使用 docker 创建自己的镜像

时间:2022-08-11 16:49:58

docker run 命令

使用 docker 创建自己的镜像
镜像(image):An image is a filesystem and parameters to use at runtime. It doesn’t have state and never changes
容器(container): A container is a running instance of an image.
简言之,容器是镜像的实例。

运行命令的时候,执行如下步骤:
1 检查是否有名叫 hello-world 软件镜像(image)
2 如果没有,则从 docker hub 上下载
3 加载该镜像(image)到 容器(container)中,并运行

创建自己的镜像 image

首先运行 docker run docker/whalesay cowsay boo-boo
下载运行 docker hub 上的 whalesay 镜像。

- 创建一个 Dockerfile 文件

添加如下命令到文件中:
FROM docker/whalesay:latest (告诉docker当前的image是依靠于哪个image生成的)
RUN apt-get -y update && apt-get install -y fortunes(whalesay 镜像是基于ubuntu的,使用apt-get install来安装packages. 这两个命令更新了packages包,并安装了fortune 程序)
CMD /usr/games/fortune -a | cowsay(告诉镜像image在环境设置好以后的最后一个命令,该命令运行了furtune -a,并将输出发给额cowsay命令)
到这里,一个基本的Dockerfile就创建好了

- 根据 Dockerfile 来 Build 镜像

使用 docker build 命令来来创建镜像
-t 参数,给创建的镜像命名(give a tag)
. 不要忘记这个命令(就是一个英文句号),告诉 docker build 查找当前目录里的 dockerfile 文件。
$ docker build -t docker-whale .
 
Sending build context to Docker daemon 2.048 kB
...snip...
Removing intermediate container cb53c9d09f3b
Successfully built c2c3152907b5

  1. Docker检查确认所有build所需都齐了,输出如下消息:

    Sending build context to Docker daemon 2.048 kB
  2. Docker 检查 whalesay image 是否存在,不存在则从Docker Hub上pull下来。

    Step 1 : FROM docker/whalesay:latest
    ---> 6b362a9f73eb

    在每一步结束,都会有一个ID被打印出来。这个ID是每一步创建出的 Layer 的ID。 Dockerfile 中每一行命令都和 image 中的一个 Layer 相关。你自己的ID会显示的不一样。

  3. Docker 创建一个临时容器 container 来运行 whalesay 镜像image。在这个临时容器中,Docker 运行 Dockerfile中的下一条命令, 即 RUN 命令。这会安装 fortune 。这里会有很多输出,就和在 Ubuntu 中创建出来的消息一样。

