entityMap|blocks|key|4lvkv|text|这在这一点上是不可能的(除非镜像的作者显式地包含了Dockerfile)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|454po|然而，它绝对是有用的东西！有两件事将有助于获得此功能。|2scha|受信任的构建(详细信息请参阅|c6d7n|此docker-dev讨论|e05si|构建过程生成的连续图像中更详细的元数据。从长远来看，元数据应该指出哪个构建命令生成了图像，这意味着可以从图像序列重建Dockerfile。^0|0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|K|9|@]|A|@]|B|$]]|$2|C|4|D|6|7|8|L|9|@]|A|@]|B|$]]|$2|E|4|F|6|7|8|M|9|@]|A|@]|B|$]]|$2|G|4|H|6|7|8|N|9|@]|A|@]|B|$]]|$2|I|4|J|6|7|8|O|9|@]|A|@]|B|$]]]]

It is not possible at this point (unless the author of the image explicitly included the Dockerfile).

However, it is definitely something useful! There are two things that will help to obtain this feature.

<ol>
<li>Trusted builds (detailed in <a href="https://groups.google.com/forum/#!topic/docker-dev/NDigdAk9trc">this docker-dev discussion</a></li>
<li>More detailed metadata in the successive images produced by the build process. In the long run, the metadata should indicate which build command produced the image, which means that it will be possible to reconstruct the Dockerfile from a sequence of images.</li>
</ol>

entityMap|blocks|key|jgq|text|若要了解docker映像是如何构建的，请使用|type|unstyled|depth|inlineStyleRanges|entityRanges|data|cqaan|命令。|75b21|您可以从映像构建docker文件，但它不会包含您希望完全了解映像是如何生成的所有内容。您可以合理地提取dockerfile的MAINTAINER、ENV、EXPOSE、VOLUME、WORKDIR、ENTRYPOINT、CMD和ONBUILD部分。|c6j2n|以下脚本应该适用于您：|4hni1|#!/bin/bash
docker+history+--no-trunc+"$1"+%7C+\
sed+-n+-e+'s,.*/bin/sh+-c+#(nop)+$MAINTAINER+.*[%5E+]$+*0+B,\1,p'+%7C+\
head+-1
docker+inspect+--format='{{range+$e+:=+.Config.Env}}
ENV+{{$e}}
{{end}}{{range+$e,$v+:=+.Config.ExposedPorts}}
EXPOSE+{{$e}}
{{end}}{{range+$e,$v+:=+.Config.Volumes}}
VOLUME+{{$e}}
{{end}}{{with+.Config.User}}USER+{{.}}{{end}}
{{with+.Config.WorkingDir}}WORKDIR+{{.}}{{end}}
{{with+.Config.Entrypoint}}ENTRYPOINT+{{json+.}}{{end}}
{{with+.Config.Cmd}}CMD+{{json+.}}{{end}}
{{with+.Config.OnBuild}}ONBUILD+{{json+.}}{{end}}'+"$1"|code-block|syntax|javascript|3cm63|我使用它作为脚本的一部分，将正在运行的容器重新构建为镜像：|8jab7|https://github.com/docbill/docker-scripts/blob/master/docker-rebase|a10hs|Dockerfile主要用于需要重新打包镜像的情况。|f1jmp|需要记住的是，docker镜像实际上可以是真实或虚拟机的tar备份。我已经用这种方式制作了几个docker图像。甚至构建历史都显示我导入了一个巨大的tar文件作为创建镜像的第一步……^0|0|0|0|0|0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|V|9|@]|A|@]|B|$]]|$2|C|4|D|6|7|8|W|9|@]|A|@]|B|$]]|$2|E|4|F|6|7|8|X|9|@]|A|@]|B|$]]|$2|G|4|H|6|7|8|Y|9|@]|A|@]|B|$]]|$2|I|4|J|6|K|8|Z|9|@]|A|@]|B|$L|M]]|$2|N|4|O|6|7|8|10|9|@]|A|@]|B|$]]|$2|P|4|Q|6|7|8|11|9|@]|A|@]|B|$]]|$2|R|4|S|6|7|8|12|9|@]|A|@]|B|$]]|$2|T|4|U|6|7|8|13|9|@]|A|@]|B|$]]]]

To understand how a docker image was built, use the
<code>docker history --no-trunc</code> command.

You can build a docker file from an image, but it will not contain everything you would want to fully understand how the image was generated. Reasonably what you can extract is the MAINTAINER, ENV, EXPOSE, VOLUME, WORKDIR, ENTRYPOINT, CMD, and ONBUILD parts of the dockerfile.

