docker简介

Docker提供了轻量级的虚拟化，它几乎没有任何额外开销，这非常的cool，相比于虚拟机，你可以在同一台机器上创建更多容器，而且启动docker容器只需要几秒钟，这是传统的虚拟机无法比拟的，这也是docker一经发布，就火爆互联网的原因，其应用场景非常广泛。

docker应用场景

docker运行用户

很多刚刚接触docker的朋友，基本都是用root进行管理docker容器，如下所示

[root@localhost ~]# docker ps -aCONTAINER ID        IMAGE                 COMMAND                  CREATED             STATUS                      PORTS               NAMESff668e421d59        mysql:5.7.28          "docker-entrypoint.s…"   38 hours ago        Exited (137) 10 hours ago                       mysql5.7.28_3307423e39a1c866        mysql:5.7.28          "docker-entrypoint.s…"   38 hours ago        Exited (137) 10 hours ago                       mysql5.7.28_330630482d5580fa        mysql:5.7.28          "docker-entrypoint.s…"   7 months ago        Exited (0) 46 hours ago                         mysql_dns_5.7.28669d7e9b8d4c        phensley/docker-dns   "./dockerdns --domai…"   7 months ago        Exited (2) 46 hours ago                         dnsb4f8d09ddf11        mysql:8.0.18          "docker-entrypoint.s…"   8 months ago        Exited (0) 10 days ago                          mysql8.0.18c8bc897479a9        mysql:5.7.28          "docker-entrypoint.s…"   8 months ago        Exited (0) 45 hours ago                         mysql5.7.28[root@localhost ~]# [root@localhost ~]# docker start ff668e421d59ff668e421d59[root@localhost ~]# [root@localhost ~]# docker psCONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                               NAMESff668e421d59        mysql:5.7.28        "docker-entrypoint.s…"   38 hours ago        Up 8 seconds        33060/tcp, 0.0.0.0:3307->3306/tcp   mysql5.7.28_3307[root@localhost ~]# 

用root管理容器，确实非常的方便，快捷，不过存在安全风险，因为root是操作系统的最高权限，docker容器运维人员用root权限，如果其账号丢失或者泄露，或者docker运维人员用root删除系统文件，就会造成严重后果，所以必须要做权限隔离。

那能用非root用户管理docker容器吗，答案是可以的。

非root用户管理容器

创建管理docker容器用户
由于docker软件安装好之后，自动会创建好docker用户组，所以这里只需要创建好管理docer容器的用户就好。

[root@localhost ~]# useradd -g docker -d /home/appdocker  appdocker [root@localhost ~]# [root@localhost ~]# id appdockeruid=2002(appdocker) gid=995(docker) 95(docker)

验证容器管理用户appdocker
先来看看用mysql用户来执行管理docker命令

[mysql@localhost ~]$ docker versionClient: Docker Engine - Community Version:           19.03.5 API version:       1.40 Go version:        go1.12.12 Git commit:        633a0ea Built:             Wed Nov 13 07:25:41 2019 OS/Arch:           linux/amd64 Experimental:      falseGot permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Get http://%2Fvar%2Frun%2Fdocker.sock/v1.40/version: dial unix /var/run/docker.sock: connect: permission denied[mysql@localhost ~]$ [mysql@localhost ~]$ docker psGot permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Get http://%2Fvar%2Frun%2Fdocker.sock/v1.40/containers/json: dial unix /var/run/docker.sock: connect: permission denied[mysql@localhost ~]$ 

可以看到用mysql用户执行docker version，docker ps都报错，无法访问/var/run/docker.sock
这个文件的。

来看看新创建的容器管理用户(appdocker)执行情况查看容器版本

[appdocker@localhost ~]$ docker versionClient: Docker Engine - Community Version:           19.03.5 API version:       1.40 Go version:        go1.12.12 Git commit:        633a0ea Built:             Wed Nov 13 07:25:41 2019 OS/Arch:           linux/amd64 Experimental:      falseServer: Docker Engine - Community Engine:  Version:          19.03.5  API version:      1.40 (minimum version 1.12)  Go version:       go1.12.12  Git commit:       633a0ea  Built:            Wed Nov 13 07:24:18 2019  OS/Arch:          linux/amd64  Experimental:     false containerd:  Version:          1.2.10  GitCommit:        b34a5c8af56e510852c35414db4c1f4fa6172339 runc:  Version:          1.0.0-rc8+dev  GitCommit:        3e425f80a8c931f88e6d94a8c831b9d5aa481657 docker-init:  Version:          0.18.0  GitCommit:        fec3683

查看正在运行的容器

[appdocker@localhost ~]$ docker psCONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                               NAMESff668e421d59        mysql:5.7.28        "docker-entrypoint.s…"   38 hours ago        Up 13 minutes       33060/tcp, 0.0.0.0:3307->3306/tcp   mysql5.7.28_3307[appdocker@localhost ~]$ 

启停容器

[appdocker@localhost ~]$ docker stop ff668e421d59ff668e421d59[appdocker@localhost ~]$ [appdocker@localhost ~]$ docker start ff668e421d59ff668e421d59[appdocker@localhost ~]$ docker psCONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                               NAMESff668e421d59        mysql:5.7.28        "docker-entrypoint.s…"   39 hours ago        Up 3 seconds        33060/tcp, 0.0.0.0:3307->3306/tcp   mysql5.7.28_3307[appdocker@localhost ~]$

可以看到已经新创建的用户appdocker可以完美的管理容器了。