Docker学习之3——容器

#创建容器
Usage:  docker create [OPTIONS] IMAGE [COMMAND] [ARG...]
#新建并启动容器
[root@controller ~]# docker run -t -i ubuntu:14.04 /bin/bash       
root@55456b431849:/# 
-t    分配一个伪终端
-i    标准输入保持打开
-d    守护进程运行
root@55456b431849:/# ls          
bin   dev  home  lib64  mnt  proc  run   srv  tmp  var
boot  etc  lib   media  opt  root  sbin  sys  usr
root@55456b431849:/# pwd
/
root@55456b431849:/# cat /etc/issue
Ubuntu 14.04.5 LTS \n \l
root@55456b431849:/# exit 
exit

#终止容器
Usage:  docker stop [OPTIONS] CONTAINER [CONTAINER...]
#查看处于终止状态的容器
[root@controller ~]# docker ps -a -q
f69ef742b752
be465c0dc442
55456b431849
#启动终止状态的容器
[root@controller ~]# docker start f69ef742b752

#进入容器
Usage:  docker attach [OPTIONS] CONTAINER
[root@controller ~]# docker run -idt ubuntu
[root@controller ~]# docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
cc9870d0853f        ubuntu              "/bin/bash"         22 seconds ago      Up 21 seconds                           small_albattani
[root@controller ~]# docker attach small_albattani
root@cc9870d0853f:/# 

Usage:  docker exec [OPTIONS] CONTAINER COMMAND [ARG...]
#一般情况下使用nsenter工具进入容器，安装工具
[root@controller ~]# yum install -y util-linux
[root@controller ~]# docker run --name dockercentos -tid centos
9f228b6525d5a753fbda39b4a339ae3f8de5f26d6d85a56c006488f771b4f45b
[root@controller ~]# docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
9f228b6525d5        centos              "/bin/bash"         10 seconds ago      Up 7 seconds                            dockercentos
[root@controller ~]# docker inspect -f "{{ .State.Pid }}"  dockercentos
85616
[root@controller ~]# nsenter -t 85616 -m -u -i -n -p     
[root@9f228b6525d5 /]# 

docker inspect -f {{.State.Pid}}容器名或者容器id
#每一个容器都有.State.Pid，所以这个命令除了容器的id需要我们根据docker ps -a去查找，其他的全部为固定的格式
nsenter --target上面查到的进程id --mount --uts --ipc --net --pid #输入该命令便进入到容器中

解释nsenter指令中进程id之后的参数的含义：

        * –mount参数是进去到mount namespace中
        * –uts参数是进入到uts namespace中
        * –ipc参数是进入到System V IPC namaspace中
        * –net参数是进入到network namespace中
        * –pid参数是进入到pid namespace中
        * –user参数是进入到user namespace中

我们可以写个脚本：
[root@controller ~]# cat IN_Docker.sh 
#!/bin/sh
if [ $# -ne 1 ]
        then
        echo $"usage:bash $0{dockername}"
        exit 1
fi
docker_in(){
NAME_ID=$1
PID=$(docker inspect -f "{{ .State.Pid }}" $NAME_ID)
nsenter -t $PID -m -u -i -n -p
}
docker_in $1
#运用
[root@controller ~]# sh IN_Docker.sh dockercentos
[root@9f228b6525d5 /]# 

#删除容器

docker rm -f 【NAMES】
[root@controller ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                      PORTS               NAMES
9f228b6525d5        centos              "/bin/bash"              18 minutes ago      Up 18 minutes                                   dockercentos
c5439518dcbe        ubuntu:14.04        "/bin/bash"              20 hours ago        Exited (0) 20 hours ago                         elegant_noyce
2bb8a93f5d34        ubuntu              "echo 'hello I am ubu"   23 hours ago        Exited (0) 19 hours ago                         gigantic_heyrovsky
[root@controller ~]# docker rm -f elegant_noyce
elegant_noyce
[root@controller ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                      PORTS               NAMES
9f228b6525d5        centos              "/bin/bash"              19 minutes ago      Up 19 minutes                                   dockercentos
2bb8a93f5d34        ubuntu              "echo 'hello I am ubu"   23 hours ago        Exited (0) 19 hours ago                         gigantic_heyrovsky

#导出容器
[root@controller ~]# docker export dockercentos >test_dockercentos.tar
[root@controller ~]# ls
192.168.128.172     cd1.iso                         httpd.conf     pike.install.sh  test_dockercentos.tar            web.yml
#导入容器
[root@controller ~]# cat test_dockercentos.tar |docker import - docker/cents7.4