exec: "sleep 86400": executable file not found in $PATH

首先使用 imagebuilder、Dockerfile.min 以及文档中记录的 docker run、docker inspect 和 docker run ... sleep 1 命令复现该行为。跟踪生成的 Cmd 和 Entrypoint 值的来源，并将它们与基础镜像的元数据进行比较。当意外命令和启动失败的原因已确定，并由回归测试覆盖时，即表示完成。

I must be doing something wrong here but can't figure out what.

With imagebuilder from latest head, and docker-1.13.1-51.git4032bd5.fc27.x86_64

$ imagebuilder -t foo -f Dockerfile.min .
--> FROM fedora:27 as 0
--> RUN touch /etc/foo
--> Committing changes to foo ...
--> Done
$ docker run -it --rm foo 
/usr/bin/docker-current: Error response from daemon: oci runtime error: container_linux.go:247: starting container process caused "exec: \"sleep 86400\": executable file not found in $PATH".
$ docker run -it --rm foo /bin/bash
[root@7e2cdeabd622 /]# exit
$ docker run -it --rm foo sleep 1
$

First of all, where did "sleep 86400" come from? fedora:27 has no Cmd or Entrypoint set. foo does.

$ docker run -it --rm fedora:27
/usr/bin/docker-current: Error response from daemon: No command specified.
See '/usr/bin/docker-current run --help'.
$ docker inspect foo
[
    {
        "Id": "sha256:948b2333e11c0dfbedf4bde7e7a7fe6749376dd5d5fae112992edfa600838ad8",
        "RepoTags": [
            "foo:latest"
        ],
        "RepoDigests": [],
        "Parent": "sha256:9110ae7f579f35ee0c3938696f23fe0f5fbe641738ea52eb83c2df7e9995fa17",
        "Comment": "",
        "Created": "2018-04-18T19:01:37.421678496Z",
        "Container": "fc1eb310d84b08683a2eab434268e46313bdf46b2a533606e4cdbed1a5e7727e",
        "ContainerConfig": {
            "Hostname": "fc1eb310d84b",
            "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",
                "DISTTAG=f27container",
                "FGC=f27",
                "FBR=f27"
            ],
            "Cmd": [
                "sleep 86400"
            ],
            "Image": "fedora:27",
            "Volumes": null,
            "WorkingDir": "",
            "Entrypoint": [
                "/bin/sh",
                "-c"
            ],
            "OnBuild": null,
            "Labels": {}
        },
        "DockerVersion": "1.13.1",
        "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",
                "DISTTAG=f27container",
                "FGC=f27",
                "FBR=f27"
            ],
            "Cmd": [
                "sleep 86400"
            ],
            "Image": "",
            "Volumes": null,
            "WorkingDir": "",
            "Entrypoint": [],
            "OnBuild": null,
            "Labels": {}
        },
        "Architecture": "amd64",
        "Os": "linux",
        "Size": 235250693,
        "VirtualSize": 235250693,
        "GraphDriver": {
            "Name": "overlay2",
            "Data": {
                "LowerDir": "/var/lib/docker/overlay2/70bea816b920919e3afcdaca1f7c572c83308f4bee6379450e17acba57da28ff/diff",
                "MergedDir": "/var/lib/docker/overlay2/6e1b01b002e68b2410fe67bcfee1bc7647346563074c82bc1abc534681459b01/merged",
                "UpperDir": "/var/lib/docker/overlay2/6e1b01b002e68b2410fe67bcfee1bc7647346563074c82bc1abc534681459b01/diff",
                "WorkDir": "/var/lib/docker/overlay2/6e1b01b002e68b2410fe67bcfee1bc7647346563074c82bc1abc534681459b01/work"
            }
        },
        "RootFS": {
            "Type": "layers",
            "Layers": [
                "sha256:39bae602f7539e626f6894ecded6d12a6c56745dbab9aee940e258c766e090e8",
                "sha256:de41557ebc416b99c4bb90ae5e39f4c451055236db8aff0cbe10f8206a275039"
            ]
        }
    }
]

Second, why does it fail to run that?