Use the CentOS7 ISO image as the Yum installation source

Step 1: Load ISO
Create an ISO mount directory mkdir/mnt/cdrom
Mount ISO to/mnt/cdrom mount-t iso9660/dev/cdrom/mnt/cdrom

Step 2: Configure the local Yum source
Create configuration file Touch Centos-iso.repo
The write configuration reads as follows
[Base]
name=centos-$releasever-base
#mirrorlist =http://mirrorlist.centos.org/?release= $releasever &arch= $basearch &repo=os&infra= $infra
Baseurl=file:///mnt/cdrom
Enabled=1
Gpgcheck=0
Gpgkey=file:///mnt/cdrom/rpm-gpg/rpm-gpg-key-centos-7

Finally, execute the following command:

Yum Clean All

Yum Update all