作者yujin2010good·2018-12-03 15:40

系统工程师·大型零售巨头

docker学习三--镜像管理

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镜像是 Docker 的三大组件之一。
Docker 运行容器前需要本地存在对应的镜像，如果镜像不存在本地，Docker 会从镜像仓库下载（默认是
Docker Hub 公共注册服务器中的仓库）。

=====================

1、将容器变为镜像

docker commit <container> [repo:tag]
当我们在制作自己的镜像的时候，会在container中安装一些工具、修改配置，如果不做commit保存起来，那么container停止以后在启动，这些更改就消失了?

docker create --name myjava3 -it java /bin/bash
docker start myjava3
docker ps
docker exec -it ce36c9815ea6 /bin/bash

[root@ip-10-249-100-205 ~]# docker create --name myjava3 -it java /bin/bash
ce36c9815ea6fe1302b8237bbfd0a219c1a3b0c4bb3ad467d99c7ef9e8d14662
[root@ip-10-249-100-205 ~]# docker start myjava3
myjava3
[root@ip-10-249-100-205 ~]# docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                    NAMES
ce36c9815ea6        java                "/bin/bash"              18 seconds ago      Up 6 seconds                                 myjava3
1549052941a1        mysql               "docker-entrypoint.sh"   3 hours ago         Up 3 hours          0.0.0.0:3306->3306/tcp   mysqlsrv1
[root@ip-10-249-100-205 ~]# docker exec -it ce36c9815ea6 /bin/bash
root@ce36c9815ea6:/# ls
bin  boot  dev  etc  home  lib  lib64  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var
root@ce36c9815ea6:/# mkdir wolf
root@ce36c9815ea6:/# ls
bin  boot  dev  etc  home  lib  lib64  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var  wolf
root@ce36c9815ea6:/#

docker commit ce36c9815ea6 myjava
docker images
docker run -it myjava ls

[root@ip-10-249-100-205 ~]# docker commit ce36c9815ea6 myjava
[root@ip-10-249-100-205 ~]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
myjava              latest              2e503320c91d        27 seconds ago      643.1 MB
docker.io/mysql     latest              f008d8ff927d        3 weeks ago         408.5 MB
docker.io/java      latest              d23bdf5b1b1b        12 months ago       643.1 MB
sha256:2e503320c91da2198453a2684dea4049ac2cd6e6de38f5dd7d97c2c750f4a111
[root@ip-10-249-100-205 ~]# docker run -it myjava ls
bin   dev  home  lib64  mnt  proc  run   srv  tmp  var
boot  etc  lib   media  opt  root  sbin  sys  usr  wolf

这里发现很快就创建了一个新的容器

这种做法的优点：最方便、最快速
这种做法的缺点：不规范、无法自动化（完全手工）

=====================

2、buildfile语法和案例

在Dockerfile中用到的命令有

FROM
FROM指定一个基础镜像，一般情况下一个可用的 Dockerfile一定是 FROM 为第一个指令。至于image则可以是任何合理存在的image镜像。
FROM 一定是首个非注释指令 Dockerfile.
FROM 可以在一个 Dockerfile 中出现多次，以便于创建混合的images。
如果没有指定 tag ，latest 将会被指定为要使用的基础镜像版本。

MAINTAINER
这里是用于指定镜像制作者的信息

RUN
RUN命令将在当前image中执行任意合法命令并提交执行结果。命令执行提交后，就会自动执行Dockerfile中的下一个指令。
层级 RUN 指令和生成提交是符合Docker核心理念的做法。它允许像版本控制那样，在任意一个点，对image 镜像进行定制化构建。
RUN 指令缓存不会在下个命令执行时自动失效。比如 RUN apt-get dist-upgrade -y 的缓存就可能被用于下一个指令. --no-cache 标志可以被用于强制取消缓存使用。

ENV
ENV指令可以用于为docker容器设置环境变量
ENV设置的环境变量，可以使用 docker inspect命令来查看。同时还可以使用docker run --env <key>=<value>来修改环境变量。

USER
USER 用来切换运行属主身份的。Docker 默认是使用 root，但若不需要，建议切换使用者身分，毕竟 root 权限太大了，使用上有安全的风险。

WORKDIR
WORKDIR 用来切换工作目录的。Docker 默认的工作目录是/，只有 RUN 能执行 cd 命令切换目录，而且还只作用在当下下的 RUN，也就是说每一个 RUN 都是独立进行的。如果想让其他指令在指定的目录下执行，就得靠 WORKDIR。WORKDIR 动作的目录改变是持久的，不用每个指令前都使用一次 WORKDIR。

