【Docker】Docker学习③ - Docker镜像管理

三、Docker镜像管理

• Docker镜像含有启动容器所需的文件系统及所需要的内容，因此镜像主要用于创建并启动docker容器。
• Docker镜像里面是一层层文件系统，叫做Union FS（联合文件系统），联合文件系统可以将几层目录挂载到一起，形成一个虚拟文件系统，虚拟文件系统的目录结构就像普通linux的目录结构一样，docker通过这些文件再加上宿主机的内核提供了一个linux的虚拟环境，每一层文件系统我们叫做layer，连恶化文件系统可以对每一层文件系统设置三种权限，只读（readonly）、读写（readwrite）和写出（whiteout-able），但是docker镜像中每一层文件系统都是只读的，构建镜像的时候，从一个最基本的操作系统开始，每个构建的操作都相当于做一层的修改，增加了一层文件系统，一层层往上叠加，上层的修改会覆盖底层该位置的可见性，这也很容易理解，就像上层把底层遮住了一样，当使用镜像的时候，我们只会看到一个完全的整体，不知道里面有几层也不需要知道里面有几层，结构如下：
  一个典型的linux文件系统由bootfs和rootfs两部分组成。
  • bootfs（boot file system）主要包含bootloader和kernel ，bootloader主要用于加载kernel，当kernel被加载到内存中后bootfs会被umount掉。
  • rootfs（root file system）包含的就是典型Linux系统中的 /dev,/proc,/bin,/etc 等标准目录和文件。
• 对于docker镜像通常都比较小，官方提供的centos基础镜像在200MB左右，一些其他版本的镜像甚至只有几MB，docker镜像直接调用宿主机的内核，镜像中只提供rootfs，也就是只需要包括最基本的命令、工具和程序库就可以了，比如alpine镜像，在5MB左右。

1. 搜索镜像

在官方的docker仓库中搜索指定名称的docker镜像，也会有很多三方镜像。
docker search centos:7.2.1511 #带指定版本号
docker search centos #不带版本号默认latest

2. 下载镜像

从docker仓库将镜像下载到本地

	docker pull 仓库服务器:端口/项目名称/镜像名称:tag(版本)号
	docker pull alpine
	docker pull nginx
	docker pull hello-world
	docker pull centos

3. 查看本地镜像

下载完成的镜像比下载的大，因为下载完成后会解压

	docker images
	REPOSITORY #镜像所属的仓库名称
	TAG        #镜像版本号（标识符），默认为latest
	IMAGE ID   #镜像唯一ID标识
	CREATED    #镜像创建的时间
	VIRTUAL SIZE #镜像的大小

4. 镜像导出

可以将镜像从本地导出为一个压缩文件，然后复制到其他服务器进行导入使用
导出方法1：

		docker save centos -o /opt/centos.tar.gz
		ll /opt/centos.tar.gz

导出方法2:

		docker save centos > /opt/centos-1.tar.gz
		ll /opt/centos-1.tar.gz
	    查看镜像内容：
		tar xvf centos.tar.gz
		cat manifest.json   #包含了镜像的相关配置，配置文件、分层
		[root@gbase8c_private opt]# cat manifest.json 
		[{"Config":"5d0da3dc976460b72c77d94c8a1ad043720b0416bfc16c52c45d4847e53fadb6.json","RepoTags":["centos:latest"],"Layers":["079bc5e75545bf45253ab44ce73fbd51d96fa52ee799031e60b65a82e89df662/layer.tar"]}]
		#分层为了方便文件的使用，即相同的文件可以共用

5. 镜像导入

	docker load < /opt/centos.tar.gz
	[root@gbase8c_1 opt]# docker images
	REPOSITORY   TAG       IMAGE ID   CREATED   SIZE
	[root@gbase8c_1 opt]# docker load < /opt/centos.tar.gz
	74ddd0ec08fa: Loading layer [==================================================>]  238.6MB/238.6MB
	Loaded image: centos:latest