The following script should work for you:

<pre><code>#!/bin/bash
docker history --no-trunc "$1" | \
sed -n -e 's,.*/bin/sh -c #(nop) $MAINTAINER .*[^ ]$ *0 B,\1,p' | \
head -1
docker inspect --format='{{range $e := .Config.Env}}
ENV {{$e}}
{{end}}{{range $e,$v := .Config.ExposedPorts}}
EXPOSE {{$e}}
{{end}}{{range $e,$v := .Config.Volumes}}
VOLUME {{$e}}
{{end}}{{with .Config.User}}USER {{.}}{{end}}
{{with .Config.WorkingDir}}WORKDIR {{.}}{{end}}
{{with .Config.Entrypoint}}ENTRYPOINT {{json .}}{{end}}
{{with .Config.Cmd}}CMD {{json .}}{{end}}
{{with .Config.OnBuild}}ONBUILD {{json .}}{{end}}' "$1"
</code></pre>

I use this as part of a script to rebuild running containers as images: 
<a href="https://github.com/docbill/docker-scripts/blob/master/docker-rebase" rel="noreferrer">https://github.com/docbill/docker-scripts/blob/master/docker-rebase</a>

The Dockerfile is mainly useful if you want to be able to repackage an image.

The thing to keep in mind, is a docker image can actually just be the tar backup of a real or virtual machine. I have made several docker images this way. Even the build history shows me importing a huge tar file as the first step in creating the image...

entityMap|blocks|key|3jvm8|text|不知何故，我完全错过了被接受的答案中的实际命令，所以这里又一次，在它自己的段落中更明显地看到，有多少人像我一样|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2dtpn|$+docker+history+--no-trunc|code-block|syntax|javascript^0|0^^$0|$]|1|@$2|3|4|5|6|7|8|H|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|I|9|@]|A|@]|B|$F|G]]]]

I somehow absolutely missed the actual command in the accepted answer, so here it is again, bit more visible in its own paragraph, to see how many people are like me

<pre><code>$ docker history --no-trunc &lt;IMAGE_ID&gt;
</code></pre>

entityMap|blocks|key|d4pp1|text|bash解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5ukg4|docker+history+--no-trunc+$argv++%7C+tac+%7C+tr+-s+'+'+%7C+cut+-d+"+"+-f+5-+%7C+sed+'s,%5E/bin/sh+-c+#(nop)+,,g'+%7C+sed+'s,%5E/bin/sh+-c,RUN,g'+%7C+sed+'s,+&&+,\n++&+,g'+%7C+sed+'s,\s*[0-9]*[\.]*[0-9]*\s*[kMG]*B\s*$,,g'+%7C+head+-n+-1|code-block|syntax|javascript|4aiv7|分步解释：|91c2k|tac+:+reverse+the+file
tr+-s+'+'+++++++++++++++++++++++++++++++++++++++trim+multiple+whitespaces+into+1
cut+-d+"+"+-f+5-++++++++++++++++++++++++++++++++remove+the+first+fields+(until+X+months/years+ago)
sed+'s,%5E/bin/sh+-c+#(nop)+,,g'++++++++++++++++++remove+/bin/sh+calls+for+ENV,LABEL...
sed+'s,%5E/bin/sh+-c,RUN,g'+++++++++++++++++++++++remove+/bin/sh+calls+for+RUN
sed+'s,+&&+,\n++&+,g'+++++++++++++++++++++++++++pretty+print+multi+command+lines+following+Docker+best+practices
sed+'s,\s*[0-9]*[\.]*[0-9]*\s*[kMG]*B\s*$,,g'++++++remove+layer+size+information
head+-n+-1++++++++++++++++++++++++++++++++++++++remove+last+line+("SIZE+COMMENT"+in+this+case)|5bdc7|示例：|f4g0q|~++dih+ubuntu:18.04
ADD+file:28c0771e44ff530dba3f237024acc38e8ec9293d60f0e44c8c78536c12f13a0b+in+/
RUN+set+-xe
+++&&++echo+'#!/bin/sh'+>+/usr/sbin/policy-rc.d
+++&&++echo+'exit+101'+>>+/usr/sbin/policy-rc.d
+++&&++chmod+%2Bx+/usr/sbin/policy-rc.d
+++&&++dpkg-divert+--local+--rename+--add+/sbin/initctl
+++&&++cp+-a+/usr/sbin/policy-rc.d+/sbin/initctl
+++&&++sed+-i+'s/%5Eexit.*/exit+0/'+/sbin/initctl
+++&&++echo+'force-unsafe-io'+>+/etc/dpkg/dpkg.cfg.d/docker-apt-speedup
+++&&++echo+'DPkg::Post-Invoke+{+"rm+-f+/var/cache/apt/archives/*.deb+/var/cache/apt/archives/partial/*.deb+/var/cache/apt/*.bin+%7C%7C+true";+};'+>+/etc/apt/apt.conf.d/docker-clean
+++&&++echo+'APT::Update::Post-Invoke+{+"rm+-f+/var/cache/apt/archives/*.deb+/var/cache/apt/archives/partial/*.deb+/var/cache/apt/*.bin+%7C%7C+true";+};'+>>+/etc/apt/apt.conf.d/docker-clean
+++&&++echo+'Dir::Cache::pkgcache+"";+Dir::Cache::srcpkgcache+"";'+>>+/etc/apt/apt.conf.d/docker-clean
+++&&++echo+'Acquire::Languages+"none";'+>+/etc/apt/apt.conf.d/docker-no-languages
+++&&++echo+'Acquire::GzipIndexes+"true";+Acquire::CompressionTypes::Order::+"gz";'+>+/etc/apt/apt.conf.d/docker-gzip-indexes
+++&&++echo+'Apt::AutoRemove::SuggestsImportant+"false";'+>+/etc/apt/apt.conf.d/docker-autoremove-suggests
RUN+rm+-rf+/var/lib/apt/lists/*
RUN+sed+-i+'s/%5E#\s*$deb.*universe$$/\1/g'+/etc/apt/sources.list
RUN+mkdir+-p+/run/systemd
+++&&++echo+'docker'+>+/run/systemd/container
CMD+["/bin/bash"]^0|0|0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|P|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|Q|9|@]|A|@]|B|$F|G]]|$2|H|4|I|6|7|8|R|9|@]|A|@]|B|$]]|$2|J|4|K|6|E|8|S|9|@]|A|@]|B|$F|G]]|$2|L|4|M|6|7|8|T|9|@]|A|@]|B|$]]|$2|N|4|O|6|E|8|U|9|@]|A|@]|B|$F|G]]]]

