CentOS8默认容器是Podman，目前部署k8s首选还是docker，所以需要先卸载Podman，再安装docker和k8s。
kuboard.cn上提供了极好用的k8s一键部署脚本，但是在CentOS8系统下会有报错：

错误：
 问题: package docker-ce-3:19.03.8-3.el7.x86_64 requires containerd.io >= 1.2.2-3, but none of the providers can be installed
  - conflicting requests
  - package containerd.io-1.2.10-3.2.el7.x86_64 is excluded
  - package containerd.io-1.2.13-3.1.el7.x86_64 is excluded
  - package containerd.io-1.2.2-3.3.el7.x86_64 is excluded
  - package containerd.io-1.2.2-3.el7.x86_64 is excluded
  - package containerd.io-1.2.4-3.1.el7.x86_64 is excluded
  - package containerd.io-1.2.5-3.1.el7.x86_64 is excluded
  - package containerd.io-1.2.6-3.3.el7.x86_64 is excluded
(尝试添加 '--skip-broken' 来跳过无法安装的软件包 或 '--nobest' 来不只使用最佳选择的软件包)

源里面的containerd.io版本太低，导致docker没有正确安装上去。还是手工安装containerd.io吧：

wget https://download.docker.com/linux/centos/7/x86_64/stable/Packages/containerd.io-1.2.6-3.3.el7.x86_64.rpm
dnf install containerd.io-1.2.6-3.3.el7.x86_64.rpm

装完之后再根据kuboard.cn上的手动安装部分的教程来继续后面的步骤，注意跳过卸载原油docker的步骤。