COPY
COPY 将文件从路径 <src> 复制添加到容器内部路径 <dest>。
<src> 必须是想对于源文件夹的一个文件或目录，也可以是一个远程的url，<dest> 是目标容器中的绝对路径。
所有的新文件和文件夹都会创建UID 和 GID 。事实上如果 <src> 是一个远程文件URL，那么目标文件的权限将会是600。

ADD
ADD 将文件从路径 <src> 复制添加到容器内部路径 <dest>。
<src> 必须是想对于源文件夹的一个文件或目录，也可以是一个远程的url。<dest> 是目标容器中的绝对路径。
所有的新文件和文件夹都会创建UID 和 GID。事实上如果 <src> 是一个远程文件URL，那么目标文件的权限将会是600。

VOLUME

创建一个可以从本地主机或其他容器挂载的挂载点，一般用来存放数据库和需要保持的数据等。

EXPOSE

EXPOSE 指令指定在docker允许时指定的端口进行转发。

CMD

Dockerfile.中只能有一个CMD指令。 如果你指定了多个，那么最后个CMD指令是生效的。
CMD指令的主要作用是提供默认的执行容器。这些默认值可以包括可执行文件，也可以省略可执行文件。
当你使用shell或exec格式时，  CMD 会自动执行这个命令。

ONBUILD

ONBUILD 的作用就是让指令延迟執行，延迟到下一个使用 FROM 的 Dockerfile 在建立 image 时执行，只限延迟一次。
ONBUILD 的使用情景是在建立镜像时取得最新的源码 (搭配 RUN) 与限定系统框架。

ARG

ARG是Docker1.9 版本才新加入的指令。
ARG 定义的变量只在建立 image 时有效，建立完成后变量就失效消失

LABEL

定义一个 image 标签 Owner，并赋值，其值为变量 Name 的值。(LABEL Owner=$Name )

ENTRYPOINT
是指定 Docker image 运行成 instance (也就是 Docker container) 时，要执行的命令或者文件。

下面是一个java镜像的buildfile

FROM nimmis/ubuntu:14.04
MAINTAINER nimmis <1098331428@qq.com>
# disable interactive functions
ENV DEBIAN_FRONTEND noninteractive
# set default java environment variable
RUN ./hello.sh
ENV JAVA_HOME /usr/lib/jvm/java-8-openjdk-amd64
RUN apt-get install -y software-properties-common && \\
add-apt-repository ppa:openjdk-r/ppa -y && \\
apt-get update && \\
apt-get install -y --no-install-recommends openjdk-8-jre && \\
rm -rf /var/lib/apt/lists/*

[root@ip-10-249-100-205 ~]# vi Dockerfile
FROM nimmis/ubuntu:14.04
MAINTAINER nimmis <1098331428@qq.com>
# disable interactive functions
ENV DEBIAN_FRONTEND noninteractive
# set default java environment variable
ENV JAVA_HOME /usr/lib/jvm/java-8-openjdk-amd64
RUN apt-get install -y software-properties-common && \\
add-apt-repository ppa:openjdk-r/ppa -y && \\
apt-get update && \\
apt-get install -y --no-install-recommends openjdk-8-jre && \\
rm -rf /var/lib/apt/lists/*

[root@ip-10-249-100-205 ~]# docker build -t leader/java .
Sending build context to Docker daemon 671.8 MB
Step 1 : FROM nimmis/ubuntu:14.04
Trying to pull repository docker.io/nimmis/ubuntu ... 
14.04: Pulling from docker.io/nimmis/ubuntu
c954d15f947c: Pull complete 
c3688624ef2b: Pull complete 
848fe4263b3b: Pull complete 
23b4459d3b04: Pull complete 
36ab3b56c8f1: Pull complete 
a846ffa8449f: Pull complete 
616db5a385dd: Pull complete 
Digest: sha256:79abf8801761e9ed573fd5d62a2d934b39b688053776a3e49a0ecce326ddaf9c
 ---> b7242adec142
Step 2 : MAINTAINER nimmis <1098331428@qq.com>
 ---> Running in 78f2d5a33afa
 ---> ae9e9e54813e
Removing intermediate container 78f2d5a33afa
Step 3 : ENV DEBIAN_FRONTEND noninteractive
 ---> Running in d19abcfab952
 ---> 6102ee29b5c9
Removing intermediate container d19abcfab952
Step 4 : ENV JAVA_HOME /usr/lib/jvm/java-8-openjdk-amd64
 ---> Running in 958a3f6abb4a
 ---> ccb9aec8aab7
Removing intermediate container 958a3f6abb4a
Step 5 : RUN apt-get install -y software-properties-common && add-apt-repository ppa:openjdk-r/ppa -y && apt-get update && apt-get install -y --no-install-recommends openjdk-8-jre && rm -rf /var/lib/apt/lists/*
 ---> Running in ce5ac07cdb7b
Reading package lists...
Building dependency tree...