A bash solution :

<pre><code>docker history --no-trunc $argv | tac | tr -s ' ' | cut -d " " -f 5- | sed 's,^/bin/sh -c #(nop) ,,g' | sed 's,^/bin/sh -c,RUN,g' | sed 's, &amp;&amp; ,\n &amp; ,g' | sed 's,\s*[0-9]*[\.]*[0-9]*\s*[kMG]*B\s*$,,g' | head -n -1
</code></pre>

Step by step explanations:

<pre><code>tac : reverse the file
tr -s ' ' trim multiple whitespaces into 1
cut -d " " -f 5- remove the first fields (until X months/years ago)
sed 's,^/bin/sh -c #(nop) ,,g' remove /bin/sh calls for ENV,LABEL...
sed 's,^/bin/sh -c,RUN,g' remove /bin/sh calls for RUN
sed 's, &amp;&amp; ,\n &amp; ,g' pretty print multi command lines following Docker best practices
sed 's,\s*[0-9]*[\.]*[0-9]*\s*[kMG]*B\s*$,,g' remove layer size information
head -n -1 remove last line ("SIZE COMMENT" in this case)
</code></pre>

Example:

<pre><code> ~  dih ubuntu:18.04
ADD file:28c0771e44ff530dba3f237024acc38e8ec9293d60f0e44c8c78536c12f13a0b in /
RUN set -xe
 &amp;&amp; echo '#!/bin/sh' &gt; /usr/sbin/policy-rc.d
 &amp;&amp; echo 'exit 101' &gt;&gt; /usr/sbin/policy-rc.d
 &amp;&amp; chmod +x /usr/sbin/policy-rc.d
 &amp;&amp; dpkg-divert --local --rename --add /sbin/initctl
 &amp;&amp; cp -a /usr/sbin/policy-rc.d /sbin/initctl
 &amp;&amp; sed -i 's/^exit.*/exit 0/' /sbin/initctl
 &amp;&amp; echo 'force-unsafe-io' &gt; /etc/dpkg/dpkg.cfg.d/docker-apt-speedup
 &amp;&amp; echo 'DPkg::Post-Invoke { "rm -f /var/cache/apt/archives/*.deb /var/cache/apt/archives/partial/*.deb /var/cache/apt/*.bin || true"; };' &gt; /etc/apt/apt.conf.d/docker-clean
 &amp;&amp; echo 'APT::Update::Post-Invoke { "rm -f /var/cache/apt/archives/*.deb /var/cache/apt/archives/partial/*.deb /var/cache/apt/*.bin || true"; };' &gt;&gt; /etc/apt/apt.conf.d/docker-clean
 &amp;&amp; echo 'Dir::Cache::pkgcache ""; Dir::Cache::srcpkgcache "";' &gt;&gt; /etc/apt/apt.conf.d/docker-clean
 &amp;&amp; echo 'Acquire::Languages "none";' &gt; /etc/apt/apt.conf.d/docker-no-languages
 &amp;&amp; echo 'Acquire::GzipIndexes "true"; Acquire::CompressionTypes::Order:: "gz";' &gt; /etc/apt/apt.conf.d/docker-gzip-indexes
 &amp;&amp; echo 'Apt::AutoRemove::SuggestsImportant "false";' &gt; /etc/apt/apt.conf.d/docker-autoremove-suggests
RUN rm -rf /var/lib/apt/lists/*
RUN sed -i 's/^#\s*$deb.*universe$$/\1/g' /etc/apt/sources.list
RUN mkdir -p /run/systemd
 &amp;&amp; echo 'docker' &gt; /run/systemd/container
CMD ["/bin/bash"]
</code></pre>