验证镜像：

	docker images
	[root@gbase8c_1 opt]# docker images
	REPOSITORY   TAG       IMAGE ID       CREATED       SIZE
	centos       latest    5d0da3dc9764   2 years ago   231MB

6. 删除镜像

docker rmi centos
日志：

	[root@gbase8c_private opt]# docker images
	REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
	alpine              latest              8ca4688f4f35        7 weeks ago         7.34MB
	nginx               latest              605c77e624dd        23 months ago       141MB
	hello-world         latest              feb5d9fea6a5        2 years ago         13.3kB
	centos              latest              5d0da3dc9764        2 years ago         231MB
	[root@gbase8c_private opt]# docker rmi centos
	Untagged: centos:latest
	Untagged: centos@sha256:a27fd8080b517143cbbbab9dfb7c8571c40d67d534bbdee55bd6c473f432b177
	Deleted: sha256:5d0da3dc976460b72c77d94c8a1ad043720b0416bfc16c52c45d4847e53fadb6
	Deleted: sha256:74ddd0ec08fa43d09f32636ba91a0a3053b02cb4627c35051aff89f853606b59
	[root@gbase8c_private opt]# docker images
	REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
	alpine              latest              8ca4688f4f35        7 weeks ago         7.34MB
	nginx               latest              605c77e624dd        23 months ago       141MB
	hello-world         latest              feb5d9fea6a5        2 years ago         13.3kB

7. 容器操作基础命令

命令格式：

	#docker run [选项] [镜像名] [shell命令] [参数]
	#docker run [参数选项] [镜像名称，必须在所有选项的后面] [/bin/echo/ 'hello world'] #单次执行，没有自定义容器名称
	#docker run centos /bin/echo 'hello world' #启动的容器在执行完shell命令就退出了

7.1 从镜像启动一个容器

会直接进入到容器，并随机生成容器ID和名称
docker run -it docker.io/centos bash
#退出容器不注销
ctrl+p+q

7.2 显示正在运行的容器

docker ps

7.3 显示所有容器

包括当前正在运行以及以及关闭的所有容器
docker ps -a
[root@gbase8c_private ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED              STATUS                          PORTS               NAMES
7d6158088cbd        centos              "bash"              About a minute ago   Up About a minute                                   loving_mcnulty
e3e5fc354a71        hello-world         "/hello"            About a minute ago   Exited (0) About a minute ago                       determined_mayer

7.4 删除运行中的容器

即使容器正在运行当中，也会被强制删除掉
docker rm -f id
[root@gbase8c_private ~]# docker rm -f 7d6158088cbd
7d6158088cbd
[root@gbase8c_private ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                     PORTS               NAMES
e3e5fc354a71        hello-world         "/hello"            2 minutes ago       Exited (0) 2 minutes ago                       determined_mayer

7.5 随机映射端口

docker pull nginx #下载nginx 镜像
docker run -P docker.io/nginx #前台启动并随机映射本地端口到容器的80

前台启动的会话窗口无法进行其他操作，除非退出，但是退出后容器也会退出
随机端口映射，其实是默认从32768开始

	[root@gbase8c_private ~]# docker run -P docker.io/nginx
	/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
	/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
	/docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
	10-listen-on-ipv6-by-default.sh: info: Getting the checksum of /etc/nginx/conf.d/default.conf
	10-listen-on-ipv6-by-default.sh: info: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
	/docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
	/docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
	/docker-entrypoint.sh: Configuration complete; ready for start up
	2023/11/21 11:43:14 [notice] 1#1: using the "epoll" event method
	2023/11/21 11:43:14 [notice] 1#1: nginx/1.21.5
	2023/11/21 11:43:14 [notice] 1#1: built by gcc 10.2.1 20210110 (Debian 10.2.1-6) 
	2023/11/21 11:43:14 [notice] 1#1: OS: Linux 3.10.0-1160.71.1.el7.x86_64
	2023/11/21 11:43:14 [notice] 1#1: getrlimit(RLIMIT_NOFILE): 1048576:1048576
	2023/11/21 11:43:14 [notice] 1#1: start worker processes
	2023/11/21 11:43:14 [notice] 1#1: start worker process 29
	2023/11/21 11:43:14 [notice] 1#1: start worker process 30
	
