报错信息：file /usr/bin/kubectl from install of kubectl-1.17.4-0.x86_64 confliccts with file from package kubernetes-clients-1.5.2-0.7.git269f928.el7.x86_64
安装过其他版本或包，卸载掉再装就好了
yum remove kubernetes-client-1.5.2-0.7.git269f928.el7.x86_64
再重新安装：
yum install -y kubeadm
Installed:
kubeadm.x86_64 0:1.14.2-0
Dependency Installed:
cri-tools.x86_64 0:1.12.0-0 kubectl.x86_64 0:1.14.2-0 kubelet.x86_64 0:1.14.2-0 kubernetes-cni.x86_64 0:0.7.5-0
Complete!