Docker镜像文件是否等同于清单文件，其中包含指向Docker镜像内部的指针 - 也就是不同的图层 - 其中的融合是Docker Image
OR
码头工作者图像文件是一个单片图像，其中包含所有不同的图层，并不一定指向不同的子图层吗？
答案 0 :(得分：3)
Docker image本质上是一个JSON清单，其中包括SHA256内容校验和对文件系统层的引用。
图层是一组只读的文件系统更改，当与其他图层组合时会生成图像的文件系统。
可以在图像之间共享图层
RootFS的{{1}}属性列出了图片的图层
docker inspect <image>您可以从图像的→ docker inspect openjdk:8-jre-alpine
[
{
"Id": "sha256:d85b17c6762eb3455c7b7ff1930bdde8c911137fe8c7f3c0b5988c66149dc27b",
"RepoTags": [
"openjdk:8-jre-alpine"
],
"RepoDigests": [
"openjdk@sha256:48ac96e309a748f5778db26be7e45ca0e35931ef58e9b271fe36767a55411728"
],
"Parent": "",
"Comment": "",
"Created": "2016-12-27T18:38:49.797530681Z",
"Container": "de5e277bf3e5ac747933bbb8e703382b240fdcdaef9d927faa4e02c1f0cbc35e",
"ContainerConfig": {
"Hostname": "26ba10d264c2",
"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:/usr/lib/jvm/java-1.8-openjdk/jre/bin:/usr/lib/jvm/java-1.8-openjdk/bin",
"LANG=C.UTF-8",
"JAVA_HOME=/usr/lib/jvm/java-1.8-openjdk/jre",
"JAVA_VERSION=8u111",
"JAVA_ALPINE_VERSION=8.111.14-r0"
],
"Cmd": [
"/bin/sh",
"-c",
"set -x \t&& apk add --no-cache \t\topenjdk8-jre=\"$JAVA_ALPINE_VERSION\" \t&& [ \"$JAVA_HOME\" = \"$(docker-java-home)\" ]"
],
"ArgsEscaped": true,
"Image": "sha256:7bf1d56e53b8a99662fc8314d3860b68f30798646ca0265aeeaa1275f679d314",
"Volumes": null,
"WorkingDir": "",
"Entrypoint": null,
"OnBuild": [],
"Labels": {}
},
"DockerVersion": "1.12.3",
"Author": "",
"Config": {
"Hostname": "26ba10d264c2",
"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:/usr/lib/jvm/java-1.8-openjdk/jre/bin:/usr/lib/jvm/java-1.8-openjdk/bin",
"LANG=C.UTF-8",
"JAVA_HOME=/usr/lib/jvm/java-1.8-openjdk/jre",
"JAVA_VERSION=8u111",
"JAVA_ALPINE_VERSION=8.111.14-r0"
],
"Cmd": null,
"ArgsEscaped": true,
"Image": "sha256:7bf1d56e53b8a99662fc8314d3860b68f30798646ca0265aeeaa1275f679d314",
"Volumes": null,
"WorkingDir": "",
"Entrypoint": null,
"OnBuild": [],
"Labels": {}
},
"Architecture": "amd64",
"Os": "linux",
"Size": 107853459,
"VirtualSize": 107853459,
"GraphDriver": {
"Name": "overlay2",
"Data": {
"LowerDir": "/var/lib/docker/overlay2/fccc5a703d4022f0fb561a3d0bc6c75da8a99aa1b3291f6be92bf8908e8d5add/diff:/var/lib/docker/overlay2/96ba8cd8b7b44ef284070bd4b98d912fd0bd2b9d6a0d906e661db901408ef38e/diff",
"MergedDir": "/var/lib/docker/overlay2/890f1dbb6c802344c58a32e0ee6d2b49dea74418963ab10a0b649ddc50da6127/merged",
"UpperDir": "/var/lib/docker/overlay2/890f1dbb6c802344c58a32e0ee6d2b49dea74418963ab10a0b649ddc50da6127/diff",
"WorkDir": "/var/lib/docker/overlay2/890f1dbb6c802344c58a32e0ee6d2b49dea74418963ab10a0b649ddc50da6127/work"
}
},
"RootFS": {
"Type": "layers",
"Layers": [
"sha256:7cbcbac42c44c6c38559e5df3a494f44987333c8023a40fec48df2fce1fc146b",
"sha256:da07d9b32b0090fa42690c204d7b49925b5e65ea770893d02c01ab00d61ff920",
"sha256:6f7515f190962a84c9837ad7adb1e684d79fa0d798a57a99fbe090cc0f97f39c"
]
}
}
]
看到，Dockerfile中有三个命令修改了文件系统。所有其他命令都有助于与图像关联的元数据（使用docker history获取完整输出）
--no-trunc