	[root@gbase8c_private ~]# ss -nlt  | grep 32
	LISTEN     0      128       [::]:32768                 [::]:*   
	[root@gbase8c_private ~]# lsof -i:32768
	COMMAND     PID USER   FD   TYPE  DEVICE SIZE/OFF NODE NAME
	docker-pr 18312 root    4u  IPv6 1918183      0t0  TCP *:filenet-tms (LISTEN)

7.6 指定端口映射

• 方式一：本地端口81映射到容器80端口

	docker run -d -p 81:80 --name nginx-test-port1 nginx

• 方式二：本地IP:本地端口:容器端口

	docker run -d -p 192.168.56.199:82:80 --name nginx-test-port2 docker.io/nginx

• 方式三：本地IP:本地随机端口:容器端口

	docker run -d -p 192.168.56.199::80 --name nginx-test-port3 docker.io/nginx

• 方式四：本机IP:本地端口:容器端口/协议,默认为TCP协议

	docker run -d -p 192.168.56.199:83:80/udp --name nginx-test-port4 docker.io/nginx

• 方式五：一次性映射多个端口＋协议

	docker run -d -p 86:80/tcp  -p 443:443/tcp -p 54:54/udp --name nginx-test-port5 docker.io/nginx

• 查看运行的容器：

	[root@gbase8c_private ~]# docker ps -a
	CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                    PORTS                                                          NAMES
	e98563df7763        nginx               "/docker-entrypoint.…"   31 seconds ago      Up 30 seconds             0.0.0.0:54->54/udp, 0.0.0.0:443->443/tcp, 0.0.0.0:86->80/tcp   nginx-test-port5
	d906beba9990        nginx               "/docker-entrypoint.…"   2 minutes ago       Up 2 minutes              80/tcp, 192.168.56.199:83->80/udp                              nginx-test-port4
	3a11ac02e895        nginx               "/docker-entrypoint.…"   2 minutes ago       Up 2 minutes              192.168.56.199:32768->80/tcp                                   nginx-test-port3
	8af8fc6162d8        nginx               "/docker-entrypoint.…"   3 minutes ago       Up 3 minutes              192.168.56.199:82->80/tcp                                      nginx-test-port2
	6f9517d4c2d6        nginx               "/docker-entrypoint.…"   3 minutes ago       Up 3 minutes              0.0.0.0:81->80/tcp                                             nginx-test-port1

• 查看Nginx容器访问日志：

	docker logs nginx-test-port3
	docker logs -f nginx-test-port3

7.7 查看容器已经映射的端口

docker port nginx-test-port5
日志：

	[root@gbase8c_private ~]# docker port nginx-test-port5
	443/tcp -> 0.0.0.0:443
	54/udp -> 0.0.0.0:54
	80/tcp -> 0.0.0.0:86

7.8 自定义容器名称

	docker run -it --name nginx-test nginx

7.9 后台启动容器

	docker run -d -P --name nginx-test1 docker.io/nginx
	docker run -d --name centos-test1 docker.io/centos

	[root@gbase8c_private ~]# docker run -d --name centos-test1 docker.io/centos
	e5ff3cdb2754c37f706e29dd4be5a37e755e46889cada528562def7798899af2

7.10 创建并进入容器

创建容器后直接进入，执行exit退出后容器关闭

	docker run -t -i --name test-centos2 docker.io/centos /bin/bash

日志：

	[root@gbase8c_private ~]# docker run -t -i --name test-centos2 docker.io/centos /bin/bash
	[root@5cb9c84e7d17 /]# ps -aux
	USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
	root         1  1.2  0.0  12036  2108 pts/0    Ss   01:55   0:00 /bin/bash
	root        13  0.0  0.0  47572  2060 pts/0    R+   01:55   0:00 ps -aux

