# 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-$releasever - Base
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
baseurl=http://mirrors.ustc.edu.cn/centos-altarch/$releasever/os/$basearch/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-SIG-AltArch-Arm32
#released updates
[updates]
name=CentOS-$releasever - Updates
# mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
baseurl=http://mirrors.ustc.edu.cn/centos-altarch/$releasever/updates/$basearch/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-SIG-AltArch-Arm32
#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
# mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
baseurl=http://mirrors.ustc.edu.cn/centos-altarch/$releasever/extras/$basearch/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-SIG-AltArch-Arm32
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
# mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
baseurl=http://mirrors.ustc.edu.cn/centos-altarch/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-SIG-AltArch-Arm32
然后执行命令清空并生成缓存：
yum clean all
yum makecache
大功告成！
安装软件报错
报错如下：
GPG key retrieval failed: [Errno 14] curl#37 - "Couldn‘t open file /etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7"
解决方法①：
vim /etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7
-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: GnuPG v1.4.11 (GNU/Linux)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=hdPa
-----END PGP PUBLIC KEY BLOCK-----
解决方法②：
cd /etc/pki/rpm-gpg
wget https://archive.fedoraproject.org/pub/epel/RPM-GPG-KEY-EPEL-7