Software management

2022-07-04T12:29:59Z

Gregor: Adding a description of how to use the chrooted glibc directly from the host, and cleaning up a bit

If you want to run [https://www.gnu.org/software/libc/ glibc] programs in Alpine Linux, there are a few ways of doing so. You can install the [https://git.adelielinux.org/adelie/gcompat gcompat] compatibility layer, you can install glibc alongside [https://musl.libc.org/ musl] (manually, as it isn't packaged), or you could do it the easy way and use either Flatpak (the easiest) or a chroot.<br>

Because there are different use cases, this is just a slight overview about what's possible and what's sensible.<br>

= Your options =

== gcompat ==

[https://git.adelielinux.org/adelie/gcompat gcompat] is the go-to compatibility layer for Alpine users.

{{cmd|apk add gcompat}}

After that you run your binaries as normal.

== Flatpak ==

Flatpak is by far the easiest method of running any graphical glibc program on Alpine.
Firstly install it.

{{cmd|doas apk add flatpak}}

Then you can run any Flatpak application:

{{cmd|flatpak run <flatpak name>}}

It is recommended to enable [https://flathub.org Flathub] using its instructions [https://flatpak.org/setup/Alpine/ here], as most glibc programs you might need will be packaged there.

You can then install applications from it, for example:

{{cmd|flatpak install com.valvesoftware.Steam}}

== Chroot ==

An option that's easier to generalize to other glibc applications is installing a glibc-based distribution into a chroot. You can then either chroot into it, or use a symlink and some configuration to make its glibc (and associated libraries) usable from Alpine.

After setting up a chroot using any of the methods described below, the loader can be set up in Alpine like so (these instructions are for a Debian chroot in /var/chroots/debian, on x86_64, but can be adapted to other systems by using the appropriate paths):

mkdir -p /lib64
ln -s /var/chroots/debian/lib/x86_64-linux-gnu/ld-2.33.so /lib64
printf '/var/chroots/debian/lib/x86_64-linux/gnu\n/var/chroots/debian/usr/lib/x86_64-linux-gnu\n' > /etc/ld.so.conf
/var/chroots/debian/sbin/ldconfig

=== Gentoo Linux ===

Select a stage3 from [https://www.gentoo.org/downloads/ here] and portage latest from [https://www.gentoo.org/downloads/mirrors/ here] at gentoo/snapshots/portage-latest.tar.xz.

First,

sudo apk add xz

Enter the chroot:
mkdir ~/chroot
cd ~/chroot
tar -xvf stage3-*.tar.xz
tar -xvf portage-latest.tar.xz
mv portage usr
sudo mount --bind /dev dev
sudo mount --bind /sys sys
sudo mount -t proc proc proc
cp /etc/resolv.conf etc
sudo chroot . /bin/bash

And voilà, you have your working Gentoo chroot!<br>

You can now take a look at [https://wiki.gentoo.org/wiki/Handbook:Main_Page Gentoo's Handbook] to find out how you can configure and install your system, or simply extract/copy the program you need to run in your chroot enviroment and execute it.

Here is a wrapper script that is similar to <code>arch-chroot</code> when you frequently reuse this chroot:

Also, create an account with the same user name as host current user to the chroot or make changes to the userspec option to chroot line.

{{Cat|gentoo-chroot.sh|<nowiki>!/bin/bash
CHROOT_PATH="/home/$USER/chroot"
cd $CHROOT_PATH
mount | grep $CHROOT_PATH/dev || sudo mount --bind /dev dev
mount | grep $CHROOT_PATH/sys || sudo mount --bind /sys sys
mount | grep $CHROOT_PATH/proc || sudo mount -t proc proc proc
cp /etc/resolv.conf etc
sudo chroot --userspec=$USER:users . /bin/bash
echo "You must manually unmount $CHROOT_PATH/dev, $CHROOT_PATH/sys, $CHROOT_PATH/proc."
</nowiki>
}}

Do at <code>chmod +x gentoo-chroot.sh</code> to get it to work.

=== Arch Linux ===

Either use '''pacstrap''' (included with the arch-install-scripts package) or an Arch bootstrap image:

sudo apk add arch-install-scripts
mkdir ~/chroot && cd ~/chroot
curl -O https://mirrors.edge.kernel.org/archlinux/iso/latest/archlinux-bootstrap-2021.04.01-x86_64.tar.gz{{dead link}}
sudo tar xzf archlinux-bootstrap-2021.04.01-x86_64.tar.gz && rm archlinux-bootstrap-2021.04.01-x86_64.tar.gz
sudo sed -i '/evowise/s/^#//' root.x86_64/etc/pacman.d/mirrorlist
sudo sed -i '/CheckSpace/s/^/#/' root.x86_64/etc/pacman.conf
sudo arch-chroot root.x86_64
[chroot]# pacman-key --init
[chroot]# pacman-key --populate archlinux

Once that is done, update the system and install the desired package(s) (denoted by ''"foo"'' in this example):

[chroot]# pacman -Syu ''foo''

=== Debian ===

Use the provided debootstrap package to create the Debian chroot. <code>--arch</code> is optional, depending of your needs.

On the '''linux-grsec''' kernel, you will need to relax chroot limitations:

sudo apk add debootstrap
for i in /proc/sys/kernel/grsecurity/chroot_*; do echo 0 | sudo tee $i; done
mkdir ~/chroot
sudo debootstrap --arch=i386 wheezy ~/chroot http://http.debian.net/debian/
for i in /proc/sys/kernel/grsecurity/chroot_*; do echo 1 | sudo tee $i; done
sudo chroot ~/chroot /bin/bash

You can now use <code>apt-get</code> to install needed packages.

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