[root@ip-10-249-100-205 ~]# docker images
REPOSITORY                TAG                 IMAGE ID            CREATED             SIZE
leader/java               latest              dd51ecfc4015        10 minutes ago      509.3 MB
myjava                    latest              2e503320c91d        44 minutes ago      643.1 MB
docker.io/nimmis/ubuntu   14.04               b7242adec142        13 days ago         346.4 MB
docker.io/mysql           latest              f008d8ff927d        3 weeks ago         408.5 MB
docker.io/java            latest              d23bdf5b1b1b        12 months ago       643.1 MB

[root@ip-10-249-100-205 ~]# vi Dockerfile 
FROM nimmis/ubuntu:14.04
MAINTAINER nimmis <1098331428@qq.com>
# disable interactive functions
ENV DEBIAN_FRONTEND noninteractive
# set default java environment variable
RUN ./hello.sh
ENV JAVA_HOME /usr/lib/jvm/java-8-openjdk-amd64
RUN apt-get install -y software-properties-common && \\
add-apt-repository ppa:openjdk-r/ppa -y && \\
apt-get update && \\
apt-get install -y --no-install-recommends openjdk-8-jre && \\
rm -rf /var/lib/apt/lists/*
[root@ip-10-249-100-205 ~]# docker build -t wolf .
Sending build context to Docker daemon 671.8 MB
Step 1 : FROM nimmis/ubuntu:14.04
 ---> b7242adec142
Step 2 : MAINTAINER nimmis <1098331428@qq.com>
 ---> Using cache
 ---> ae9e9e54813e
Step 3 : ENV DEBIAN_FRONTEND noninteractive
 ---> Using cache
 ---> 6102ee29b5c9
Step 4 : RUN ./hello.sh
 ---> Running in 12d20b190c16
/bin/sh: 1: ./hello.sh: not found
The command '/bin/sh -c ./hello.sh' returned a non-zero code: 127

[root@ip-10-249-100-205 ~]# vi Dockerfile 
FROM nimmis/ubuntu:14.04
MAINTAINER nimmis <1098331428@qq.com>
# disable interactive functions
ENV DEBIAN_FRONTEND noninteractive
# set default java environment variable
ADD hello.sh /bin/hello.sh
RUN /bin/hello.sh
ENV JAVA_HOME /usr/lib/jvm/java-8-openjdk-amd64
RUN apt-get install -y software-properties-common && \\
add-apt-repository ppa:openjdk-r/ppa -y && \\
apt-get update && \\
apt-get install -y --no-install-recommends openjdk-8-jre && \\
rm -rf /var/lib/apt/lists/*
~
[root@ip-10-249-100-205 ~]# docker build -t wolf .
Sending build context to Docker daemon 671.8 MB
Step 1 : FROM nimmis/ubuntu:14.04
 ---> b7242adec142
Step 2 : MAINTAINER nimmis <1098331428@qq.com>
 ---> Using cache
 ---> ae9e9e54813e
Step 3 : ENV DEBIAN_FRONTEND noninteractive
 ---> Using cache
 ---> 6102ee29b5c9
Step 4 : ADD hello.sh /bin/hello.sh
 ---> 66a47c44cc7d
Removing intermediate container 39f6eaa88e25
Step 5 : RUN /bin/hello.sh
 ---> Running in 0681f5d4e06d
hello world
 ---> 814f69156baa
Removing intermediate container 0681f5d4e06d
Step 6 : ENV JAVA_HOME /usr/lib/jvm/java-8-openjdk-amd64
 ---> Running in 910b9e1163ba

[root@ip-10-249-100-205 ~]# vi Dockerfile 
FROM nimmis/ubuntu:14.04
MAINTAINER nimmis <1098331428@qq.com>
# disable interactive functions
ENV DEBIAN_FRONTEND noninteractive
RUN curl http://baidu.com
# set default java environment variable
ADD hello.sh /bin/hello.sh
RUN /bin/hello.sh
ENV JAVA_HOME /usr/lib/jvm/java-8-openjdk-amd64
RUN apt-get install -y software-properties-common && \\
add-apt-repository ppa:openjdk-r/ppa -y && \\
apt-get update && \\
apt-get install -y --no-install-recommends openjdk-8-jre && \\
rm -rf /var/lib/apt/lists/*

