No packages marked for update

问题：用yum安装docker，更新yum存储时，报以下错误，导致yum坏了

[root@localhost yum.repos.d]# vi docker.repo
[root@localhost yum.repos.d]# yum update
Loaded plugins: fastestmirror, langpacks
base                                                     | 3.6 kB     00:00
dockerrepo                                               | 2.9 kB     00:00
extras                                                   | 3.4 kB     00:00
updates                                                  | 3.4 kB     00:00
dockerrepo/7/primary_db                                    |  34 kB   00:00
Loading mirror speeds from cached hostfile
 * base: mirrors.cn99.com
 * extras: mirrors.aliyun.com
 * updates: mirrors.cn99.com
No packages marked for update

解决方法：重新安装yum

[root@localhost ~]# rpm -qa|grep yum|xargs rpm -e --nodeps  
[root@localhost ~]# rpm -qa |grep yum 
[root@localhost ~]# wget http://centos.ustc.edu.cn/centos/7/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
[root@localhost ~]# wget http://centos.ustc.edu.cn/centos/7/os/x86_64/Packages/yum-3.4.3-154.el7.centos.noarch.rpm
[root@localhost ~]# wget http://centos.ustc.edu.cn/centos/7/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-42.el7.noarch.rpm
[root@localhost ~]# rpm -ivh yum-*
Preparing...                          ################################# [100%]
Updating / installing...
   1:yum-metadata-parser-1.1.4-10.el7 ################################# [ 33%]
   2:yum-plugin-fastestmirror-1.1.31-4################################# [ 67%]
   3:yum-3.4.3-154.el7.centos         ################################# [100%]
[root@localhost ~]# wget http://docs.linuxtone.org/soft/lemp/CentOS-Base.repo
[root@localhost ~]# yum makecache
Loaded plugins: fastestmirror
base                                                     | 3.6 kB     00:00
extras                                                   | 3.4 kB     00:00
updates                                                  | 3.4 kB     00:00
(1/8): extras/7/x86_64/other_db                            | 108 kB   00:00
(2/8): extras/7/x86_64/filelists_db                        | 636 kB   00:01
(3/8): updates/7/x86_64/prestodelta                        | 771 kB   00:01
(4/8): extras/7/x86_64/prestodelta                         | 102 kB   00:02
(5/8): updates/7/x86_64/other_db                           | 621 kB   00:00
(6/8): updates/7/x86_64/filelists_db                       | 3.5 MB   00:06
(7/8): base/7/x86_64/filelists_db                          | 6.7 MB   00:08
(8/8): base/7/x86_64/other_db                              | 2.5 MB   00:09
Loading mirror speeds from cached hostfile
 * base: mirrors.163.com
 * extras: mirrors.aliyun.com
 * updates: mirrors.cn99.com
Metadata Cache Created