Docker容器学习梳理 - SSH方式登陆容器

时间:2022-08-17 14:20:53

 

前面几篇已经介绍了Docker基础环境的部署,下面介绍下通过ssh方式登陆Docker容器的操作记录(其实不太建议直接用ssh去连接上容器的想法,虽然可以,但是有很多弊端,而且docker已经提供了容器内执行的命令,没有必要再折腾每一个容器为sshd服务器。具体参考:http://jpetazzo.github.io/2014/06/23/docker-ssh-considered-evil/

[root@localhost ~]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
centos7             7.3.1611            d5ebea14da54        2 weeks ago         311 MB
<none>              <none>              d5c154b612c8        2 weeks ago         311 MB
test                latest              ecefde07358f        11 weeks ago        599.6 MB
learn/ping          latest              fea07d84b0df        4 months ago        196.7 MB
docker.io/tomcat    latest              ebb17717bed4        4 months ago        355.4 MB
docker.io/centos    latest              980e0e4c79ec        6 months ago        196.7 MB
nginx               1.9                 c8c29d842c09        9 months ago        182.7 MB
docker.io/redis     2.8.19              dd9fe7db5236        22 months ago       110.7 MB
 
[root@localhost ~]# docker run -i -t centos7:7.3.1611 /bin/bash
 
[root@a3c8baf6961e /]# cat /etc/redhat-release
CentOS Linux release 7.3.1611 (Core)
 
[root@a3c8baf6961e /]# yum install wget vim
[root@a3c8baf6961e /]# wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
 
安装ssh服务端
[root@a3c8baf6961e /]# yum cleal all
[root@a3c8baf6961e /]# yum install passwd
[root@a3c8baf6961e /]# yum install openssh-server 
 
修改容器密码(提前yum -y reinstall cracklib-dicts)
[root@a3c8baf6961e /]# echo "123456" |passwd --stdin root
 
产生公私钥
[root@a3c8baf6961e /]# ssh-keygen -t rsa     //一路回车
[root@a3c8baf6961e /]# cd ~/.ssh/
[root@a3c8baf6961e .ssh]# ls
id_rsa  id_rsa.pub
[root@a3c8baf6961e .ssh]# cp id_rsa.pub  authorized_keys
[root@a3c8baf6961e .ssh]# ls
authorized_keys  id_rsa  id_rsa.pub
 
执行sshd命令,有报错:
[root@a3c8baf6961e .ssh]# /usr/sbin/sshd
Could not load host key: /etc/ssh/ssh_host_rsa_key
Could not load host key: /etc/ssh/ssh_host_dsa_key
Could not load host key: /etc/ssh/ssh_host_ecdsa_key
Could not load host key: /etc/ssh/ssh_host_ed25519_key
 
解决办法:
[root@a3c8baf6961e .ssh]# ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key     //均是一路回车
[root@a3c8baf6961e .ssh]# ssh-keygen -t dsa -f /etc/ssh/ssh_host_dsa_key
[root@a3c8baf6961e .ssh]# ssh-keygen -t rsa -f /etc/ssh/ssh_host_ecdsa_key
[root@a3c8baf6961e .ssh]# ssh-keygen -t rsa -f /etc/ssh/ssh_host_ed25519_key
 
再次执行sshd命令,如果没有报错,说明可以启动了
[root@a3c8baf6961e .ssh]# /usr/sbin/sshd
[root@a3c8baf6961e .ssh]#

-----------------------启动ssh,如果报错如下(这是centos7下的一个bug)-------------------------
[root@a3c8baf6961e .ssh]# systemctl restart sshd.service
Failed to get D-Bus connection: Operation not permitted
这个报错在之前的文档里就已经提到过了
解决办法如下:
先把上面的容器关闭(docker stop container-id),然后重新启动容器,启动时加上参数--privileged(特权参数,也可以是--privileged=true,如果启动容器中挂载目录没有权限也可以添加此参数)和/sbin/init(代替/bin/bash),如下:
[root@localhost ~]#  docker run --privileged -i -t centos7:7.3.1611 /sbin/init       
上面的容器启动后,会一直在卡着的状态中,先不用管,打开另一个终端窗口,查看容器
[root@localhost ~]# docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS                     NAMES
af40bd07fa0f        centos7:7.3.1611    "/sbin/init"        28 seconds ago      Up 28 seconds                                 nauseous_shirley