[root@ip-10-249-100-205 ~]# docker build -t wolf .
Sending build context to Docker daemon 671.8 MB
Step 1 : FROM nimmis/ubuntu:14.04
 ---> b7242adec142
Step 2 : MAINTAINER nimmis <1098331428@qq.com>
 ---> Using cache
 ---> ae9e9e54813e
Step 3 : ENV DEBIAN_FRONTEND noninteractive
 ---> Using cache
 ---> 6102ee29b5c9
Step 4 : RUN curl http://baidu.com
 ---> Running in b9ec969e052b
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    81  100    81    0     0   4142      0 --:--:-- --:--:-- --:--:--  4263
<html>
<meta http-equiv="refresh" content="0;url=http://www.baidu.com/">
</html>
 ---> f92c8fde20db
Removing intermediate container b9ec969e052b

=====================
镜像制作中的常见问题
1、把ssh server是否应该包含到竞相里？密码是放到变量中，不安全，一些观点认为不适合把ssh server打包到镜像中。
2、一个容器究竟运行几个程序？一个容器运行一个程序比较好，当然这个没有绝对答案
3、程序参数和配置文件的问题？程序设计的问题。
4、程序log输出的问题？log通过vlom绑定的到本地磁盘写出到宿主主机，这样就可以监控log了。
5、docker友好程序架构

                          Etcd/zookeeper

docker image docker container docker container docker container

======================

1、查看images默认从官方下载

[root@i-r2irzkkd ~]# docker search hello-world
INDEX       NAME                                                DESCRIPTION                                     STARS     OFFICIAL   AUTOMATED
docker.io   docker.io/hello-world                               Hello World! (an example of minimal Docker...   159       [OK]       
docker.io   docker.io/tutum/hello-world                         Image to test docker deployments. Has Apac...   27                   [OK]
docker.io   docker.io/dockercloud/hello-world                   Hello World!                                    4                    [OK]
docker.io   docker.io/marcells/aspnet-hello-world               ASP.NET vNext - Hello World                     4                    [OK]
docker.io   docker.io/bonomat/nodejs-hello-world                a simple nodejs hello world container           2                    [OK]
docker.io   docker.io/carinamarina/hello-world-app              This is a sample Python web application, r...   1                    [OK]
docker.io   docker.io/carinamarina/hello-world-web              A Python web app, running on port 5000, wh...   1                    [OK]
docker.io   docker.io/mikespuborg/dockercloud-hello-world       Fix dockercloud-hello-world example for al...   1                    [OK]
docker.io   docker.io/neoxsys/hello-world                       hello-world container based on Ubuntu 16.0...   1                    [OK]
docker.io   docker.io/vegasbrianc/docker-hello-world                                                            1                    [OK]
docker.io   docker.io/yesimages/hello-world                     exercise java hello-world app                   1                    [OK]
docker.io   docker.io/brogency/hello-world                      simple docker hello world? app powered b...     0                    [OK]
docker.io   docker.io/crccheck/hello-world                      Hello World web server in under 2.5 MB          0                    [OK]
docker.io   docker.io/gscrivano/hello-world                     hello world example system container            0                    [OK]
docker.io   docker.io/helloworld314/hello-world-docker          Hello world docker                              0                    [OK]
docker.io   docker.io/hirotakakato/hello-world                  hello-world                                     0                    [OK]
docker.io   docker.io/mdzhang/docker-sinatra-hello-world        (WIP) Hello World web app using Docker, Si...   0                    [OK]
docker.io   docker.io/n8io/hello-world                          A simple hello world node.js app to test d...   0                    [OK]
docker.io   docker.io/navycloud/hello-world                     Navy hello world                                0                    [OK]
docker.io   docker.io/nirmata/hello-world                                                                       0                    [OK]
docker.io   docker.io/rcarun/hello-world                                                                        0                    [OK]
docker.io   docker.io/scottsbaldwin/docker-hello-world          A simple NGINX image, serving a single HTM...   0                    [OK]
docker.io   docker.io/waleedsamy/hello-world-expressjs-docker   Hello world express sample, return `Hello ...   0                    [OK]
docker.io   docker.io/wodge/docker-hello-world                  Hello World test for auto update to Docker...   0                    [OK]
docker.io   docker.io/wowgroup/hello-world                      Minimal web app for testing purposes            0                    [OK]
[root@i-r2irzkkd ~]# docker search centos
INDEX       NAME                                      DESCRIPTION                                     STARS     OFFICIAL   AUTOMATED
docker.io   docker.io/centos                          The official build of CentOS.                   2608      [OK]       
docker.io   docker.io/jdeathe/centos-ssh              CentOS-6 6.8 x86_64 / CentOS-7 7.2.1511 x8...   28                   [OK]
docker.io   docker.io/jdeathe/centos-ssh-apache-php   CentOS-6 6.8 x86_64 / Apache / PHP / PHP M...   18                   [OK]
docker.io   docker.io/nimmis/java-centos              This is docker images of CentOS 7 with dif...   14                   [OK]
docker.io   docker.io/million12/centos-supervisor     Base CentOS-7 with supervisord launcher, h...   12                   [OK]
docker.io   docker.io/jdeathe/centos-ssh-mysql        CentOS-6 6.8 x86_64 / MySQL.                    8                    [OK]
docker.io   docker.io/torusware/speedus-centos        Always updated official CentOS docker imag...   8                    [OK]
docker.io   docker.io/nickistre/centos-lamp           LAMP on centos setup                            4                    [OK]
docker.io   docker.io/centos/mariadb55-centos7                                                        3                    [OK]
docker.io   docker.io/nathonfowlie/centos-jre         Latest CentOS image with the JRE pre-insta...   3                    [OK]
docker.io   docker.io/consol/sakuli-centos-xfce       Sakuli end-2-end testing and monitoring co...   2                    [OK]
docker.io   docker.io/blacklabelops/centos            CentOS Base Image! Built and Updates Daily!     1                    [OK]
docker.io   docker.io/darksheer/centos                Base Centos Image -- Updated hourly             1                    [OK]
docker.io   docker.io/harisekhon/centos-java          Java on CentOS (OpenJDK, tags jre/jdk7-8)       1                    [OK]
docker.io   docker.io/timhughes/centos                Centos with systemd installed and running       1                    [OK]
docker.io   docker.io/dmglab/centos                   CentOS with some extras - This is for the ...   0                    [OK]
docker.io   docker.io/grayzone/centos                 auto build for centos.                          0                    [OK]
docker.io   docker.io/grossws/centos                  CentOS 6 and 7 base images with gosu and l...   0                    [OK]
docker.io   docker.io/harisekhon/centos-scala         Scala + CentOS (OpenJDK tags 2.10-jre7 - 2...   0                    [OK]
docker.io   docker.io/januswel/centos                 yum update-ed CentOS image                      0                    [OK]
docker.io   docker.io/kz8s/centos                     Official CentOS plus epel-release               0                    [OK]
docker.io   docker.io/labengine/centos                Centos image base                               0                    [OK]
docker.io   docker.io/repositoryjp/centos             Docker Image for CentOS.                        0                    [OK]
docker.io   docker.io/smartentry/centos               CentOS with smartentry                          0                    [OK]
docker.io   docker.io/ustclug/centos                   USTC centos                                    0                    [OK]