7.11 单次运行

容器退出后自动删除

	docker run -it --rm --name nginx-delete-test docker.io/nginx
	日志在4.7.13

7.12 传递运行命令

容器需要有一个前台运行的进程才能保持容器的运行，通过传递运行参数是一种方式，另外一可以在构建镜像的时候指定容器启动时运行的前台命令。
docker run -d centos /usr/bin/tail -f ‘/etc/hosts’
日志：

[root@gbase8c_private ~]# docker run -d centos /usr/bin/tail -f '/etc/hosts'
	74c0f99166085629ed7c488769505a7c35c9a98f96962594593ff0cc8960485d
	[root@gbase8c_private ~]# docker ps
	CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                                                          NAMES
	74c0f9916608        centos              "/usr/bin/tail -f /e…"   3 seconds ago       Up 3 seconds                                                                       competent_jepsen
	bd16c6917a24        nginx               "/docker-entrypoint.…"   4 minutes ago       Up 4 minutes        80/tcp                                                         nginx-delete-test1

7.13 容器的启动和关闭

docker stop 容器ID
docker start 容器ID
日志:

	[root@gbase8c_private ~]# docker ps
	CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                                                          NAMES
	74c0f9916608        centos              "/usr/bin/tail -f /e…"   3 seconds ago       Up 3 seconds                                                                       competent_jepsen
	bd16c6917a24        nginx               "/docker-entrypoint.…"   4 minutes ago       Up 4 minutes        80/tcp                                                         nginx-delete-test1
	c844e569456f        nginx               "/docker-entrypoint.…"   4 minutes ago       Up 4 minutes        80/tcp                                                         nginx-delete-test
	e98563df7763        nginx               "/docker-entrypoint.…"   18 minutes ago      Up 18 minutes       0.0.0.0:54->54/udp, 0.0.0.0:443->443/tcp, 0.0.0.0:86->80/tcp   nginx-test-port5
	d906beba9990        nginx               "/docker-entrypoint.…"   20 minutes ago      Up 20 minutes       80/tcp, 192.168.56.199:83->80/udp                              nginx-test-port4
	3a11ac02e895        nginx               "/docker-entrypoint.…"   20 minutes ago      Up 20 minutes       192.168.56.199:32768->80/tcp                                   nginx-test-port3
	8af8fc6162d8        nginx               "/docker-entrypoint.…"   20 minutes ago      Up 20 minutes       192.168.56.199:82->80/tcp                                      nginx-test-port2
	6f9517d4c2d6        nginx               "/docker-entrypoint.…"   21 minutes ago      Up 21 minutes       0.0.0.0:81->80/tcp                                             nginx-test-port1
	[root@gbase8c_private ~]# docker stop bd16c6917a24
	bd16c6917a24
	[root@gbase8c_private ~]# docker ps
	CONTAINER ID        IMAGE               COMMAND                  CREATED              STATUS              PORTS                                                          NAMES
	74c0f9916608        centos              "/usr/bin/tail -f /e…"   About a minute ago   Up About a minute                                                                  competent_jepsen
	c844e569456f        nginx               "/docker-entrypoint.…"   5 minutes ago        Up 5 minutes        80/tcp                                                         nginx-delete-test
	e98563df7763        nginx               "/docker-entrypoint.…"   19 minutes ago       Up 19 minutes       0.0.0.0:54->54/udp, 0.0.0.0:443->443/tcp, 0.0.0.0:86->80/tcp   nginx-test-port5
	d906beba9990        nginx               "/docker-entrypoint.…"   21 minutes ago       Up 21 minutes       80/tcp, 192.168.56.199:83->80/udp                              nginx-test-port4
	3a11ac02e895        nginx               "/docker-entrypoint.…"   21 minutes ago       Up 21 minutes       192.168.56.199:32768->80/tcp                                   nginx-test-port3
	8af8fc6162d8        nginx               "/docker-entrypoint.…"   22 minutes ago       Up 22 minutes       192.168.56.199:82->80/tcp                                      nginx-test-port2
	6f9517d4c2d6        nginx               "/docker-entrypoint.…"   22 minutes ago       Up 22 minutes       0.0.0.0:81->80/tcp                                             nginx-test-port1
	[root@gbase8c_private ~]# docker start bd16c6917a24
	Error response from daemon: No such container: bd16c6917a24
	Error: failed to start containers: bd16c6917a24
	[root@gbase8c_private ~]# docker stop 74c0f9916608
	74c0f9916608
	[root@gbase8c_private ~]# docker ps
	CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                                                          NAMES
	c844e569456f        nginx               "/docker-entrypoint.…"   6 minutes ago       Up 6 minutes        80/tcp                                                         nginx-delete-test
	e98563df7763        nginx               "/docker-entrypoint.…"   19 minutes ago      Up 19 minutes       0.0.0.0:54->54/udp, 0.0.0.0:443->443/tcp, 0.0.0.0:86->80/tcp   nginx-test-port5
