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第六章 Docker---镜像的命令详解

第六章 Docker---镜像的命令详解

作者: 箫起秦楼 | 来源:发表于2018-11-26 20:06 被阅读0次

    1. 下载与查看镜像:

    [root@centos_7_1]:[~]# docker search alpine
    NAME                                   DESCRIPTION                                     STARS               OFFICIAL            AUTOMATED
    alpine                                 A minimal Docker image based on Alpine Linux…   4598                [OK]
    mhart/alpine-node                      Minimal Node.js built on Alpine Linux           401
    anapsix/alpine-java                    Oracle Java 8 (and 7) with GLIBC 2.28 over A…   368                  [OK]
    
    #-----------------------------分割线,篇幅有限,中间已省略-----------------------------
    spotify/alpine                         Alpine image with `bash` and `curl`.            5                  [OK]
    functions/alpine                       Alpine Linux / BusyBox with the OpenFaaS wat…   4
    govuk/gemstash-alpine                  Gemstash server running on Alpine               3                  [OK]
    smartentry/alpine                      alpine with smartentry                          0
    #-----------------------------分割线-----------------------------
    [root@centos_7_1]:[~]# docker image ls
    REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
    #-----------------------------分割线-----------------------------
    [root@centos_7_1]:[~]# docker image pull alpine:3.8
    3.8: Pulling from library/alpine
    4fe2ade4980c: Pull complete
    Digest: sha256:621c2f39f8133acb8e64023a94dbdf0d5ca81896102b9e57c0dc184cadaf5528
    Status: Downloaded newer image for alpine:3.8
    #-----------------------------分割线-----------------------------
    [root@centos_7_1]:[~]# docker image ls
    REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
    alpine              3.8                 196d12cf6ab1        2 months ago        4.41MB
    #-----------------------------分割线-----------------------------
    [root@centos_7_1]:[~]# docker image ls --no-trunc
    REPOSITORY          TAG                 IMAGE ID                                                                  CREATED       SIZE
    alpine              3.8                 sha256:196d12cf6ab19273823e700516e98eb1910b03b17840f9d5509f03858484d321   2 months ago       4.41MB
    

    上述命令详细说明:

    • docker search alpine
      • 查看互联网远程仓库中的apine所有镜像。
    • docker image ls
      • 列出本地主机镜像
      • Linux中的ls命令通用与Docker容器中
    • docker image pull alpine:3.8
      • 从互联网上的Registry仓库下载Docker镜像,必须确认,已设置Docker镜像加速,如阿里云的镜像加速。
      • alpine:3.8 镜像格式说明:镜像名:标签
    • 显示镜像时,显示各种属性的含义:
      • REPOSITORY 镜像所属仓库
      • TAG 镜像标签
      • IMAGE ID 镜像ID(每个镜像都有一个标识符)
      • CREATED 镜像创建时间
      • SIZE 镜像大小
    • docker image ls --no-trunc
      • 这里显示完整image ID,如不加--no-trunc,则默认显示简写ID。
    • docker image ls --digests
      • 查看 image(镜像)的完整的哈希值:

    2. 镜像文件的标签TAG

    • 镜像文件可以不加标签,默认是最新版本,如:
    [root@centos_7_1]:[~]# docker image pull alpine
    Using default tag: latest   # 不加标签的情况下,默认标签为:latest
    latest: Pulling from library/alpine
    Digest: sha256:621c2f39f8133acb8e64023a94dbdf0d5ca81896102b9e57c0dc184cadaf5528
    Status: Downloaded newer image for alpine:latest
    #-----------------------------分割线-----------------------------
    [root@centos_7_1]:[~]# docker image ls
    REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
    alpine              3.8                 196d12cf6ab1        2 months ago        4.41MB
    alpine              latest              196d12cf6ab1        2 months ago        4.41MB
    
    • 在上述案例中,可以看到镜像的ID(IMAGE ID);
    • 表示这两个镜像文件其实是一个文件;
    • 只是用两个标签显示,而且下载第二个文件时速度特别快;
    • 这代表系统命令执行时,会扫码本地镜像文件,与互联网文件作对比,如果本地存在,只是做加标签处理。
    • 如果下载镜像时不注明标签,则默认下载最新版。
    • 最新版默认标签为:latest。

    3. 删除镜像:

    [root@centos_7_1]:[~]# docker image rm alpine:3.8
    Untagged: alpine:3.8
    [root@centos_7_1]:[~]# docker image ls
    REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
    alpine              latest              196d12cf6ab1        2 months ago        4.41MB
    #-----------------------------分割线-----------------------------
    [root@centos_7_1]:[~]# docker image rm alpine:latest
    Untagged: alpine:latest
    Untagged: alpine@sha256:621c2f39f8133acb8e64023a94dbdf0d5ca81896102b9e57c0dc184cadaf5528
    Deleted: sha256:196d12cf6ab19273823e700516e98eb1910b03b17840f9d5509f03858484d321
    Deleted: sha256:df64d3292fd6194b7865d7326af5255db6d81e9df29f48adde61a918fbd8c332
    [root@centos_7_1]:[~]# docker image ls
    REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
    
