DOCKER学习_010:Docker的文件系统以及制作镜像

一文件系统简介

1.1 Linux文件系统

LInux空间组成分为内核空间和用户空间（使用rootfs）

linux文件系统由 bootes和 rootfs组成， bootes主要包含boot1 oader和 kernel， bootloader主要是引导加载 kernel，当 kernel被加载到内存之后 boots就被卸载掉了。 rootfs包含的就是典型1inux系统中的/dev，/proc，/bin，/etc等标准目录

对于docker，只是使用rootfs，因为bootfs是共享的

1.2 docker的base镜像

docker的Base镜像提供的是最小安装的linux发行版

1.3 镜像的分层结构

[root@docker-server3 ~]# docker pull nginx

Using default tag: latest

latest: Pulling from library/nginx

8ec398bc0356: Already exists

465560073b6f: Pull complete

f473f9fd0a8c: Pull complete                     #镜像的分层

Digest: sha256:b2d89d0a210398b4d1120b3e3a7672c16a4ba09c2c4a0395f18b9f7999b768f2

Status: Downloaded newer image for nginx:latest

docker.io/library/nginx:latest

最多不能超过128层，镜像只读，分层

容器就相当于在镜像上加了一个读写层，容器的销毁就是读写层的销毁

读写层的操作，主要基于两种方式：写时复制和用时分配。

dockers的存储驱动查看

[root@docker-server3 ~]# docker info

Client:

 Debug Mode: false

Server:

 Containers:

  Running:

  Paused:

  Stopped:

 Images:

 Server Version: 19.03.

 Storage Driver: overlay2      #存储驱动

  Backing Filesystem: xfs

  Supports d_type: true

  Native Overlay Diff: true

 Logging Driver: journald

 Cgroup Driver: cgroupfs

 Plugins:

  Volume: local

  Network: bridge host ipvlan macvlan null overlay

  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog

 Swarm: inactive

 Runtimes: runc

 Default Runtime: runc

 Init Binary: docker-init

 containerd version: b34a5c8af56e510852c35414db4c1f4fa6172339

 runc version: 3e425f80a8c931f88e6d94a8c831b9d5aa481657

 init version: fec3683

 Security Options:

  seccomp

   Profile: default

 Kernel Version: 3.10.-957.27..el7.x86_64

 Operating System: CentOS Linux  (Core)

 OSType: linux

 Architecture: x86_64

 CPUs:

 Total Memory: .777GiB

 Name: docker-server3

 ID: YB6S:6D3D:477B:5UMR:IEX2:2PBD:D6BI:GDYI:22MD:GWSX:4TBX:2LLS

 Docker Root Dir: /var/lib/docker

 Debug Mode: false

 Registry: https://index.docker.io/v1/

 Labels:

 Experimental: false

 Insecure Registries:

  127.0.0.0/

 Live Restore Enabled: false

WARNING: API is accessible on http://0.0.0.0:2375 without encryption.

         Access to the remote API is equivalent to root access on the host. Refer

         to the 'Docker daemon attack surface' section in the documentation for

         more information: https://docs.docker.com/engine/security/security/#docker-daemon-attack-surface

二 commit制作Docker镜像

2.1 下载基础镜像

[root@docker-server3 ~]# docker pull centos:7

: Pulling from library/centos

ab5ef0e58194: Pull complete

Digest: sha256:4a701376d03f6b39b8c2a8f4a8e499441b0d567f9ab9d58e4991de4472fb813c

Status: Downloaded newer image for centos:

docker.io/library/centos:

[root@docker-server3 ~]# docker run -it centos:7 /bin/bash

[root@20b4b48c4055 /]#

[root@docker-server3 ~]# docker ps -a

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

20b4b48c4055        centos:            "/bin/bash"          seconds ago      Up  seconds                           admiring_wilbur