	d906beba9990        nginx               "/docker-entrypoint.…"   22 minutes ago      Up 22 minutes       80/tcp, 192.168.56.199:83->80/udp                              nginx-test-port4
	3a11ac02e895        nginx               "/docker-entrypoint.…"   22 minutes ago      Up 22 minutes       192.168.56.199:32768->80/tcp                                   nginx-test-port3
	8af8fc6162d8        nginx               "/docker-entrypoint.…"   22 minutes ago      Up 22 minutes       192.168.56.199:82->80/tcp                                      nginx-test-port2
	6f9517d4c2d6        nginx               "/docker-entrypoint.…"   23 minutes ago      Up 23 minutes       0.0.0.0:81->80/tcp                                             nginx-test-port1
	[root@gbase8c_private ~]# docker ps -a
	CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                        PORTS                                                          NAMES
	74c0f9916608        centos              "/usr/bin/tail -f /e…"   2 minutes ago       Exited (137) 11 seconds ago                                                                  competent_jepsen
	c844e569456f        nginx               "/docker-entrypoint.…"   6 minutes ago       Up 6 minutes                  80/tcp                                                         nginx-delete-test
	e5ff3cdb2754        centos              "/bin/bash"              7 minutes ago       Exited (0) 7 minutes ago                                                                     centos-test1
	5cb9c84e7d17        centos              "/bin/bash"              11 minutes ago      Exited (130) 7 minutes ago                                                                   test-centos2
	264f9bd66c3f        nginx               "/docker-entrypoint.…"   15 minutes ago      Exited (0) 15 minutes ago                                                                    nginx-test
	e98563df7763        nginx               "/docker-entrypoint.…"   20 minutes ago      Up 20 minutes                 0.0.0.0:54->54/udp, 0.0.0.0:443->443/tcp, 0.0.0.0:86->80/tcp   nginx-test-port5
	d906beba9990        nginx               "/docker-entrypoint.…"   22 minutes ago      Up 22 minutes                 80/tcp, 192.168.56.199:83->80/udp                              nginx-test-port4
	3a11ac02e895        nginx               "/docker-entrypoint.…"   22 minutes ago      Up 22 minutes                 192.168.56.199:32768->80/tcp                                   nginx-test-port3
	8af8fc6162d8        nginx               "/docker-entrypoint.…"   22 minutes ago      Up 22 minutes                 192.168.56.199:82->80/tcp                                      nginx-test-port2
	6f9517d4c2d6        nginx               "/docker-entrypoint.…"   23 minutes ago      Up 23 minutes                 0.0.0.0:81->80/tcp                                             nginx-test-port1
	5f5d8410b29a        nginx               "/docker-entrypoint.…"   14 hours ago        Exited (0) 14 hours ago                                                                      musing_wozniak
	e3e5fc354a71        hello-world         "/hello"                 15 hours ago        Exited (0) 15 hours ago                                                                      determined_mayer
	[root@gbase8c_private ~]# docker start 74c0f9916608
	74c0f9916608
	[root@gbase8c_private ~]# docker ps
	CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                                                          NAMES
	74c0f9916608        centos              "/usr/bin/tail -f /e…"   2 minutes ago       Up 5 seconds                                                                       competent_jepsen
	c844e569456f        nginx               "/docker-entrypoint.…"   7 minutes ago       Up 7 minutes        80/tcp                                                         nginx-delete-test
	e98563df7763        nginx               "/docker-entrypoint.…"   21 minutes ago      Up 20 minutes       0.0.0.0:54->54/udp, 0.0.0.0:443->443/tcp, 0.0.0.0:86->80/tcp   nginx-test-port5
	d906beba9990        nginx               "/docker-entrypoint.…"   23 minutes ago      Up 23 minutes       80/tcp, 192.168.56.199:83->80/udp                              nginx-test-port4
	3a11ac02e895        nginx               "/docker-entrypoint.…"   23 minutes ago      Up 23 minutes       192.168.56.199:32768->80/tcp                                   nginx-test-port3
	8af8fc6162d8        nginx               "/docker-entrypoint.…"   23 minutes ago      Up 23 minutes       192.168.56.199:82->80/tcp                                      nginx-test-port2
	6f9517d4c2d6        nginx               "/docker-entrypoint.…"   24 minutes ago      Up 24 minutes       0.0.0.0:81->80/tcp                                             nginx-test-port1

