搞了台VPS，想要装docker，发现死活装不上，各种报错。之前系统是centos6，发现官方现在已经不支持centos6了，遂升级到centos7，然后还是出现下面这个错误。

Error: Package: docker-engine-1.12.3-1.el7.centos.x86_64 (dockerrepo)

           Requires: systemd-units

Error: Package: docker-engine-1.12.3-1.el7.centos.x86_64 (dockerrepo)

           Requires: libseccomp.so.2()(64bit)

 You could try using --skip-broken to work around the problem

 You could try running: rpm -Va --nofiles --nodigest  

经过折腾一翻，已经解决了。

解决方案

1. 下载docker的仓库源wget https://download.docker.com/linux/centos/7/x86_64/stable/Packages/docker-ce-selinux-17.03.2.ce-1.el7.centos.noarch.rpm
2. 下载docker rpm包 wget https://download.docker.com/linux/centos/7/x86_64/stable/Packages/docker-ce-17.03.2.ce-1.el7.centos.x86_64.rpm
3. 安装仓库源 sudo yum install docker-ce-selinux-17.03.2.ce-1.el7.centos.noarch.rpm
4. 安装docker-ce sudo yum install docker-ce-17.03.2.ce-1.el7.centos.x86_64.rpm
5. 启动docker服务 service docker start
6. 解决！

其它参考资料

1. 官方软件仓库 https://download.docker.com/linux/centos/7/x86_64/stable/Packages/
2. centos 6下安装docker方法 https://www.cnblogs.com/skyrim/p/7712556.html