然后按照容器的ID进去,这个时候再根据/bin/bash进入容器(前面加exec -it参数),接着重启ssh服务就ok了
[root@localhost ~]# docker exec -it af40bd07fa0f /bin/bash
[root@af40bd07fa0f /]# systemctl restart sshd.service
[root@af40bd07fa0f /]# echo "123456" |passwd --stdin root    //注意这里由于上述特殊情况重新启动了容器,之前创建的root密码无效了(这就相当于重新另起了一个容器),需要重新修改下root密码!!可以随便创建个用户,然后切换到root,测试下之前创建的root密码是否还有效!
--------------------------------------------------------------------------------------------------
查看ssh端口,发现22端口已经开启
[root@af40bd07fa0f /]# ss -a|grep ssh
tcp    LISTEN     0      128     *:ssh                   *:*                    
tcp    LISTEN     0      128    :::ssh                  :::*                    
[root@af40bd07fa0f /]# ss -ln|grep 22
u_dgr  UNCONN     0      0         * 26884224              * 26885412           
tcp    LISTEN     0      128       *:22                    *:*                  
tcp    LISTEN     0      128      :::22                   :::*  

然后docker ps查看下容器,提交更改为新镜像,运行新的镜像

[root@localhost ~]# docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS                     NAMES
af40bd07fa0f        centos7:7.3.1611    "/sbin/init"        21 minutes ago      Up 21 minutes                                 nauseous_shirley

记住这个容器ID,然后关闭
[root@localhost ~]# docker stop af40bd07fa0f
af40bd07fa0f 
接着提交改为新的镜像,使用上一步的容器ID,提交名为wangssh的镜像(提交成功后,之前创建的容器可以选择删除(docker ps -a 查看);当然不删除也不影响。建议不要删除,可以再次启用提交新的镜像以便他用。)
[root@localhost ~]# docker commit af40bd07fa0f wangssh
sha256:ca5e393b7605949e58c1067c1bc73d99d52f47107756f0ade1725ca04886fd71
[root@localhost ~]# 

提交成功后,使用docker images可以查看到
[root@localhost ~]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
wangssh             latest              ca5e393b7605        57 seconds ago      327.1 MB
centos7             7.3.1611            d5ebea14da54        2 weeks ago         311 MB

然后运行新的镜像
[root@localhost ~]# docker run -d -p 220:22 wangssh /usr/sbin/sshd -D
b0a845a3dedeac7b46002d1c8514077309d88dcc0667b7080bc1ab67d70eb167
docker: Error response from daemon: Cannot start container b0a845a3dedeac7b46002d1c8514077309d88dcc0667b7080bc1ab67d70eb167: [9] System error: SELinux policy denies access..
如上出现上面的报错,这是由于selinux造成的!需要关闭selinux,如下:
[root@localhost ~]# setenforce 0
[root@localhost ~]# getenforce 
Permissive

然后再次运行新的镜像,就成功了!
[root@localhost ~]# docker run -d -p 220:22 wangssh /usr/sbin/sshd -D
0a7c1406361ef52dcc5c32801e4c7c231078594cd7010375ea33fe3024cc9126
[root@localhost ~]# 
上面运行命令中的参数解释:
-d   后台运行容器
-p   容器端口映射到主机[可选]

使用docker ps查看运行的容器
[root@localhost ~]# docker ps
CONTAINER ID        IMAGE               COMMAND               CREATED              STATUS              PORTS                     NAMES
0a7c1406361e        wangssh             "/usr/sbin/sshd -D"   About a minute ago   Up About a minute   0.0.0.0:220->22/tcp       focused_hawking