    • 删除镜像时,加标签,则删除相应标签的镜像文件;
    • 如果不加标签,默认删除标签为latest的镜像文件;
    • 如果一个镜像文件有多个标签;
    • 则删除最后一个标签时,才是真正删除了镜像文件,以前的删除只是删除了标签而已。

    4. 镜像的详细信息(元数据)

    [root@centos_7_1]:[~]# docker image pull alpine:3.8
    3.8: Pulling from library/alpine
    4fe2ade4980c: Already exists
    Digest: sha256:621c2f39f8133acb8e64023a94dbdf0d5ca81896102b9e57c0dc184cadaf5528
    Status: Downloaded newer image for alpine:3.8
    #-----------------------------分割线-----------------------------
    [root@centos_7_1]:[~]#  docker image inspect alpine:3.8
    [
        {
            "Id": "sha256:196d12cf6ab19273823e700516e98eb1910b03b17840f9d5509f03858484d321",
            "RepoTags": [
                "alpine:3.8"
            ],
            "RepoDigests": [
                "alpine@sha256:621c2f39f8133acb8e64023a94dbdf0d5ca81896102b9e57c0dc184cadaf5528"
            ],
    #-----------------------------分割线,篇幅有限,中间已省略-----------------------------
    

    上述命令详细说明

    • docker image pull alpine:3.8
      • inspect命令:显示镜像的详细信息(镜像的元数据)。
    • 这里需要特别说明中间的一段代码:
    "Cmd": [
                    "/bin/sh",
                    "-c",
                    "#(nop) ",
                    "CMD [\"/bin/sh\"]"
                ],
    
    
    • 这段代码表示:以这个镜像创建的容器,容器启动时默认启动的应用进程为/bin/sh。

    5. Docker镜像命令的所有子命令

    #-----------------------------分割线-----------------------------
    [root@centos_7_1]:[~]# docker image ls --digests
    REPOSITORY          TAG                 DIGEST                                                                    IMAGE ID       CREATED             SIZE
    alpine              3.8                 sha256:621c2f39f8133acb8e64023a94dbdf0d5ca81896102b9e57c0dc184cadaf5528   196d12cf6ab1       2 months ago        4.41MB
    #-----------------------------分割线-----------------------------
    [root@centos_7_1]:[~]# docker image ls --help
    
    Usage:  docker image ls [OPTIONS] [REPOSITORY[:TAG]]
    
    List images
    
    Aliases:
      ls, images, list
    
    Options:
      -a, --all             Show all images (default hides intermediate images)
          --digests         Show digests
      -f, --filter filter   Filter output based on conditions provided
          --format string   Pretty-print images using a Go template
          --no-trunc        Don't truncate output
      -q, --quiet           Only show numeric IDs
    #-----------------------------分割线-----------------------------
    [root@centos_7_1]:[~]# docker image --help
    
    Usage:  docker image COMMAND
    
    Manage images
    
    Commands:
      build       Build an image from a Dockerfile
      history     Show the history of an image
      import      Import the contents from a tarball to create a filesystem image
      inspect     Display detailed information on one or more images
      load        Load an image from a tar archive or STDIN
      ls          List images
      prune       Remove unused images
      pull        Pull an image or a repository from a registry
      push        Push an image or a repository to a registry
      rm          Remove one or more images
      save        Save one or more images to a tar archive (streamed to STDOUT by default)
      tag         Create a tag TARGET_IMAGE that refers to SOURCE_IMAGE
    
    Run 'docker image COMMAND --help' for more information on a command.
    
    • docker image ls --help
      • 查看关于docker镜像命令中子命令ls的详细使用方法
    • docker image --help
      • 显示所有Docker镜像的所有子命令

    6. Docker新版本与老版本命令对比

    [root@centos_7_1]:[~]# docker image ls
    REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
    alpine              3.8                 196d12cf6ab1        2 months ago        4.41MB
    [root@centos_7_1]:[~]# docker images
    REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
    alpine              3.8                 196d12cf6ab1        2 months ago        4.41MB
    
    • Docker镜像命令:
      • 老版本:
        • docker images
      • 新版本:
        • docker images
          Docker分类---文章目录:

    第一章 初识Docker | 点击此处
    第二章 安装Docker以及简单配置 | 点击此处
    第三章 Docker容器的生命周期 | 点击此处
    第四章 Docker命令汇总 | 点击此处
    第五章 Docker基础命令详解 | 点击此处
    第六章 Docker---镜像的命令详解 | 点击此处
    第七章 Docker---容器的命令详解 | 点击此处
    第八章 Docker与Alpine不解之缘 | 点击此处
    未完待续

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