Ubuntu14.04与Ubuntu12.04泊坞窗图像

我有一些基于ubuntu12.04映像的docker镜像。 我想迁移其中的一些基于Ubuntu14.04。 但是ubuntu14.04映像比ubuntu12.04映像大了将近120MB。

任何人都知道为什么和如何减lessubuntu14.04图像

运行docker images

 myregistry/ubuntu 14.04 xxx xxx 225.4 MB myregistry/ubuntu 12.04 xxx xxx 103.9 MB 

Answer 1

我看到的第一个问题是，你没有告诉我们你是如何到达你所拥有的图像的。 它们来自非根registry（“myregistry”），并且您从复制/粘贴练习中省略了散列。

当我下载这些图像，这是我看到的：

 WineSoaked$ docker pull ubuntu:12.04 Pulling repository ubuntu b45a6cbea6d1: Download complete 511136ea3c5a: Download complete 0b825e3a3d82: Download complete 3327dfd9dc7d: Download complete 4e284c9e0a9e: Download complete ae9570f7a92a: Download complete acc75c8f0e1d: Download complete WineSoaked$ docker pull ubuntu:14.04 Pulling repository ubuntu 6b4e8a7373fe: Download complete 511136ea3c5a: Download complete b18d0a2076a1: Download complete 67b66f26d423: Download complete 25c4824a5268: Download complete 8b1c48305638: Download complete c900195dcbf3: Download complete WineSoaked$ docker images REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE ubuntu 14.04 6b4e8a7373fe 6 days ago 194.9 MB ubuntu 12.04 b45a6cbea6d1 6 days ago 112.3 MB 

你会注意到每个pull中的第二个hash是相同的。 这是build立在这个基础上的基础。 其余的与用于构build它们的dockerfiles有关。 我们去看看吧？

这里是12.04的Dockerfile ：

 FROM scratch ADD precise-core-amd64.tar.gz / # a few minor docker-specific tweaks # see https://github.com/dotcloud/docker/blob/master/contrib/mkimage/debootstrap RUN echo '#!/bin/sh' > /usr/sbin/policy-rc.d \ && echo 'exit 101' >> /usr/sbin/policy-rc.d \ && chmod +x /usr/sbin/policy-rc.d \ \ && dpkg-divert --local --rename --add /sbin/initctl \ && cp -a /usr/sbin/policy-rc.d /sbin/initctl \ && sed -i 's/^exit.*/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 || 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 || 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 # delete all the apt list files since they're big and get stale quickly RUN rm -rf /var/lib/apt/lists/* # this forces "apt-get update" in dependent images, which is also good # enable the universe RUN sed -i 's/^#\s*\(deb.*universe\)$/\1/g' /etc/apt/sources.list # upgrade packages for now, since the tarballs aren't updated frequently enough RUN apt-get update && apt-get dist-upgrade -y && rm -rf /var/lib/apt/lists/* # overwrite this with 'CMD []' in a dependent Dockerfile CMD ["/bin/bash"] 

Dockerfile中的每个命令都对应于散列之一，这些散列是构成AUFS文件系统的中间映像。 以机智：

• 511136ea3c5a对应于FROM scratch
• 0b825e3a3d82对应于ADD precise-core-amd64.tar.gz …
• 3327dfd9dc7d与史诗般的长跑
• 4e284c9e0a9e随RUN rm -rf /var/lib/apt/lists/*
• ae9570f7a92a使用RUN sed -i 's/^#\s*\(deb.*universe\)$/\1/g' /etc/apt/sources.list etc/apt/sources.list
• acc75c8f0e1d会RUN apt-get update && apt-get dist-upgrade -y && rm -rf /var/lib/apt/lists/*并且b45a6cbea6d1对应于生成的图像。

你可以基于它的Dockerfile来分解14.04镜像：

 FROM scratch ADD trusty-core-amd64.tar.gz / # a few minor docker-specific tweaks # see https://github.com/dotcloud/docker/blob/master/contrib/mkimage/debootstrap RUN echo '#!/bin/sh' > /usr/sbin/policy-rc.d \ && echo 'exit 101' >> /usr/sbin/policy-rc.d \ && chmod +x /usr/sbin/policy-rc.d \ \ && dpkg-divert --local --rename --add /sbin/initctl \ && cp -a /usr/sbin/policy-rc.d /sbin/initctl \ && sed -i 's/^exit.*/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 || 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 || 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 # delete all the apt list files since they're big and get stale quickly RUN rm -rf /var/lib/apt/lists/* # this forces "apt-get update" in dependent images, which is also good # enable the universe RUN sed -i 's/^#\s*\(deb.*universe\)$/\1/g' /etc/apt/sources.list # upgrade packages for now, since the tarballs aren't updated frequently enough RUN apt-get update && apt-get dist-upgrade -y && rm -rf /var/lib/apt/lists/* # overwrite this with 'CMD []' in a dependent Dockerfile CMD ["/bin/bash"] 

所以，在Dockerfile中，我认为14.04更大的主要原因是它们的基础tarball比较大。 12.04的tarball是〜39MB，而14.04 tarball是〜66MB。 你可以下载和gunzip他们得到他们的真实大小，但我认为这让你开始了解的道路上。

这可以使用docker history命令来确认：

 $ docker history ubuntu:12.04 IMAGE CREATED CREATED BY SIZE b45a6cbea6d1 6 days ago /bin/sh -c #(nop) CMD [/bin/bash] 0 B acc75c8f0e1d 6 days ago /bin/sh -c apt-get update && apt-get dist-upg 8.5 MB ae9570f7a92a 6 days ago /bin/sh -c sed -i 's/^#\s*\(deb.*universe\)$/ 1.911 kB 4e284c9e0a9e 6 days ago /bin/sh -c rm -rf /var/lib/apt/lists/* 0 B 3327dfd9dc7d 6 days ago /bin/sh -c echo '#!/bin/sh' > /usr/sbin/polic 156.2 kB 0b825e3a3d82 6 days ago /bin/sh -c #(nop) ADD file:f66a301611d5f2b8e4 103.7 MB 511136ea3c5a 16 months ago 0 B $ docker history ubuntu:14.04 IMAGE CREATED CREATED BY SIZE 6b4e8a7373fe 6 days ago /bin/sh -c #(nop) CMD [/bin/bash] 0 B c900195dcbf3 6 days ago /bin/sh -c apt-get update && apt-get dist-upg 2.178 MB 8b1c48305638 6 days ago /bin/sh -c sed -i 's/^#\s*\(deb.*universe\)$/ 1.895 kB 25c4824a5268 6 days ago /bin/sh -c rm -rf /var/lib/apt/lists/* 0 B 67b66f26d423 6 days ago /bin/sh -c echo '#!/bin/sh' > /usr/sbin/polic 194.5 kB b18d0a2076a1 6 days ago /bin/sh -c #(nop) ADD file:57743b1a50a2440168 192.6 MB 511136ea3c5a 16 months ago 0 B