centos salt安装

原来salt的源已经失效，最新安装方法如下：

#增加salt源
sudo rpm --import https://repo.saltproject.io/py3/redhat/7/x86_64/latest/SALTSTACK-GPG-KEY.pub
curl -fsSL https://repo.saltproject.io/py3/redhat/7/x86_64/latest.repo | sudo tee /etc/yum.repos.d/salt.repo

#安装salt agent
yum clean expire-cache
yum install salt-minion