docker - 如何在Docker镜像中查看文件(示例:Docker的 'hello-world'镜像)

Question

我是Docker的新手，并且正在对官方Docker docker inspect镜像进行hello-world的操作，以下是其摘录:

C:\> docker inspect hello-world
[
    {
        "Id": "sha256:2cb0d9787c4dd17ef9eb03e512923bc4db10add190d3f84af63b744e353a9b34",
        "RepoTags": [
            "hello-world:latest"
        ],
        "RepoDigests": [
            "hello-world@sha256:4b8ff392a12ed9ea17784bd3c9a8b1fa3299cac44aca35a85c90c5e3c7afacdc"
        ],
        "Parent": "",
        "Comment": "",
        "Created": "2018-07-11T00:32:08.432822465Z",
        "Container": "6b6326f6afc81f7850b74670aad2bf550c7f2f07cd63282160e5eb564876087f",
        "ContainerConfig": {
            "Hostname": "6b6326f6afc8",
            "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\"]"
            ],
            "ArgsEscaped": true,
            "Image": "sha256:6bc48d210ad4c6bbb74e02e6196a9133b57107033c09e92cac12616cad30ebcf",
            "Volumes": null,
            "WorkingDir": "",
            "Entrypoint": null,
            "OnBuild": null,
            "Labels": {}
        },
        "DockerVersion": "17.06.2-ce",
        "Author": "",
        "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": [
                "/hello"
            ],
            "ArgsEscaped": true,
            "Image": "sha256:6bc48d210ad4c6bbb74e02e6196a9133b57107033c09e92cac12616cad30ebcf",
            "Volumes": null,
            "WorkingDir": "",
            "Entrypoint": null,
            "OnBuild": null,
            "Labels": null
        },
        "Architecture": "amd64",
        "Os": "linux",
        "Size": 1848,
        "VirtualSize": 1848,
        "GraphDriver": {
            "Data": {
                "MergedDir": "/var/lib/docker/overlay2/20d0631d9382f954d57631716e227ddbd42a0b383ae5e26241d5cf9fc92cbfe2/merged",
                "UpperDir": "/var/lib/docker/overlay2/20d0631d9382f954d57631716e227ddbd42a0b383ae5e26241d5cf9fc92cbfe2/diff",
                "WorkDir": "/var/lib/docker/overlay2/20d0631d9382f954d57631716e227ddbd42a0b383ae5e26241d5cf9fc92cbfe2/work"
            },
            "Name": "overlay2"
        },
        "RootFS": {
            "Type": "layers",
            "Layers": [
                "sha256:ee83fc5847cb872324b8a1f5dbfd754255367f4280122b4e2d5aee17818e31f5"
            ]
        },
        "Metadata": {
            "LastTagTime": "0001-01-01T00:00:00Z"
        }
    }
]

问题:

我以为需要定义一个Entrypoint来使容器可执行(这样，当我执行docker run hello-world时，您会看到通常看到的文本 Blob )，但是在下面的输出中，我看到Entrypoint是null。有任何想法吗？

我可以想象，如果我以交互方式运行容器，则可以深入文件系统以查看文件，但是hello-world图像在交互模式下不起作用。

Answer 1

在Docker中运行可执行文件有两种方法

CMD

ENTRYPOINT

每个可运行的docker镜像都需要CMD或ENTRYPOINT。
它们在容器根命令的形式上略有不同。
见 this question的差异
否则，出于所有实际目的，它们是相同的

从hello-world图片中可以看到，它的 CMD指定为 /hello