[root@20b4b48c4055 /]# ps -ef|grep ssh

2.2 安装一个ssh服务

请参考https://www.cnblogs.com/zyxnhr/p/11809167.html

[root@20b4b48c4055 /]# ps -a

   PID TTY          TIME CMD

     pts/    :: sshd

     pts/    :: ps

2.3 修改root密码

[root@20b4b48c4055 /]# echo 123456|passwd --stdin root

2.4 从宿主机连接

[root@docker-server3 ~]# docker inspect 20b4b48c4055 |grep IP

"LinkLocalIPv6Address": "",

            "LinkLocalIPv6PrefixLen": ,

            "SecondaryIPAddresses": null,

            "SecondaryIPv6Addresses": null,

            "GlobalIPv6Address": "",

            "GlobalIPv6PrefixLen": ,

            "IPAddress": "192.168.0.2",

            "IPPrefixLen": ,

            "IPv6Gateway": "",

                    "IPAMConfig": null,

                    "IPAddress": "192.168.0.2",

                    "IPPrefixLen": ,

                    "IPv6Gateway": "",

                    "GlobalIPv6Address": "",

                    "GlobalIPv6PrefixLen": ,

[root@docker-server3 ~]# ssh root@192.168.0.2

The authenticity of host '192.168.0.2 (192.168.0.2)' can't be established.

ECDSA key fingerprint is SHA256:e+hudnmpzwhC6r++fc+Nsps/8f9jOKCjjErm79GPvak.

ECDSA key fingerprint is MD5:dd:5f::e8:5f:ed:3f:6b:dd:3f:cb::ca:cc:5d:ff.

Are you sure you want to continue connecting (yes/no)? yes

Warning: Permanently added '192.168.0.2' (ECDSA) to the list of known hosts.

root@192.168.0.2's password:123456

[root@20b4b48c4055 ~]#

连接进入

[root@20b4b48c4055 ~]# ps -a

   PID TTY          TIME CMD

     pts/    :: sshd

    pts/    :: ps
[root@20b4b48c4055 ~]# exit

2.5 向容器拷贝文件

[root@docker-server3 ~]# docker cp /etc/sysconfig/network-scripts/ifcfg-ens33 20b4b48c4055:/tmp/

[root@20b4b48c4055 /]# cat /tmp/ifcfg-ens33

TYPE="Ethernet"

PROXY_METHOD="none"

BROWSER_ONLY="no"

BOOTPROTO="static"

DEFROUTE="yes"

IPV4_FAILURE_FATAL="no"

IPV6INIT="yes"

IPV6_AUTOCONF="yes"

IPV6_DEFROUTE="yes"

IPV6_FAILURE_FATAL="no"

IPV6_ADDR_GEN_MODE="stable-privacy"

NAME="ens33"

UUID="be414379-7791-472c-9a0a-bf732fe9d484"

DEVICE="ens33"

ONBOOT="yes"

IPADDR=192.168.132.133

GATEWAY=192.168.132.2

2.6 安装vim

[root@20b4b48c4055 /]# yum -y install vim

2.7 创建镜像

[root@docker-server3 ~]# docker commit -m "install sshd and vim" 20b4b48c4055 openssh:v1.0

sha256:d98ba06569f3ed7c00e1371b71a0ab328bacd57f5717bb4066b425c7b12abc3a

[root@docker-server3 ~]# docker image ls

REPOSITORY                      TAG                 IMAGE ID            CREATED             SIZE

openssh                         v1.                d98ba06569f3         seconds ago      361MB

nginx                           latest              f7bb5701a33c         days ago          126MB

busybox                         latest              6d5fcfe5ff17         days ago          .22MB

hub.darren.com/library/alpine   3.7                 cc0abc535e36         days ago          .59MB

centos                                             5e35e350aded         weeks ago         203MB

三镜像的测试使用修改

3.1 使用刚创建的镜像，起一个容器

[root@docker-server3 ~]# docker run -it -d openssh:v1.0

d865deaee6e83724a76a5eae88d8e356b5fe7416b5a8dbf9e1a9dd077ed7731a

[root@docker-server3 ~]# docker ps -a

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

d865deaee6e8        openssh:v1.        "/bin/bash"          seconds ago      Up  seconds                           sleepy_feistel

20b4b48c4055        centos:            "/bin/bash"          minutes ago      Up  minutes                           admiring_wil

[root@docker-server3 ~]# docker inspect d865deaee6e8|grep IP

"LinkLocalIPv6Address": "",

            "LinkLocalIPv6PrefixLen": ,

            "SecondaryIPAddresses": null,

            "SecondaryIPv6Addresses": null,

            "GlobalIPv6Address": "",

            "GlobalIPv6PrefixLen": ,

            "IPAddress": "192.168.0.3",

            "IPPrefixLen": ,

            "IPv6Gateway": "",

                    "IPAMConfig": null,

                    "IPAddress": "192.168.0.3",

                    "IPPrefixLen": ,

                    "IPv6Gateway": "",

                    "GlobalIPv6Address": "",

                    "GlobalIPv6PrefixLen": ,

[root@docker-server3 ~]# docker exec -it d865deaee6e8 /bin/bash

[root@d865deaee6e8 /]# /usr/sbin/sshd -D

3.2 测试连接

[root@docker-server3 ~]# ssh root@192.168.0.3

The authenticity of host '192.168.0.3 (192.168.0.3)' can't be established.