2、下载指定hello-world镜像

[root@i-r2irzkkd ~]# docker pull docker.io/hello-world
Using default tag: latest
Trying to pull repository docker.io/library/hello-world ... 
latest: Pulling from docker.io/library/hello-world
c04b14da8d14: Pull complete 
Digest: sha256:0256e8a36e2070f7bf2d0b0763dbabdd67798512411de4cdcf9431a1feb60fd9
Status: Downloaded newer image for docker.io/hello-world:latest

docker pull docker.io/hello-world,仓库地址，docker.io，没有指明tag，默认就是latest.运行这个镜像

3、查看images

[root@i-r2irzkkd ~]# docker images
REPOSITORY              TAG                 IMAGE ID            CREATED             SIZE
docker.io/centos        latest              970633036444        5 weeks ago         196.7 MB
docker.io/hello-world   latest              c54a2cc56cbb        9 weeks ago         1.848 kB

4、运行镜像

docker run docker.io/hello-world
docker run docker.io/centos
[root@i-r2irzkkd ~]# docker run docker.io/hello-world

Hello from Docker!
This message shows that your installation appears to be working correctly.

To generate this message, Docker took the following steps:
 1. The Docker client contacted the Docker daemon.
 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
 3. The Docker daemon created a new container from that image which runs the
    executable that produces the output you are currently reading.
 4. The Docker daemon streamed that output to the Docker client, which sent it
    to your terminal.

