DeveloperWiki:Building in a clean chroot
Building in a clean chroot prevents missing dependencies in packages, whether due to unwanted linking or packages missing in the depends array in the PKGBUILD. It also allows users to build a package for the stable repositories (core, extra, community) while having packages from [testing] installed.
To quickly build a package in a clean chroot without any further tinkering, one can use the helper scripts from thepackage.
These helper scripts should be called in the same directory where the PKGBUILD is, just like with makepkg. For instance,
extra-x86_64-build automatically sets up a chroot from a clean chroot matrix in
/var/lib/archbuild, updates it, and builds a package for the extra repository. For multilib builds there is just
multilib-build without an architecture. Consult the table below for information on which script to use when building for a specific repository and architecture.
-c parameter resets the chroot matrix, which can be useful in case of breakage. It is not needed for building in a clean chroot.
|Target repository||Architecture||Build script to use||Pacman configuration file used|
|extra / community||x86_64||extra-x86_64-build||/usr/share/devtools/pacman-extra.conf|
|testing / community-testing||x86_64||testing-x86_64-build||/usr/share/devtools/pacman-testing.conf|
|staging / community-staging||x86_64||staging-x86_64-build||/usr/share/devtools/pacman-staging.conf|
Setting up a chroot
Thepackage provides tools for creating and building within clean chroots. Install it if not done already.
To make a clean chroot, create a directory in which the chroot will reside. For example,
$ mkdir ~/chroot
Now create the chroot (the sub directory
root is required because the
$CHROOT directory will get other sub directories for clean working copies):
$ mkarchroot $CHROOT/root base-devel
$HOME/.bashrcusing the export command if the location is to be repeatedly used.
# btrfs subvolume delete $CHROOT/root.
~/.makepkg.conf to set the packager name and any makeflags. Also adjust the mirrorlist in
$CHROOT/root/etc/pacman.d/mirrorlist and enable the testing repository in
$CHROOT/root/etc/pacman.conf, if desired.
$HOMEvariable are resolved to
/root/by the makechrootpkg script (described below).
Alternatively, provide a custom
makepkg.conf with the following:
$ mkarchroot -C <pacman.conf> -M <makepkg.conf> $CHROOT/root base-devel
makepkg.confduring the initial creation of clean chroot can result in unintended custom adjustments to the chroot environment. Use with caution.
Building in the chroot
Firstly, make sure the base chroot (
$CHROOT/root) is up to date:
$ arch-nspawn $CHROOT/root pacman -Syu
Then, build a package by calling
makechrootpkg in the directory containing its PKGBUILD:
$ makechrootpkg -c -r $CHROOT
makechrootpkgensures that the working chroot (
$CHROOT/$USER) is cleaned before building.
Pre-install required packages
To build a package with dependencies unavailable from the repositories enabled in
$CHROOT/root/pacman.conf, pre-install them to the working chroot with
$ makechrootpkg -c -r $CHROOT -I build-dependency-1.0-1-x86_64.pkg.tar.xz -I required-package-2.0-2-x86_64.pkg.tar.xz
Passing arguments to makepkg
$ makechrootpkg -c -r $CHROOT -- --check
Handling major rebuilds
The cleanest way to handle a major rebuild is to use the [staging] repositories. Build the first package against [extra] and push it to [staging]. Then rebuild all following packages against [staging] and push them there.
If you cannot use [staging], you can build against custom packages using a command like this:
# extra-x86_64-build -- -I ~/packages/foobar/foobar-2-1-any.pkg.tar.xz
You can specify more than one package to be installed using multiple -I arguments.
A simpler, but dirtier way to handle a major rebuild is to install all built packages in the chroot, never cleaning it. Build the first package using:
And build all following packages using:
# makechrootpkg -n -r /var/lib/archbuild/extra-x86_64
Running namcap (the -n argument) implies installing the package in the chroot. *-build also does this by default.
Tips and tricks
Build in tmpfs
If the system has enough RAM, it is possible to specify a tmpfs for the build scripts.
# mkdir -p /mnt/chroots/arch # mount -t tmpfs -o defaults,size=20G tmpfs /mnt/chroots/arch # extra-x86_64-build -c -r /mnt/chroots/arch