entityMap|blocks|key|6sfh3|text|这是从@fallino的答案派生而来的，通过使用输出格式选项对其进行了一些调整和简化|type|unstyled|depth|inlineStyleRanges|entityRanges|data|8d6gn|docker历史记录|285ps|..。因为macOS和Gnu/Linux有不同的命令行实用程序，所以Mac需要一个不同的版本。如果您只需要其中之一，则可以使用这些行。|1ttu9|#!/bin/bash
case+"$OSTYPE"+in
++++linux*)
++++++++docker+history+--no-trunc+--format+"{{.CreatedBy}}"+$1+%7C+#+extract+information+from+layers
++++++++tac++++++++++++++++++++++++++++++++++++++++++++++++++++%7C+#+reverse+the+file
++++++++sed+'s,%5E$%7C3.*$\?/bin/$ba$\?sh+-c,RUN,'+++++++++++++%7C+#+change+/bin/(ba)?sh+calls+to+RUN
++++++++sed+'s,%5ERUN+#(nop)+*,,'++++++++++++++++++++++++++++++++%7C+#+remove+RUN+#(nop)+calls+for+ENV,LABEL...
++++++++sed+'s,++*&&++*,+\\\n+\&\&+,g'+++++++++++++++++++++++++++#+pretty+print+multi+command+lines+following+Docker+best+practices
++++;;
++++darwin*)
++++++++docker+history+--no-trunc+--format+"{{.CreatedBy}}"+$1+%7C+#+extract+information+from+layers
++++++++tail+-r++++++++++++++++++++++++++++++++++++++++++++++++%7C+#+reverse+the+file
++++++++sed+-E+'s,%5E(\%7C3.*)?/bin/(ba)?sh+-c,RUN,'+++++++++++++++%7C+#+change+/bin/(ba)?sh+calls+to+RUN
++++++++sed+'s,%5ERUN+#(nop)+*,,'++++++++++++++++++++++++++++++++%7C+#+remove+RUN+#(nop)+calls+for+ENV,LABEL...
++++++++sed+$'s,++*&&++*,+\\\+\\\n+\&\&+,g'++++++++++++++++++++++#+pretty+print+multi+command+lines+following+Docker+best+practices
++++;;
++++*)
++++++++echo+"unknown+OSTYPE:+$OSTYPE"
++++;;
esac|code-block|syntax|javascript^0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|L|9|@]|A|@]|B|$]]|$2|C|4|D|6|7|8|M|9|@]|A|@]|B|$]]|$2|E|4|F|6|7|8|N|9|@]|A|@]|B|$]]|$2|G|4|H|6|I|8|O|9|@]|A|@]|B|$J|K]]]]

This is derived from @fallino's answer, with some adjustments and simplifications by using the output format option for <a href="https://docs.docker.com/engine/reference/commandline/image_history/" rel="noreferrer">docker history</a>. Since macOS and Gnu/Linux have different command-line utilities, a different version is necessary for Mac. If you only need one or the other, you can just use those lines.