To try something more ambitious, you can run an Ubuntu container with:
 $ docker run -it ubuntu bash

Share images, automate workflows, and more with a free Docker Hub account:
 https://hub.docker.com

For more examples and ideas, visit:
 https://docs.docker.com/engine/userguide/

5、查看镜像信息

docker inspect 镜像名
[root@i-r2irzkkd ~]# docker images
REPOSITORY              TAG                 IMAGE ID            CREATED             SIZE
docker.io/centos        latest              970633036444        5 weeks ago         196.7 MB
docker.io/hello-world   latest              c54a2cc56cbb        9 weeks ago         1.848 kB

docker inspect docker.io/centos
docker inspect docker.io/hello-world
如下
[root@i-r2irzkkd ~]# docker inspect docker.io/centos
[
    {
        "Id": "sha256:97063303644439d9cea259b0e5f4b468633c90d88bf526acc67e5ae0a6e9427c",
        "RepoTags": [
            "docker.io/centos:latest"
        ],
        "RepoDigests": [],
        "Parent": "",
        "Comment": "",
        "Created": "2016-07-29T20:59:10.01570692Z",
        "Container": "53ef97a96c409a033e214be92d67d0682ecace7ae5155c647a80aea20fb8e375",
        "ContainerConfig": {
            "Hostname": "66388f647a9e",
            "Domainname": "",
            "User": "",
            "AttachStdin": false,
            "AttachStdout": false,
            "AttachStderr": false,
            "Tty": false,
            "OpenStdin": false,
            "StdinOnce": false,
            "Env": [
                "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
            ],
            "Cmd": [
                "/bin/sh",
                "-c",
                "#(nop) CMD [\\"/bin/bash\\"]"
            ],
            "Image": "sha256:f9cad40b5c05cdea07181c7404b12d5704a943e7cd8285ec791bb6962c07d5b8",
            "Volumes": null,
            "WorkingDir": "",
            "Entrypoint": null,
            "OnBuild": null,
            "Labels": {
                "build-date": "20160729",
                "license": "GPLv2",
                "name": "CentOS Base Image",
                "vendor": "CentOS"
            }
        },
        "DockerVersion": "1.10.3",
        "Author": "https://github.com/CentOS/sig-cloud-instance-images",
        "Config": {
            "Hostname": "66388f647a9e",
            "Domainname": "",
            "User": "",
            "AttachStdin": false,
            "AttachStdout": false,
            "AttachStderr": false,
            "Tty": false,
            "OpenStdin": false,
            "StdinOnce": false,
            "Env": [
                "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
            ],
            "Cmd": [
                "/bin/bash"
            ],
            "Image": "sha256:f9cad40b5c05cdea07181c7404b12d5704a943e7cd8285ec791bb6962c07d5b8",
            "Volumes": null,
            "WorkingDir": "",
            "Entrypoint": null,
            "OnBuild": null,
            "Labels": {
                "build-date": "20160729",
                "license": "GPLv2",
                "name": "CentOS Base Image",
                "vendor": "CentOS"
            }
        },
        "Architecture": "amd64",
        "Os": "linux",
        "Size": 196734860,
        "VirtualSize": 196734860,
        "GraphDriver": {
            "Name": "devicemapper",
            "Data": {
                "DeviceId": "2",
                "DeviceName": "docker-8:1-394772-d4653020ef51d99c9503416250a5cd9be7c12692a1c449a58a1ed6bf7cb8c330",
                "DeviceSize": "10737418240"
            }
        }
    }
]
[root@i-r2irzkkd ~]# docker inspect docker.io/hello-world
[
    {
        "Id": "sha256:c54a2cc56cbb2f04003c1cd4507e118af7c0d340fe7e2720f70976c4b75237dc",
        "RepoTags": [
            "docker.io/hello-world:latest"
        ],
        "RepoDigests": [],
        "Parent": "",
        "Comment": "",
        "Created": "2016-07-01T19:39:27.532838486Z",
        "Container": "562cadb4d17bbf30b58ab0f6a870be60c8d36d2e401bf637f1d2d7f8afbef666",
        "ContainerConfig": {
            "Hostname": "c65bc554a4b7",
            "Domainname": "",
            "User": "",
            "AttachStdin": false,
            "AttachStdout": false,
            "AttachStderr": false,
            "Tty": false,
            "OpenStdin": false,
            "StdinOnce": false,
            "Env": [
                "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
            ],
            "Cmd": [
                "/bin/sh",
                "-c",
                "#(nop) CMD [\\"/hello\\"]"
            ],
            "Image": "sha256:0f9bb7da10de694b2babd0c1a3b75582a0db3395625cae5ab0fe537ce1cd831e",
            "Volumes": null,
            "WorkingDir": "",
            "Entrypoint": null,
            "OnBuild": null,
            "Labels": {}
        },
        "DockerVersion": "1.10.3",
        "Author": "",
        "Config": {
            "Hostname": "c65bc554a4b7",
            "Domainname": "",
            "User": "",
            "AttachStdin": false,
            "AttachStdout": false,
            "AttachStderr": false,
            "Tty": false,
            "OpenStdin": false,
            "StdinOnce": false,
            "Env": [
                "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
            ],
            "Cmd": [
                "/hello"
            ],
            "Image": "sha256:0f9bb7da10de694b2babd0c1a3b75582a0db3395625cae5ab0fe537ce1cd831e",
            "Volumes": null,
            "WorkingDir": "",
            "Entrypoint": null,
            "OnBuild": null,
            "Labels": {}
        },
        "Architecture": "amd64",
        "Os": "linux",
        "Size": 1848,
        "VirtualSize": 1848,
        "GraphDriver": {
            "Name": "devicemapper",
            "Data": {
                "DeviceId": "3",
                "DeviceName": "docker-8:1-394772-54b3ee6cc6589c1cda18e5c460e347510522c963aad5927d9c82ad05d3ddad65",
                "DeviceSize": "10737418240"
            }
        }
    }
]