7.14 进入到正在运行的容器

• 7.14.1 使用attach命令
  使用方式为docker attact 容器名，attach类似于vnc，操作会在各个容器界面显示，所有使用此方式进入容器的操作都是同步显示的且exit后容器将被关闭，且使用exit退出后容器关闭，不推荐使用，需要进入到有shell环境的容器，比如centos为例：

docker run -it centos centos bash

• 7.14.2 使用exec命令
  执行单次命令进入容器，不是很推荐此方式，虽然exit退出容器还在运行。
  docker exec -it centos-test3 /bin/bash
  日志：

	[root@gbase8c_private ~]# docker run --name centos-test3 -itd docker.io/centos /bin/bash
	46d17824678e24c8642e9e782e21c556b041889192733869c9dba2f50c120347
	[root@gbase8c_private ~]# docker ps -a
	CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                    PORTS               NAMES
	46d17824678e        centos              "/bin/bash"              5 seconds ago       Up 4 seconds                                  centos-test3
	[root@gbase8c_private ~]# docker exec -it centos-test3 /bin/bash
	[root@46d17824678e /]# ls
	bin  etc   lib	  lost+found  mnt  proc  run   srv  tmp  var
	dev  home  lib64  media       opt  root  sbin  sys  usr
	[root@46d17824678e /]# exit
	exit
	[root@gbase8c_private ~]# docker ps
	CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
	46d17824678e        centos              "/bin/bash"         49 seconds ago      Up 49 seconds                           centos-test3

• 7.14.3 使用nsenter命令
  推荐使用此方式，nsenter命令需要通过PID进入到容器内部，不过可以使用docker inspect获取到容器的PID

    yum install util-linux #安装nsenter命令
	docker inspect -f "{{.NetworkSettings.IPAddress}}" 46d17824678e 
	docker inspect -f "{{.State.Pid}}" mydocker #获取到某个docker容器的PID，可以通过PID进入到容器内
	docker inspect -f "{{.State.Pid}}" centos-test3
	nsenter -t PID -m -u -i -n -p

日志：

	[root@gbase8c_private ~]# docker inspect -f "{{.NetworkSettings.IPAddress}}" 46d17824678e 
	172.17.0.2
	[root@gbase8c_private ~]# docker inspect -f "{{.State.Pid}}" centos-test3
	8645
	[root@gbase8c_private ~]# nsenter -t 8645 -m -u -i -n -p
	[root@46d17824678e /]# ls
	bin  dev  etc  home  lib  lib64  lost+found  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var

