Setting up the build environment in a chroot

Introduction

You will need a few Gigabytes to have enough pace for kernel compiling and storing all the binary packages and iso image.

This page is divided into 2 main sections

• Create a build environment
• Update a existing environment

Create a build environment

The Build Environment (called BE from now on) could be any of the following...

• Created on a existing 2.6 kernel
• A disk-based Alpine

Create BE on existing 2.6 kernel

We are setting up our BE in chroot.

Note: The variables below:

• ${mirror} = Should be replaced with one of the available alpine-mirrors.
• ${build_dir} = You can name it whatever you like.

Lets start by geting the latest apk static binary:

wget ${mirror}/apk.static
chmod +x ./apk.static

We are setting up a basic chroot:

mkdir ${build_dir}
./apk.static --repo ${mirror}/packages/core --root $PWD/${build_dir} add --initdb build-base git abuildv
mkdir -p ./${build_dir}/proc
mount --bind /proc ./${build_dir}/proc

Lets setup our needed devices:

mknod -m 666 ./${build_dir}/dev/full c 1 7
mknod -m 777 ./${build_dir}/dev/null c 1 3
mknod -m 666 ./${build_dir}/dev/ptmx c 5 2
mknod -m 644 ./${build_dir}/dev/random c 1 8
mknod -m 644 ./${build_dir}/dev/urandom c 1 9
mknod -m 666 ./${build_dir}/dev/zero c 1 5
mknod -m 666 ./${build_dir}/dev/tty c 5 0

We need or dns servers and root dir:

cp /etc/resolv.conf ./${build_dir}/etc/
mkdir -p ./${build_dir}/root

We are setting up apk mirrors:

mkdir -p ./${build_dir}/etc/apk
echo "${mirror}/packages/core" > ./${build_dir}/etc/apk/repositories
echo "${mirror}/packages/extra" >> ./${build_dir}/etc/apk/repositories

At this point you should be able to enter your chroot:

chroot ./${build_dir} /bin/sh

Create BE on HD-based Alpine

First you need to boot a alpine-test.iso
Ether you do it on a standalone computer or in a virtual machine.

Preparing KVM (temporary notes)

I chose to setup a HD-based Alpine in a virtual machine on my Ubuntu 8.10.
(Notes: This section about setting up KVM should probably be removed later on - it's mostly there to help me get started).

apt-get install kvm ###This installs KVM###
kvm-img create alpine-kvm_hd.img 5G ###Create a KVM-disk###
wget http://distrib-coffee.ipsl.jussieu.fr/pub/linux/alpine/alpine/v1.9/alpine-test.iso ###Download iso###

Before we boot our kvm-qemu we need to prepare it for networking by following the Running_Alpinelinux_As_a_QEMU_networked_Guest documents.
This assumes you created a file qemu-ifup according to the wiki-doc just mentioned.

sudo kvm -cdrom alpine-test.iso -boot d -net tap,vlan=0,ifname=tap0,script=./qemu-ifup -net nic,vlan0 alpine-kvm_hd.img

At this point we started a virtual machine running a clean Alpine.
Now we need to prepare this for networking, etc.

Temporary note: For some reason I can't get networking to work in my kvm-qemu box. Complaining about tun/tap on my host. Need to fix this.

Prepare the clean Alpine

At this point you should have a fresh alpine-box.