6、删除本地镜像

docker rm <IMAGE_ID>：删除image
注意：删除镜像时，必须要先删除所依赖它的容器，容器就是运行镜像时产生的。用docker ps -l列出最后运行的容器，docker ps -a列出所有的容器，然后删除docker rm <容器id>
[root@i-r2irzkkd ~]# docker ps -l
CONTAINER ID        IMAGE                   COMMAND             CREATED             STATUS                     PORTS               NAMES
023c9cb85f58        docker.io/hello-world   "/hello"            3 seconds ago       Exited (0) 2 seconds ago                       tiny_mccarthy
[root@i-r2irzkkd ~]# docker rm 023c9cb85f58
023c9cb85f58
[root@i-r2irzkkd ~]# docker rmi docker.io/hello-world
Untagged: docker.io/hello-world:latest
Deleted: sha256:c54a2cc56cbb2f04003c1cd4507e118af7c0d340fe7e2720f70976c4b75237dc
Deleted: sha256:a02596fdd012f22b03af6ad7d11fa590c57507558357b079c3e8cebceb4262d7
[root@i-r2irzkkd ~]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
docker.io/centos    latest              970633036444        5 weeks ago         196.7 MB

7、删除镜像常用命令

杀死所有正在运行的容器  
docker kill $(docker ps -a -q)  
删除所有已经停止的容器  
docker rm $(docker ps -a -q)  
删除所有未打 dangling 标签的镜像  
docker rmi $(docker images -q -f dangling=true)  
删除所有镜像  
docker rmi $(docker images -q)

[root@i-r2irzkkd ~]# docker ps -l
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                     PORTS               NAMES
92a03ad57200        docker.io/centos    "/bin/bash"         2 minutes ago       Exited (0) 2 minutes ago                       berserk_kalam
[root@i-r2irzkkd ~]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
docker.io/centos    latest              970633036444        5 weeks ago         196.7 MB
[root@i-r2irzkkd ~]# docker ps -a -q
92a03ad57200
[root@i-r2irzkkd ~]# docker kill $(docker ps -a -q) 
Failed to kill container (92a03ad57200): Error response from daemon: Cannot kill container 92a03ad57200: Container 92a03ad572005c45ec7181ecff7c0510e83cca0b6ec6944a2aaa1d51c1a7f143 is not running
[root@i-r2irzkkd ~]# docker rmi $(docker images -q)
Untagged: docker.io/centos:latest
Deleted: sha256:97063303644439d9cea259b0e5f4b468633c90d88bf526acc67e5ae0a6e9427c
Deleted: sha256:f59b7e59ceaafc8c2c7e340f5831b7e4cf36203e3aeb59317942b9dec9557ac5
[root@i-r2irzkkd ~]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE

