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I'm creating minimalistic ubuntu os image for Azure and in the Docker file I'm trying to pull the tar and build it from scratch ( "FROM scratch.."). I see there are various tar available here and not sure which one should I be used - http://cloud-images.ubuntu.com/minimal/releases/bionic/release-20201210/. Need some advice on this.

Dev MK
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1 Answers1

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according to https://ubuntu.com/blog/minimal-ubuntu-released

On Dockerhub, the new Ubuntu 18.04 LTS image is now the new Minimal Ubuntu 18.04 image. Launching a Docker instance with docker run ubuntu:18.04 therefore launches a Docker instance with the latest Minimal Ubuntu.

you can find the docker hub for ubuntu here : https://hub.docker.com/_/ubuntu

for 18.04 this is the dockerfile ubuntu uses to build the docker image (lcick on bionic in this page)

bionic dockerfile

https://github.com/tianon/docker-brew-ubuntu-core/blob/74249faf47098bef2cedad89696bfd1ed521e019/bionic/Dockerfile

i.e.

FROM scratch
ADD ubuntu-bionic-core-cloudimg-amd64-root.tar.gz /

a few minor docker-specific tweaks


see https://github.com/docker/docker/blob/9a9fc01af8fb5d98b8eec0740716226fadb3735c/contrib/mkimage/debootstrap


RUN set -xe 

    \


https://github.com/docker/docker/blob/9a9fc01af8fb5d98b8eec0740716226fadb3735c/contrib/mkimage/debootstrap#L40-L48


&& echo '#!/bin/sh' > /usr/sbin/policy-rc.d \
&& echo 'exit 101' >> /usr/sbin/policy-rc.d \
&& chmod +x /usr/sbin/policy-rc.d \
\



https://github.com/docker/docker/blob/9a9fc01af8fb5d98b8eec0740716226fadb3735c/contrib/mkimage/debootstrap#L54-L56


&& dpkg-divert --local --rename --add /sbin/initctl \
&& cp -a /usr/sbin/policy-rc.d /sbin/initctl \
&& sed -i 's/^exit.*/exit 0/' /sbin/initctl \
\



https://github.com/docker/docker/blob/9a9fc01af8fb5d98b8eec0740716226fadb3735c/contrib/mkimage/debootstrap#L71-L78


&& echo 'force-unsafe-io' > /etc/dpkg/dpkg.cfg.d/docker-apt-speedup \
\



https://github.com/docker/docker/blob/9a9fc01af8fb5d98b8eec0740716226fadb3735c/contrib/mkimage/debootstrap#L85-L105


&& 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 \
\



https://github.com/docker/docker/blob/9a9fc01af8fb5d98b8eec0740716226fadb3735c/contrib/mkimage/debootstrap#L109-L115


&& echo 'Acquire::Languages "none";' > /etc/apt/apt.conf.d/docker-no-languages \
\



https://github.com/docker/docker/blob/9a9fc01af8fb5d98b8eec0740716226fadb3735c/contrib/mkimage/debootstrap#L118-L130


&& echo 'Acquire::GzipIndexes "true"; Acquire::CompressionTypes::Order:: "gz";' > /etc/apt/apt.conf.d/docker-gzip-indexes \
\



https://github.com/docker/docker/blob/9a9fc01af8fb5d98b8eec0740716226fadb3735c/contrib/mkimage/debootstrap#L134-L151


&& echo 'Apt::AutoRemove::SuggestsImportant "false";' > /etc/apt/apt.conf.d/docker-autoremove-suggests




verify that the APT lists files do not exist


RUN [ -z "$(apt-get indextargets)" ]


(see https://bugs.launchpad.net/cloud-images/+bug/1699913)


make systemd-detect-virt return "docker"


See: https://github.com/systemd/systemd/blob/aa0c34279ee40bce2f9681b496922dedbadfca19/src/basic/virt.c#L434


RUN mkdir -p /run/systemd && echo 'docker' > /run/systemd/container


CMD ["/bin/bash"]
Koen
  • 1,277