1、卸载老版本的Docker，没有安装则不卸载。
yum remove docker docker-client docker-client-latest docker-common docker-latest docker-latest-logrotate docker-logrotate docker-selinux docker-engine-selinux docker-engine
配置官方yum源，启用稳定版源配置。
[root@ChatDevOps-01 ~]# echo '[docker-ce-stable] name=Docker CE Stable - $basearch baseurl=https://download.docker.com/linux/CentOS/7/$basearch/stable enabled=1 gpgcheck=1 gpgkey=https://download.docker.com/linux/centos/gpg
[docker-ce-stable-debuginfo] name=Docker CE Stable - Debuginfo $basearch baseurl=https://download.docker.com/linux/centos/7/debug-$basearch/stable enabled=0 gpgcheck=1 gpgkey=https://download.docker.com/linux/centos/gpg
[docker-ce-stable-source] name=Docker CE Stable - Sources baseurl=https://download.docker.com/linux/centos/7/source/stable enabled=0 gpgcheck=1 gpgkey=https://download.docker.com/linux/centos/gpg
[docker-ce-edge] name=Docker CE Edge - $basearch baseurl=https://download.docker.com/linux/centos/7/$basearch/edge enabled=0 gpgcheck=1 gpgkey=https://download.docker.com/linux/centos/gpg
[docker-ce-edge-debuginfo] name=Docker CE Edge - Debuginfo $basearch baseurl=https://download.docker.com/linux/centos/7/debug-$basearch/edge enabled=0 gpgcheck=1 gpgkey=https://download.docker.com/linux/centos/gpg
[docker-ce-edge-source] name=Docker CE Edge - Sources baseurl=https://download.docker.com/linux/centos/7/source/edge enabled=0 gpgcheck=1 gpgkey=https://download.docker.com/linux/centos/gpg
[docker-ce-test] name=Docker CE Test - $basearch baseurl=https://download.docker.com/linux/centos/7/$basearch/test enabled=0 gpgcheck=1 gpgkey=https://download.docker.com/linux/centos/gpg
[docker-ce-test-debuginfo] name=Docker CE Test - Debuginfo $basearch baseurl=https://download.docker.com/linux/centos/7/debug-$basearch/test enabled=0 gpgcheck=1 gpgkey=https://download.docker.com/linux/centos/gpg
[docker-ce-test-source] name=Docker CE Test - Sources baseurl=https://download.docker.com/linux/centos/7/source/test enabled=0 gpgcheck=1 gpgkey=https://download.docker.com/linux/centos/gpg
[docker-ce-nightly] name=Docker CE Nightly - $basearch baseurl=https://download.docker.com/linux/centos/7/$basearch/nightly enabled=0 gpgcheck=1 gpgkey=https://download.docker.com/linux/centos/gpg
[docker-ce-nightly-debuginfo] name=Docker CE Nightly - Debuginfo $basearch baseurl=https://download.docker.com/linux/centos/7/debug-$basearch/nightly enabled=0 gpgcheck=1 gpgkey=https://download.docker.com/linux/centos/gpg
[docker-ce-nightly-source] name=Docker CE Nightly - Sources baseurl=https://download.docker.com/linux/centos/7/source/nightly enabled=0 gpgcheck=1 gpgkey=https://download.docker.com/linux/centos/gpg'>/etc/yum.repos.d/docker-ce.repo
此步骤中，需要注意的是：要启用哪个版本的源就将其下的enable值设置为1，其余设置为0。命令中的引号必须使用单引号。yum.repos.d目录下的文件必须以.repo结尾。
查看当前源的可用版本。
[root@ChatDevOps-01 ~]# yum list docker-ce --showduplicates|grep "^doc"|sort -r docker-ce.x86_64 18.06.1.ce-3.el7 docker-ce-stable docker-ce.x86_64 18.06.0.ce-3.el7 docker-ce-stable docker-ce.x86_64 18.03.1.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 18.03.0.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.12.1.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.12.0.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.09.1.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.09.0.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.06.2.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.06.1.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.06.0.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.03.3.ce-1.el7 docker-ce-stable docker-ce.x86_64 17.03.2.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.03.1.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.03.0.ce-1.el7.centos docker-ce-stable
安装docker-ce-18.06.0.ce-3.el7。若要安装其他版本则按照以下格式进行安装：docker-ce-
[root@ChatDevOps-01 ~]# yum -y install docker-ce-18.06.0.ce-3.el7 [root@ChatDevOps-01 ~]# docker version Client: Version: 18.06.0-ce API version: 1.38 Go version: go1.10.3 Git commit: 0ffa825 Built: Wed Jul 18 19:08:18 2018 OS/Arch: linux/amd64 Experimental: false Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?
启动docker服务。
[root@ChatDevOps-01 ~]# systemctl status docker ● docker.service - Docker Application Container Engine Loaded: loaded (/usr/lib/systemd/system/docker.service; disabled; vendor preset: disabled) Active: inactive (dead) Docs: https://docs.docker.com 12345 [root@ChatDevOps-01 ~]# systemctl start docker [root@ChatDevOps-01 ~]# docker version Client: Version: 18.06.0-ce API version: 1.38 Go version: go1.10.3 Git commit: 0ffa825 Built: Wed Jul 18 19:08:18 2018 OS/Arch: linux/amd64 Experimental: false
Server: Engine: Version: 18.06.0-ce API version: 1.38 (minimum version 1.12) Go version: go1.10.3 Git commit: 0ffa825 Built: Wed Jul 18 19:10:42 2018 OS/Arch: linux/amd64 Experimental: false
将docker服务设置为开机启动。
[root@ChatDevOps-01 ~]# systemctl enable docker Created symlink from /etc/systemd/system/multi-user.target.wants/docker.service to /usr/lib/systemd/system/docker.service.
参考资料： https://docs.docker.com/install/linux/docker-ce/centos/