    Step 2 : RUN apt-get -y update && apt-get install -y fortunes
    ---> Running in 05d4eda04526
    Ign http://archive.ubuntu.com trusty InRelease
    Get:1 http://archive.ubuntu.com trusty-updates InRelease [65.9 kB]
    Get:2 http://archive.ubuntu.com trusty-security InRelease [65.9 kB]
    Hit http://archive.ubuntu.com trusty Release.gpg
    Hit http://archive.ubuntu.com trusty Release
    Get:3 http://archive.ubuntu.com trusty-updates/main Sources [480 kB]
    Get:4 http://archive.ubuntu.com trusty-updates/restricted Sources [5921 B]
    Get:5 http://archive.ubuntu.com trusty-updates/universe Sources [214 kB]
    Get:6 http://archive.ubuntu.com trusty-updates/main amd64 Packages [1160 kB]
    Get:7 http://archive.ubuntu.com trusty-updates/restricted amd64 Packages [20.4 kB]
    Get:8 http://archive.ubuntu.com trusty-updates/universe amd64 Packages [505 kB]
    Get:9 http://archive.ubuntu.com trusty-security/main Sources [157 kB]
    Get:10 http://archive.ubuntu.com trusty-security/restricted Sources [4621 B]
    Get:11 http://archive.ubuntu.com trusty-security/universe Sources [54.5 kB]
    Get:12 http://archive.ubuntu.com trusty-security/main amd64 Packages [700 kB]
    Get:13 http://archive.ubuntu.com trusty-security/restricted amd64 Packages [17.0 kB]
    Get:14 http://archive.ubuntu.com trusty-security/universe amd64 Packages [191 kB]
    Hit http://archive.ubuntu.com trusty/main Sources
    Hit http://archive.ubuntu.com trusty/restricted Sources
    Hit http://archive.ubuntu.com trusty/universe Sources
    Hit http://archive.ubuntu.com trusty/main amd64 Packages
    Hit http://archive.ubuntu.com trusty/restricted amd64 Packages
    Hit http://archive.ubuntu.com trusty/universe amd64 Packages
    Fetched 3640 kB in 11s (329 kB/s)
    Reading package lists...
    Reading package lists...
    Building dependency tree...
    Reading state information...
    The following extra packages will be installed:
    fortune-mod fortunes-min librecode0
    Suggested packages:
    x11-utils bsdmainutils
    The following NEW packages will be installed:
    fortune-mod fortunes fortunes-min librecode0
    0 upgraded, 4 newly installed, 0 to remove and 92 not upgraded.
    Need to get 1961 kB of archives.
    After this operation, 4817 kB of additional disk space will be used.
    Get:1 http://archive.ubuntu.com/ubuntu/ trusty/main librecode0 amd64 3.6-21 [771 kB]
    Get:2 http://archive.ubuntu.com/ubuntu/ trusty/universe fortune-mod amd64 1:1.99.1-7 [39.5 kB]
    Get:3 http://archive.ubuntu.com/ubuntu/ trusty/universe fortunes-min all 1:1.99.1-7 [61.8 kB]
    Get:4 http://archive.ubuntu.com/ubuntu/ trusty/universe fortunes all 1:1.99.1-7 [1089 kB]
    debconf: unable to initialize frontend: Dialog
    debconf: (TERM is not set, so the dialog frontend is not usable.)
    debconf: falling back to frontend: Readline
    debconf: unable to initialize frontend: Readline
    debconf: (This frontend requires a controlling tty.)
    debconf: falling back to frontend: Teletype
    dpkg-preconfigure: unable to re-open stdin:
    Fetched 1961 kB in 19s (101 kB/s)
    Selecting previously unselected package librecode0:amd64.
    (Reading database ... 13116 files and directories currently installed.)
    Preparing to unpack .../librecode0_3.6-21_amd64.deb ...
    Unpacking librecode0:amd64 (3.6-21) ...
    Selecting previously unselected package fortune-mod.
    Preparing to unpack .../fortune-mod_1%3a1.99.1-7_amd64.deb ...
    Unpacking fortune-mod (1:1.99.1-7) ...
    Selecting previously unselected package fortunes-min.
    Preparing to unpack .../fortunes-min_1%3a1.99.1-7_all.deb ...
    Unpacking fortunes-min (1:1.99.1-7) ...
    Selecting previously unselected package fortunes.
    Preparing to unpack .../fortunes_1%3a1.99.1-7_all.deb ...
    Unpacking fortunes (1:1.99.1-7) ...
    Setting up librecode0:amd64 (3.6-21) ...
    Setting up fortune-mod (1:1.99.1-7) ...
    Setting up fortunes-min (1:1.99.1-7) ...
    Setting up fortunes (1:1.99.1-7) ...
    Processing triggers for libc-bin (2.19-0ubuntu6.6) ...
    ---> dfaf993d4a2e
    Removing intermediate container 05d4eda04526

    RUN 结束,有一个 layer 会被创建,并且之前创建的临时容器 container 也被去除了。

  4. 一个新的临时容器 container 被创建出来,Docker 为CMD命令添加一个 Layer,然后在移除该容器 congtainer

    Step 3 : CMD /usr/games/fortune -a | cowsay
    ---> Running in a8e6faa88df3
    ---> 7d9495d03763
    Removing intermediate container a8e6faa88df3
    Successfully built 7d9495d03763

到这里,我们就创建了一个自己的镜像 image,名叫 docker-whale.

接下来直接运行 docker run docker-whale