yum install -y httpd
You have enabled checking of packages via GPG keys. This is a good thing
However, you do not have any GPG public keys installed. You need to download
the keys for packages you wish to install and install them.
You can do that by running the command:
rpm --import public.gpg.key
For more information contact your distribution or package provider.
解决方法 导入 gpg.key
用 rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY 导入 一般情况下
GPG KEY,一般系统都会有的,在你的linux安装光盘目录下，或者在/etc/pki/rpm-gpg/目录下有一个RPM-GPG-KEY-redhat-release
如果导入失败 那么 可已将GPG.KEY路径直接加入到你编辑的/etc/yum.repos.d/下的rhel7.repo 保存退出
然后 yum clean all
yum list 就ok了
再次试一下安装 yum install -y httpd
启动服务systemctl start httpd
查看服务是否开启 systemctl status httpd
runing'....
来源：https://www.cnblogs.com/goon2016vv/p/5625240.html