ECDSA key fingerprint is SHA256:e+hudnmpzwhC6r++fc+Nsps/8f9jOKCjjErm79GPvak.

ECDSA key fingerprint is MD5:dd:5f::e8:5f:ed:3f:6b:dd:3f:cb::ca:cc:5d:ff.

Are you sure you want to continue connecting (yes/no)? yes

Warning: Permanently added '192.168.0.3' (ECDSA) to the list of known hosts.

root@192.168.0.3's password:123456

3.3 检验容器内容

[root@d865deaee6e8 ~]# cat /tmp/ifcfg-ens33

TYPE="Ethernet"

PROXY_METHOD="none"

BROWSER_ONLY="no"

BOOTPROTO="static"

DEFROUTE="yes"

IPV4_FAILURE_FATAL="no"

IPV6INIT="yes"

IPV6_AUTOCONF="yes"

IPV6_DEFROUTE="yes"

IPV6_FAILURE_FATAL="no"

IPV6_ADDR_GEN_MODE="stable-privacy"

NAME="ens33"

UUID="be414379-7791-472c-9a0a-bf732fe9d484"

DEVICE="ens33"

ONBOOT="yes"

IPADDR=192.168.132.133

GATEWAY=192.168.132.2

[root@d865deaee6e8 ~]# rpm -qa|grep vim

vim-minimal-7.4.-.el7.x86_64

vim-common-7.4.-.el7.x86_64

vim-enhanced-7.4.-.el7.x86_64

vim-filesystem-7.4.-.el7.x86_64

[root@d865deaee6e8 ~]# rpm -qa|grep openssh

openssh-.4p1-.el7.x86_64

openssh-server-.4p1-.el7.x86_64

3.4 修改容器的默认前台进程

容器的默认主进程是PID问1的主进程，所以刚才的镜像在启动后，主进程是/bin/bash

[root@20b4b48c4055 /]# ps -ef

root                   : pts/    :: /bin/bash

root                  : pts/    :: /usr/sbin/sshd -D

root                 : pts/    :: ps -ef

需要再启动之前，使用/usr/sbin/sshd -D 替换/bin/bash

[root@docker-server3 ~]# docker run -it -d openssh:v1.0 /usr/sbin/sshd -D

[root@docker-server3 ~]# docker ps -a

CONTAINER ID        IMAGE               COMMAND               CREATED             STATUS              PORTS               NAMES

395c705716a5        openssh:v1.        "/usr/sbin/sshd -D"    seconds ago      Up  seconds                           laughing_edison

d865deaee6e8        openssh:v1.        "/bin/bash"            minutes ago      Up  minutes                           sleepy_feistel

20b4b48c4055        centos:            "/bin/bash"            minutes ago      Up  minutes                           admiring_w

[root@docker-server3 ~]# docker inspect 395c705716a5|grep IP

            "LinkLocalIPv6Address": "",

            "LinkLocalIPv6PrefixLen": ,

            "SecondaryIPAddresses": null,

            "SecondaryIPv6Addresses": null,

            "GlobalIPv6Address": "",

            "GlobalIPv6PrefixLen": ,

            "IPAddress": "192.168.0.4",

            "IPPrefixLen": ,

            "IPv6Gateway": "",

                    "IPAMConfig": null,

                    "IPAddress": "192.168.0.4",

                    "IPPrefixLen": ,

                    "IPv6Gateway": "",

                    "GlobalIPv6Address": "",

                    "GlobalIPv6PrefixLen": ,

[root@docker-server3 ~]# ssh root@192.168.0.4

The authenticity of host '192.168.0.4 (192.168.0.4)' can't be established.

ECDSA key fingerprint is SHA256:e+hudnmpzwhC6r++fc+Nsps/8f9jOKCjjErm79GPvak.

