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) while having packages from core-testing or extra-testing installed.
To quickly build a package in a clean chroot without any further tinkering, one can use the helper scripts from the devtools package.
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.
- core is omitted because those packages are required to go through core-testing first before landing in core.
- If the objective is to build a core package for your own local usage, it may be desirable to use the stable repositories instead of the testing ones. In this case you may simply use the extra build scripts.
|Target repository||Architecture||Build script to use||Pacman configuration file used|
|core-testing / extra-testing||x86_64||extra-testing-x86_64-build||/usr/share/devtools/pacman.conf.d/extra-testing.conf|
|core-staging / extra-staging||x86_64||extra-staging-x86_64-build||/usr/share/devtools/pacman.conf.d/extra-staging.conf|
Setting up a chroot
The devtools package 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
- One can also define the
$HOME/.bashrcusing the export command if the location is to be repeatedly used.
- On btrfs, the chroot is created as a subvolume, so you have to remove it by removing the subvolume by running
btrfs subvolume delete $CHROOT/rootas 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 repositories 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
To pass arguments to makepkg, list them after an end-of-options marker; e.g., to force a
$ 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
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 devtools build scripts.
# mount --mkdir -t tmpfs -o defaults,size=20G tmpfs /mnt/chroots/arch # extra-x86_64-build -c -r /mnt/chroots/arch