CentOS 安裝 Docker報錯信息：
問題: package docker-ce-3:19.03.2-3.el7.x86_64 requires containerd.io >= 1.2.2-3, but none of the providers can be installed
- cannot install the best candidate for the job
- 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
(try to add '--skip-broken' to skip uninstallable packages or '--nobest' to use not only best candidate packages)
檢查發現containerd.io此軟件包已經安裝，但版本是1.2.0；所以造成這種安裝失敗的原因是containerd.io軟件包版本過低
解決方法：
1.檢查Docker版本，安裝低版本，不進行安裝新版本Docker（在此就不繁瑣介紹低版本的安裝過程了）
[root@localhost ~]# yum list docker-ce --showduplicates | sort -r //檢查相應的軟件包版本
[root@localhost ~]# yum -y install docker-ce-18.06.0.ce-3.el7 //安裝低版本的軟件包