ECDSA key fingerprint is MD5:dd:5f::e8:5f:ed:3f:6b:dd:3f:cb::ca:cc:5d:ff.

Are you sure you want to continue connecting (yes/no)? yes

Warning: Permanently added '192.168.0.4' (ECDSA) to the list of known hosts.

root@192.168.0.4's password:

Last login: Tue Dec  ::  from gateway

[root@395c705716a5 ~]# ps -ef

UID         PID   PPID  C STIME TTY          TIME CMD

root          1      0  0 17:41 pts/0    00:00:00 /usr/sbin/sshd -D

root                   : ?        :: sshd: root@pts/

root                   : pts/    :: -bash

root                  : pts/    :: ps -ef

3.5 修改镜像

因为这个容器的PID为1的进程是/usr/sbin/sshd -D，在这个容器的基础上，制作一个新的镜像，让这个镜像的容器的默认前台进程为/usr/sbin/sshd -D

[root@docker-server3 ~]# docker commit -m "new default front process" 395c705716a5 openssh:v1.2

[root@docker-server3 ~]# docker image ls　　

REPOSITORY                      TAG                 IMAGE ID            CREATED             SIZE

openssh                         v1.                c399a750ed03         seconds ago       361MB

openssh                         v1.                d98ba06569f3         minutes ago      361MB

nginx                           latest              f7bb5701a33c         days ago          126MB

busybox                         latest              6d5fcfe5ff17         days ago          .22MB

hub.darren.com/library/alpine   3.7                 cc0abc535e36         days ago          .59MB

centos

3.7 测试检验

[root@docker-server3 ~]# docker run -d openssh:v1.2

08359e84c3a1f1cfe3742ba9a2348719ca9818e3d56c5817fbde70c31e27f714

[root@docker-server3 ~]# docker ps -a

CONTAINER ID        IMAGE               COMMAND               CREATED             STATUS              PORTS               NAMES

08359e84c3a1        openssh:v1.        "/usr/sbin/sshd -D"    seconds ago       Up  seconds                            intelligent_williams

395c705716a5        openssh:v1.        "/usr/sbin/sshd -D"    minutes ago      Up  minutes                           laughing_edison

d865deaee6e8        openssh:v1.        "/bin/bash"            minutes ago      Up  minutes                           sleepy_feistel

20b4b48c4055        centos:            "/bin/bash"            minutes ago      Up  minutes                           admiring_wilbur

[root@docker-server3 ~]# docker inspect 08359e84c3a1|grep IP

"LinkLocalIPv6Address": "",

            "LinkLocalIPv6PrefixLen": ,

            "SecondaryIPAddresses": null,

            "SecondaryIPv6Addresses": null,

            "GlobalIPv6Address": "",

            "GlobalIPv6PrefixLen": ,

            "IPAddress": "192.168.0.5",

            "IPPrefixLen": ,

            "IPv6Gateway": "",

                    "IPAMConfig": null,

                    "IPAddress": "192.168.0.5",

                    "IPPrefixLen": ,

                    "IPv6Gateway": "",

                    "GlobalIPv6Address": "",

                    "GlobalIPv6PrefixLen": ,

[root@docker-server3 ~]# ssh root@192.168.0.5

The authenticity of host '192.168.0.5 (192.168.0.5)' can't be established.

ECDSA key fingerprint is SHA256:e+hudnmpzwhC6r++fc+Nsps/8f9jOKCjjErm79GPvak.

ECDSA key fingerprint is MD5:dd:5f::e8:5f:ed:3f:6b:dd:3f:cb::ca:cc:5d:ff.

Are you sure you want to continue connecting (yes/no)? yes

Warning: Permanently added '192.168.0.5' (ECDSA) to the list of known hosts.

root@192.168.0.5's password:

Last login: Tue Dec  ::  from gateway

[root@08359e84c3a1 ~]# ps -ef

UID         PID   PPID  C STIME TTY          TIME CMD

root                   : ?        :: /usr/sbin/sshd -D

root                   : ?        :: sshd: root@pts/

root                   : pts/    :: -bash

root                  : pts/    :: ps -ef

博主声明：本文的内容来源主要来自誉天教育晏威老师，由本人实验完成操作验证，需要的博友请联系誉天教育（http://www.yutianedu.com/），获得官方同意或者晏老师（https://www.cnblogs.com/breezey/）本人同意即可转载，谢谢！