• 7.14.4 脚本方式
  测试脚本是否可以正常进入到容器且退出后仍然正常运行

     chmod a+x docker-in.sh
	./docker-in.sh centos-test3

日志：

	[root@gbase8c_private docker]# cat docker-in.sh
	#!/bin/bash
	docker_in(){
		NAME_ID=$1
		PID=$(docker inspect -f "{{.State.Pid}}" ${NAME_ID})
		nsenter -t ${PID} -m -u -i -n -p
	}
	docker_in $1
	
	[root@gbase8c_private docker]# ./docker-in.sh centos-test3
	[root@46d17824678e /]# pwd
	/
	[root@46d17824678e /]# exit
	logout
	[root@gbase8c_private docker]# ./docker-in.sh centos-test3
	[root@46d17824678e /]# exit
	logout

7.15 查看容器内部的hosts文件

默认会将实例的ID添加到自己的hosts文件
日志：

	[root@gbase8c_private docker]# docker run -it --name test-centos3 docker.io/centos /bin/bash
	[root@cccb2108056e /]# cat /etc/hosts
	127.0.0.1	localhost
	::1	localhost ip6-localhost ip6-loopback
	fe00::0	ip6-localnet
	ff00::0	ip6-mcastprefix
	ff02::1	ip6-allnodes
	ff02::2	ip6-allrouters
	172.17.0.3	cccb2108056e  

	#ping 容器ID
	[root@cccb2108056e /]# ping cccb2108056e
	PING cccb2108056e (172.17.0.3) 56(84) bytes of data.
	64 bytes from cccb2108056e (172.17.0.3): icmp_seq=1 ttl=64 time=0.029 ms
	64 bytes from cccb2108056e (172.17.0.3): icmp_seq=2 ttl=64 time=0.037 ms
	64 bytes from cccb2108056e (172.17.0.3): icmp_seq=3 ttl=64 time=0.034 ms
	^C
	--- cccb2108056e ping statistics ---
	3 packets transmitted, 3 received, 0% packet loss, time 2007ms
	rtt min/avg/max/mdev = 0.029/0.033/0.037/0.005 ms

7.16 批量关闭正在运行的容器

docker stop $(docker ps -a -q) #正常关闭所有运行中的容器
日志：

	[root@gbase8c_private docker]# docker stop $(docker ps -a -q)
	cccb2108056e
	46d17824678e

7.17 批量强制关闭正在运行中的容器

docker kill $(docker ps -a -q)
日志：

	[root@gbase8c_private docker]# docker kill $(docker ps -a -q)
	Error response from daemon: Cannot kill container: cccb2108056e: Container cccb2108056e5fea630892d67139ad6ee2bfa666f9d0eae738ff8c5d34984d29 is not running
	[root@gbase8c_private docker]# docker start cccb2108056e
	cccb2108056e
	[root@gbase8c_private docker]# docker kill $(docker ps -a -q)
	cccb2108056e

7.18 批量删除已退出容器

docker rm -f docker ps -aq -f status=exited
日志：

	[root@gbase8c_private docker]# docker rm -f `docker ps -aq -f status=exited`
	cccb2108056e

7.19 批量删除所有容器

docker rm -f $(docker ps -a -q)
日志：

	[root@gbase8c_private docker]# docker run -itd --name centos-test4 docker.io/centos /bin/bash 
	64bf39002c67ff9aded56780315a4a8c4639a3189d891cdd35092e1c203d4f6d
	[root@gbase8c_private docker]# docker rm -f $(docker ps -a -q)
	64bf39002c67
	261a6c2dd260

7.20 指定容器DNS

Dns服务，默认采用宿主机的dns地址
一是将dns地址配置在宿主机
二是将参数配置在docker启动脚本里面 -dns=1.1.1.1
docker run -it --rm --dns 223.6.6.6 centos bash
cat /etc/resolv.conf
日志：

	[root@gbase8c_private docker]# docker run -it --rm --dns 223.6.6.6 centos bash
	[root@c01a69476a06 /]# cat /etc/resolv.conf
	nameserver 223.6.6.6