可見 docker.service 是依賴于 docker.socket 的，但是并不必要開啟
Tip: 其實上面的步驟完成，就已經能保證docker會開機啟動，原因是它依賴的 docker.socket 雖然本身設定為不要開機啟動，但開機時會被systemctl檢查然後觸發啟動以支援 docker.service 的運作
可以用上面方法也将 docker.socket 設為開機啟動(但這一步不是非常必要)
[root@h103 ~]# systemctl list-unit-files| grep docker
docker.service enabled
docker.socket disabled
[root@h103 ~]# systemctl enable docker.socket
Created symlink from /etc/systemd/system/sockets.target.wants/docker.socket to /usr/lib/systemd/system/docker.socket.
[root@h103 ~]# systemctl list-unit-files| grep docker
docker.service enabled
docker.socket enabled
[root@h103 ~]# 複制
解除安裝Docker
列出安裝包
[root@h103 ~]# yum list installed | grep docker
docker-engine.x86_64 1.9.1-1.el7.centos @dockerrepo
docker-engine-selinux.noarch 1.9.1-1.el7.centos @dockerrepo
[root@h103 ~]# 複制
删除軟體包
[root@h103 ~]# yum -y remove docker-engine.x86_64
Loaded plugins: fastestmirror, langpacks
Resolving Dependencies
--> Running transaction check
---> Package docker-engine.x86_64 0:1.9.1-1.el7.centos will be erased
--> Finished Dependency Resolution
Dependencies Resolved
======================================================================================================================================
Package Arch Version Repository Size
======================================================================================================================================
Removing:
docker-engine x86_64 1.9.1-1.el7.centos @dockerrepo 36 M
Transaction Summary
======================================================================================================================================
Remove 1 Package
Installed size: 36 M
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Erasing : docker-engine-1.9.1-1.el7.centos.x86_64 1/1
Verifying : docker-engine-1.9.1-1.el7.centos.x86_64 1/1
Removed:
docker-engine.x86_64 0:1.9.1-1.el7.centos
Complete!
[root@h103 ~]# 複制
這種情況下，隻删除了軟體包，但是沒有删除鏡像，容器，卷和自己建立的本地配置