此时你可以直接连接容器,也可以通过端口映射连接容器(使用之前创建的容器密码123456登陆)
[root@localhost ~]# ssh -p220 root@localhost
root@localhost's password:
[root@0a7c1406361e ~]#

------------------------------------------------------------------------------------------------------------------
如果要想做ssh无密码登陆的信任关系,只需要将物理机本地的~/.ssh/id_rsa.pub拷贝到容器里的~/.ssh/authorized_keys即可

接着上面ID为aea267757cc9的容器登陆后的操作:
[root@localhost ~]# docker exec -it aea267757cc9 /bin/bash
[root@aea267757cc9 /]# ssh-keygen -t rsa    //一路回车

将物理机本地的~/.ssh/id_rsa.pub拷贝到容器里
[root@localhost ~]# docker cp ~/.ssh/id_rsa.pub aea267757cc9:/root/.ssh/

然后到容器里将id_rsa.pub拷贝为authorized_keys
[root@aea267757cc9 /]# cd ~
[root@aea267757cc9 ~]# cd .ssh/
[root@aea267757cc9 .ssh]# cp id_rsa.pub authorized_keys

接着提交为新镜像
[root@localhost ~]# docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS                     NAMES
aea267757cc9        centos7:7.3.1611    "/sbin/init"        About an hour ago   Up 38 minutes                                 admiring_hodgkin
fc726a6a27d2        centos              "/bin/bash"         3 months ago        Up 3 months         0.0.0.0:32772->80/tcp     web1
9d99c7b9451b        centos              "/bin/bash"         3 months ago        Up 3 months         0.0.0.0:32769->8080/tcp   web3
[root@localhost ~]# docker stop aea267757cc9
aea267757cc9
[root@localhost ~]# docker commit aea267757cc9 hahassh
sha256:906bf1bd2a156b1222def7d3d21fbc2cd7e963fc923f5a6da92e6b45954688d9
[root@localhost ~]# setenforce 0
[root@localhost ~]# docker run -d -p 220:22 hahassh /usr/sbin/sshd -D
8b9c153463c73122cfd787a27190a8665f54fe77fa51601d521baab5a9234f2e

最后尝试ssh方式连接容器,发现可以无密码登陆了~
[root@localhost ~]# ssh -p220 root@localhost
Last login: Mon Mar 13 10:03:54 2017

---------------------------------------------------------------------------------------------------------------------
当登陆到容器后,可以查看下容器ip

第一种方式:
[root@localhost ~]# docker ps 
CONTAINER ID        IMAGE               COMMAND               CREATED             STATUS              PORTS                     NAMES
b220fabf815a        wangssh             "/usr/sbin/sshd -D"   6 hours ago         Up About an hour    0.0.0.0:20020->22/tcp     gigantic_goldwasser
fc726a6a27d2        980e0e4c79ec        "/bin/bash"           3 months ago        Up About an hour    0.0.0.0:32768->80/tcp     web1
9d99c7b9451b        980e0e4c79ec        "/bin/bash"           3 months ago        Up About an hour    0.0.0.0:32769->8080/tcp   web3
[root@localhost ~]# docker inspect b220fabf815a |grep IPAddress
            "SecondaryIPAddresses": null,
            "IPAddress": "172.17.0.2",
                    "IPAddress": "172.17.0.2",

第二种方式:
[root@localhost ~]# docker inspect --format='{{.NetworkSettings.IPAddress}}' b220fabf815a
172.17.0.2

第三种方式:
登陆到容器里使用“yum install net-tools”,安装后就可以使用ifconfig命令查看ip了  

当知道了容器的ip后,就可以使用ssh直接连接容器的22端口即可!
[root@localhost ~]# ssh 172.17.0.2
root@172.17.0.2's password: 
Last login: Tue Mar 14 09:11:27 2017 from 172.17.0.1
[root@b220fabf815a ~]#