8、创建镜像

从官方仓库中下载一个镜像，修改后，通过docker commit命令来生成一个新镜像。
从官方下载centOS的latest镜像,接近200M，下载有点慢

[root@i-r2irzkkd ~]# docker pull docker.io/centos
Using default tag: latest
Trying to pull repository docker.io/library/centos ... 
latest: Pulling from docker.io/library/centos
3d8673bd162a: Pull complete 
Digest: sha256:a66ffcb73930584413de83311ca11a4cb4938c9b2521d331026dad970c19adf4
Status: Downloaded newer image for docker.io/centos:latest
[root@i-r2irzkkd ~]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
docker.io/centos    latest              970633036444        5 weeks ago         196.7 MB

centos就是一个操作系统，我们运行这个镜像，并进入这个镜像产生的容器,在容器的/opt下创建一个文件夹soft，然后保存为一个新镜像，

[root@i-r2irzkkd ~]# docker run -i -t docker.io/centos /bin/bash

退出后再进入
[root@i-r2irzkkd ~]# docker exec -it 83bddfe23ae7 /bin/bash

[root@1a606cbec84e /]# ls
anaconda-post.log  bin  dev  etc  home  lib  lib64  lost+found  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var
[root@1a606cbec84e /]# cd /opt
[root@1a606cbec84e opt]# ls
[root@1a606cbec84e opt]# mkdir soft
[root@1a606cbec84e opt]# exit
exit
[root@i-r2irzkkd ~]# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED              STATUS                     PORTS               NAMES
1a606cbec84e        docker.io/centos    "/bin/bash"         About a minute ago   Exited (0) 8 seconds ago                       pedantic_swirles

[root@i-r2irzkkd ~]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
docker.io/centos    latest              8ad522cbb1c1        6 seconds ago       196.7 MB
[root@i-r2irzkkd ~]# docker commit -m "test commit" -a "wolf" 1a606cbec84e docker.io/mycentos:0.0.1
sha256:ebfe84ea0343d85d733779518158bc09e5a0b37c79475f3df6d293d6c3c4e9fc
[root@i-r2irzkkd ~]# docker images
REPOSITORY           TAG                 IMAGE ID            CREATED             SIZE
docker.io/mycentos   0.0.1               ebfe84ea0343        1 seconds ago       196.7 MB
docker.io/centos     latest              8ad522cbb1c1        40 seconds ago      196.7 MB

查看新创建镜像的信息
[root@i-r2irzkkd ~]# docker inspect docker.io/mycentos:0.0.1
[
    {
        "Id": "sha256:ebfe84ea0343d85d733779518158bc09e5a0b37c79475f3df6d293d6c3c4e9fc",
        "RepoTags": [
            "docker.io/mycentos:0.0.1"
        ],
        "RepoDigests": [],
        "Parent": "sha256:97063303644439d9cea259b0e5f4b468633c90d88bf526acc67e5ae0a6e9427c",
        "Comment": "test commit",
        "Created": "2016-09-05T03:00:43.326346315Z",
        "Container": "1a606cbec84e4415b28c135c51f9e85f7892e10d4a09d823c2c4f67a69202607",
        "ContainerConfig": {
            "Hostname": "1a606cbec84e",
            "Domainname": "",
            "User": "",
            "AttachStdin": true,
            "AttachStdout": true,
            "AttachStderr": true,
            "Tty": true,
            "OpenStdin": true,
            "StdinOnce": true,
            "Env": [
                "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
            ],
            "Cmd": [
                "/bin/bash"
            ],
            "Image": "docker.io/centos",
            "Volumes": null,
            "WorkingDir": "",
            "Entrypoint": null,
            "OnBuild": null,
            "Labels": {
                "build-date": "20160729",
                "license": "GPLv2",
                "name": "CentOS Base Image",
                "vendor": "CentOS"
            }
        },
        "DockerVersion": "1.10.3",
        "Author": "wolf",
        "Config": {
            "Hostname": "",
            "Domainname": "",
            "User": "",
            "AttachStdin": false,
            "AttachStdout": false,
            "AttachStderr": false,
            "Tty": false,
            "OpenStdin": false,
            "StdinOnce": false,
            "Env": [
                "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
            ],
            "Cmd": [
                "/bin/bash"
            ],
            "Image": "",
            "Volumes": null,
            "WorkingDir": "",
            "Entrypoint": null,
            "OnBuild": null,
            "Labels": {
                "build-date": "20160729",
                "license": "GPLv2",
                "name": "CentOS Base Image",
                "vendor": "CentOS"
            }
        },
        "Architecture": "amd64",
        "Os": "linux",
        "Size": 196734890,
        "VirtualSize": 196734890,
        "GraphDriver": {
            "Name": "devicemapper",
            "Data": {
                "DeviceId": "13",
                "DeviceName": "docker-8:1-394772-850654f6c1dbaaf5b6d375d11be835e0224242273911386e7d7b8288279e95bb",
                "DeviceSize": "10737418240"
            }
        }
    }
]

9、导入容器快照

docker export导出一个容器快照
[root@i-r2irzkkd ~]# docker ps -a

容器 Docker

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