解决Centos7安装docker源问题

根据官方文档：https://docs.docker.com/install/linux/docker-ce/centos/搭建docker 

1.卸载docker旧版本：

sudo yum remove docker \
                  docker-client \
                  docker-client-latest \
                  docker-common \
                  docker-latest \
                  docker-latest-logrotate \
                  docker-logrotate \
                  docker-selinux \
                  docker-engine-selinux \
                  docker-engine\

2.安装相关工具类：

sudo yum install -y yum-utils \ device-mapper-persistent-data \ lvm2

3.配置docker仓库：

sudo yum-config-manager \ --add-repo \ https://download.docker.com/linux/centos/docker-ce.repo

会报以下错误： Loaded plugins: fastestmirror adding repo from: https://download.docker.com/linux/centos/docker-ce.repo grabbing file https://download.docker.com/linux/centos/docker-ce.repo to /etc/yum.repos.d/docker-ce.repo Could not fetch/save url https://download.docker.com/linux/centos/docker-ce.repo to file /etc/yum.repos.d/docker-ce.repo : [Errno 14] curl#35 - "TCP connection reset by peer

这是由于国内访问不到docker官方镜像的缘故 
可以通过aliyun的源来完成：

sudo yum-config-manager --add-repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

出现以下内容则表示docker仓库配置成功：

Loaded plugins: fastestmirror adding repo from: http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo grabbing file http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo to /etc/yum.repos.d/docker-ce.repo repo saved to /etc/yum.repos.d/docker-ce.repo

4.安装docker

sudo yum install docker-ce

出现以下异常：
Loaded plugins: fastestmirror
base
https://download-stage.docker.com/linux/centos/7/x86_64/stable/repodata/repomd.xml: [Errno 14] curl#35 - "TCP connection reset by peer"
Trying other mirror.
 One of the configured repositories failed (Docker CE Stable - x86_64),
 and yum doesn't have enough cached data to continue. At this point the only
 safe thing yum can do is fail. There are a few ways to work "fix" this:

     1. Contact the upstream for the repository and get them to fix the problem.

     2. Reconfigure the baseurl/etc. for the repository, to point to a working
        upstream. This is most often useful if you are using a newer
        distribution release than is supported by the repository (and the
        packages for the previous distribution release still work).

     3. Run the command with the repository temporarily disabled
            yum --disablerepo=docker-ce-stable ...

     4. Disable the repository permanently, so yum won't use it by default. Yum
        will then just ignore the repository until you permanently enable it
        again or use --enablerepo for temporary usage:

            yum-config-manager --disable docker-ce-stable
        or
            subscription-manager repos --disable=docker-ce-stable

     5. Configure the failing repository to be skipped, if it is unavailable.
        Note that yum will try to contact the repo. when it runs most commands,
        so will have to try and fail each time (and thus. yum will be be much
        slower). If it is a very temporary problem though, this is often a nice
        compromise:

            yum-config-manager --save --setopt=docker-ce-stable.skip_if_unavailable=true

failure: repodata/repomd.xml from docker-ce-stable: [Errno 256] No more mirrors to try.
https://download-stage.docker.com/linux/centos/7/x86_64/stable/repodata/repomd.xml: [Errno 14] curl#35 - "TCP connection reset by peer"

[root@localhost yum.repos.d]# systemctl restart docker 
[root@localhost yum.repos.d]# systemctl status docker