.repo
   # yum install docker

    CentOS-Base.repo正確內容，只要是repo後綴就可以了。

   []# vim 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-$releasever - Base - 163.com
   #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
   baseurl=http://mirrors.163.com/centos/$releasever/os/$basearch/
   gpgcheck=1
   gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
   
   #released updates
   [updates]
   name=CentOS-$releasever - Updates - 163.com
   #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
   baseurl=http://mirrors.163.com/centos/$releasever/updates/$basearch/
   gpgcheck=1
   gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
   
   #additional packages that may be useful
   [extras]
   name=CentOS-$releasever - Extras - 163.com
   #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
   baseurl=http://mirrors.163.com/centos/$releasever/extras/$basearch/
   gpgcheck=1
   gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7
   
   #additional packages that extend functionality of existing packages
   [centosplus]
   name=CentOS-$releasever - Plus - 163.com
   baseurl=http://mirrors.163.com/centos/$releasever/centosplus/$basearch/
   gpgcheck=1
   enabled=0
   gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7

   或到http://mirrors.163.com/.help/centos.html下載對應版本的repo文件。