<pre><code>#!/bin/bash
case "$OSTYPE" in
 linux*)
 docker history --no-trunc --format "{{.CreatedBy}}" $1 | # extract information from layers
 tac | # reverse the file
 sed 's,^$|3.*$\?/bin/$ba$\?sh -c,RUN,' | # change /bin/(ba)?sh calls to RUN
 sed 's,^RUN #(nop) *,,' | # remove RUN #(nop) calls for ENV,LABEL...
 sed 's, *&amp;&amp; *, \\\n \&amp;\&amp; ,g' # pretty print multi command lines following Docker best practices
 ;;
 darwin*)
 docker history --no-trunc --format "{{.CreatedBy}}" $1 | # extract information from layers
 tail -r | # reverse the file
 sed -E 's,^(\|3.*)?/bin/(ba)?sh -c,RUN,' | # change /bin/(ba)?sh calls to RUN
 sed 's,^RUN #(nop) *,,' | # remove RUN #(nop) calls for ENV,LABEL...
 sed $'s, *&amp;&amp; *, \\\ \\\n \&amp;\&amp; ,g' # pretty print multi command lines following Docker best practices
 ;;
 *)
 echo "unknown OSTYPE: $OSTYPE"
 ;;
esac
</code></pre>

entityMap|blocks|key|7ihfs|text|更新2018年12月宝马的答案|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3fufv|chenzj/dfimage+-正如hub.docker.com上所描述的那样，从其他镜像重新生成Dockerfile。因此，您可以按如下方式使用它：|fqa2e|docker+pull+chenzj/dfimage
alias+dfimage="docker+run+-v+/var/run/docker.sock:/var/run/docker.sock+--rm+chenzj/dfimage"
dfimage+IMAGE_ID+>+Dockerfile|code-block|syntax|javascript^0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|J|9|@]|A|@]|B|$]]|$2|C|4|D|6|7|8|K|9|@]|A|@]|B|$]]|$2|E|4|F|6|G|8|L|9|@]|A|@]|B|$H|I]]]]

Update Dec 2018 to BMW's answer
chenzj/dfimage - as described on hub.docker.com regenerates Dockerfile from other images. So you can use it as follows:
<pre><code>docker pull chenzj/dfimage
alias dfimage=&quot;docker run -v /var/run/docker.sock:/var/run/docker.sock --rm chenzj/dfimage&quot;
dfimage IMAGE_ID &gt; Dockerfile
</code></pre>

entityMap|blocks|key|6cog7|text|​|type|unstyled|depth|inlineStyleRanges|entityRanges|data|83o3v|docker+pull+chenzj/dfimage


alias+dfimage="docker+run+-v+/var/run/docker.sock:/var/run/docker.sock+--rm+chenzj/dfimage"

dfimage+image_id|code-block|syntax|javascript|2m12f|eorpq|下面是dfimage命令的输出：|crc7v|$+dfimage+0f1947a021ce

FROM+node:8
WORKDIR+/usr/src/app

COPY+file:e76d2e84545dedbe901b7b7b0c8d2c9733baa07cc821054efec48f623e29218c+in+./
RUN+/bin/sh+-c+npm+install
COPY+dir:a89a4894689a38cbf3895fdc0870878272bb9e09268149a87a6974a274b2184a+in+.

EXPOSE+8080
CMD+["npm"+"start"]^0|0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|M|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|N|9|@]|A|@]|B|$F|G]]|$2|H|4|5|6|7|8|O|9|@]|A|@]|B|$]]|$2|I|4|J|6|7|8|P|9|@]|A|@]|B|$]]|$2|K|4|L|6|E|8|Q|9|@]|A|@]|B|$F|G]]]]

<div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-html lang-html prettyprint-override"><code>docker pull chenzj/dfimage


alias dfimage="docker run -v /var/run/docker.sock:/var/run/docker.sock --rm chenzj/dfimage"

dfimage image_id</code></pre>
</div>
</div>

Below is ouput of dfimage command:
<pre><code>$ dfimage 0f1947a021ce

FROM node:8
WORKDIR /usr/src/app

COPY file:e76d2e84545dedbe901b7b7b0c8d2c9733baa07cc821054efec48f623e29218c in ./
RUN /bin/sh -c npm install
COPY dir:a89a4894689a38cbf3895fdc0870878272bb9e09268149a87a6974a274b2184a in .

EXPOSE 8080
CMD [&quot;npm&quot; &quot;start&quot;]
</code></pre>

Is it possible to generate a Dockerfile from an image? I want to know for two reasons:

<ol>
<li>I can download images from the repository but would like to see the recipe that generated them.</li>
<li>I like the idea of saving snapshots, but once I am done it would be nice to have a structured format to review what was done.</li>
</ol>

How to generate a Dockerfile from an image?

虚拟机

容器

Docker

Linux

 镜像可以生成Dockerfile吗？我想知道有两个原因： 我可以从存储库下载图像，但希望看到生成它们的配方。 我喜欢保存快照的想法，但是一旦我完成了，最好能有一个结构化的格式来回顾完成了什么。

问镜像如何生成Dockerfile？
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