Arch Linux docker

Sometimes it is necessary to create docker containers in an isolated environment (without an external docker hub, external software repositories and internet access at all). With a local Arch Linux mirror you have almost all for this.

Setup docker

sudo pacman -Sy docker
sudo usermod -aG docker $USER
sudo systemctl start docker

Build docker images from the Arch Linux base ROOTFS

Personally I don’t like this way. Arch Linux base image is much bigger comparing to Alpine, Ubuntu or many other vendors. It’s size is about 500MB and it contains tons of unnecessary files.

Pre-conditions

System with Arch Linux installed (see Arch Linux install)
There is a local pacman mirror (see Arch Linux mirror)
Arch Linux ROOTFS downloaded from the “gitlab.archlinux.org”:

wget -c --content-disposition -P /mirror/archlinux-docker \
  https://gitlab.archlinux.org/archlinux/archlinux-docker/-/package_files/357/download 
wget -c --content-disposition -P /mirror/archlinux-docker \
  https://gitlab.archlinux.org/archlinux/archlinux-docker/-/package_files/358/download

Import base image

docker import /mirror/archlinux-docker/base-20201222.0.11875.tar.xz archbase:20201222
docker images

#REPOSITORY   TAG        IMAGE ID       CREATED         SIZE
#archbase     20201222   09a43bc2471b   4 minutes ago   407MB

docker run --rm -it archbase:20201222 bash

Create images

Build docker build -t myarch . from this Dockerfile:

FROM archbase:20201222

RUN echo 'Server=http://172.17.0.1/mirror/archlinux/$repo/os/$arch' >/etc/pacman.d/mirrorlist

RUN pacman -Suy --noconfirm --needed nginx

Arch Linux docker images from scratch

What would be better than something created from scratch?

It is pretty simple to create a base image based on Arch Linux.

What is a base software:

almost all packages require “glibc” and “gcc-libs” (224MB)
also it is nice to have “coreutils” and “bash” (+65MB, 289MB)
pacman, to install packages in next images (+89MB, 378MB)
plus optionally “python” (+87MB, 465MB)
the total size of this base software is about 465MB
but it is possible to reduce it a bit by excluding some files via pacman (-109MB, 356MB)
and reduce it a bit more by removing some files (-7MB, 349MB)

Prepare files

FILES=myarchbase-files

rm -rvf $FILES
mkdir -pv $FILES/etc/pacman.d $FILES/var/lib/pacman

cat >$FILES/etc/locale.conf <<EOF
LANG=en_US.UTF-8
LC_ALL=en_US.UTF-8
EOF

cat >$FILES/etc/locale.gen <<EOF
en_US.UTF-8 UTF-8
EOF

cat >$FILES/etc/pacman.d/mirrorlist <<EOF
Server = http://mirror.local/mirror/archlinux/\$repo/os/\$arch
EOF

cat >$FILES/etc/pacman.conf <<EOF
[options]
Architecture = x86_64
SigLevel = Never
Include = /etc/pacman.d/noextract

[core]
Include = /etc/pacman.d/mirrorlist

[extra]
Include = /etc/pacman.d/mirrorlist

[community]
Include = /etc/pacman.d/mirrorlist
EOF

cat >$FILES/etc/pacman.d/noextract <<EOF
# Exclude unnecessary files
NoExtract = usr/include/*
NoExtract = usr/share/doc/*
NoExtract = usr/share/i18n/charmaps/* 
NoExtract = !usr/share/i18n/charmaps/UTF-8.gz
NoExtract = usr/share/i18n/locales/*
NoExtract = !usr/share/i18n/locales/en_US 
NoExtract = !usr/share/i18n/locales/en_GB
NoExtract = !usr/share/i18n/locales/i18n*
NoExtract = !usr/share/i18n/locales/iso*
NoExtract = !usr/share/i18n/locales/translit*
NoExtract = usr/share/iana-etc/*
NoExtract = usr/share/info/*
NoExtract = usr/share/gtk-doc/*
NoExtract = usr/share/licenses/*
#NoExtract = usr/share/locale/* 
#NoExtract = !usr/share/locale/en_GB/*
#NoExtract = !usr/share/locale/en_US/*
#NoExtract = !usr/share/locale/locale.alias
NoExtract = usr/share/man/*
NoExtract = usr/share/pixmaps/*
NoExtract = usr/share/readline/*

# Exclude prepared files
NoExtract = etc/locale.conf
NoExtract = etc/locale.gen
NoExtract = etc/pacman.conf
NoExtract = etc/pacman.d/mirrorlist
NoExtract = etc/pacman.d/noextract
EOF

Create base filesystem

FILES=myarchbase-files
OUTPUT=/tmp/myarchbase

sudo rm -rf $OUTPUT
sudo mkdir -pv $OUTPUT/var/lib/pacman
sudo cp -r $FILES/* $OUTPUT/
#sudo pacman -Svy --noconfirm --needed --sysroot $OUTPUT glibc gcc-libs coreutils bash pacman sed less
pacstrap -cGiM $OUTPUT glibc gcc-libs coreutils bash pacman sed less
sudo du -sh $OUTPUT
sudo chroot $OUTPUT rm -rf /var/cache/pacman/pkg/* /var/lib/pacman/sync/*
sudo chroot $OUTPUT locale-gen
sudo du -sh $OUTPUT

Import base filesystem as base image

sudo tar -cJf $OUTPUT.tar.xz $OUTPUT
sudo tar -cjf /tmp/vault-base.tbz -C /tmp/vault-base .
docker import /tmp/myarchbase myarchbase
docker images
docker run --rm -it myarchbase bash