How to install Alpine Linux on OVH

2020-06-01

Alpine linux is my favorite Linux distribution. It is — as its slogan says — “Small. Simple. Secure.” which is exactly the aesthetic I want. However many hosting providers, including by favorite OVH doesn’t support it out of the box. We can work around this by net booting another Linux distro, and then installing Alpine from the “inside”. Once completed, and rebooted, you have a clean Alpine install with no traces of the net booted distro that is used in the install.

OVH has three “brands” — with price points targeting entry level, mid level, and pro users.

The screenshots and step by step instructions below are using So You Start but the general technique is applicable to any of the brands, and their control panels are similar.

Lets get started

Login, the first view you see will be the Dashboard, click on Netboot → Rescue → rescue64-pro
Click Next → Confirm
Restart → Confirm
Check your email, they will send you a message with the username and password. It may take several minutes, but is shouldn’t be more than 5 min.

Install Alpine

Login to the net booted rescue system with the username and password from your email. Then copy and paste each code block, along with your own modifications, into the shell.

First we will setup some options for later use:

We need to decide on the host name. I like to name my hosts after tree species, here I am using larch. You will also want to create a non-root user, here I am using my name:

HOST=larch
USER=jordan

You can also select the root and boot file system type, ext4 is a good default.

ROOT_FS=ext4
BOOT_FS=ext4

We need to grab the version of Alpine that we are installing, you can always get the latest from Alpine Linux.org we just want the major and minor version numbers (i.e. 3.12 not 3.12.0)

REL=3.12

We also need to get the version of apk the Alpine Package Manager that matches the version of Alpine we are using. You can look that up in the Alpine package server use the drop downs to select your Alpine version and architecture. For v3.12 it is 2.10.5-r1.

APKV=2.10.5-r1

Alright, we are almost done with the decisions. The last important step is to choose your boot device. You can explore the disks connected to your system with lsblk or lshw -class disk. We are going to keep things simple and just use the first hard drive.

DEV=/dev/sda
BOOT_DEV=${DEV}1
ROOT_DEV=${DEV}2
ROOT=/mnt
BOOT=/mnt/boot

We’ll also need these, but you generally shouldn’t need to edit them.

PATH=/bin:/sbin:/usr/bin:/usr/sbin
FEATURES="ata base ide scsi usb virtio $ROOT_FS"
MODULES="sd-mod,usb-storage,$ROOT_FS"
MIRROR=http://dl-cdn.alpinelinux.org/alpine
REPO=$MIRROR/v$REL/main
ARCH=$(uname -m)

Alright, we are ready to roll!

Setup partitions:

sgdisk --zap-all $DEV
sgdisk --new 1:0:+512M $DEV
# the type is from sgdisk --list-type 8300 is Linux filesystem
sgdisk --typecode 1:8300 $DEV
sgdisk --change-name 1:boot $DEV
sgdisk --new 2:0:0 $DEV # zero means max here
sgdisk --typecode 2:8300 $DEV
sgdisk --change-name 2:root $DEV
sgdisk --attributes 1:set:2 $DEV

Format the disk

# -m reserved-blocks-percentage
# -q Quiet execution.
# -L new-volume-label
mkfs.$BOOT_FS -m 0 -q -L boot $BOOT_DEV
mkfs.$ROOT_FS -q -L root $ROOT_DEV
mount $ROOT_DEV $ROOT
mkdir $BOOT
mount $BOOT_DEV $BOOT

Grab apk

curl -s $MIRROR/v$REL/main/$ARCH/apk-tools-static-${APKV}.apk | tar xz

You may get some errors like:

# tar: Ignoring unknown extended header keyword 'APK-TOOLS.checksum.SHA1'
# tar: Ignoring unknown extended header keyword 'APK-TOOLS.checksum.SHA1'

what is fine, just proceed.

Install the base system

./sbin/apk.static \
    --repository $REPO \
    --update-cache \
    --allow-untrusted \
    --root $ROOT \
    --initdb add alpine-base syslinux dhcpcd linux-lts

In the next sections it is important to copy and paste the entire section as one piece.

Setup fstab

cat << EOF > $ROOT/etc/fstab
$ROOT_DEV / $ROOT_FS defaults,noatime 0 0
$BOOT_DEV /boot $BOOT_FS defaults 0 2
EOF

Package repository and networking

echo $REPO > $ROOT/etc/apk/repositories
cat /etc/resolv.conf > $ROOT/etc/resolv.conf

Booting

cat << EOF > $ROOT/etc/update-extlinux.conf
overwrite=1
vesa_menu=0
default_kernel_opts="quiet"
modules=$MODULES
root=$ROOT_DEV
verbose=0
hidden=1
timeout=1
serial_port=
serial_baud=115200
password=''
EOF

More networking…

cat << EOF > $ROOT/etc/network/interfaces
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp
  hostname $HOST
EOF

Now we will mount the newly created system and finalize setting it up.

Mount

mount --bind /proc $ROOT/proc
mount --bind /dev $ROOT/dev
mount --bind /sys $ROOT/sys

Setup

chroot $ROOT /bin/sh -x << CHROOT
apk update
apk add openssh

setup-hostname -n $HOST

rc-update -q add devfs sysinit
rc-update -q add dmesg sysinit
rc-update -q add mdev sysinit
rc-update -q add hwdrivers sysinit

rc-update -q add hwclock boot
rc-update -q add modules boot
rc-update -q add sysctl boot
rc-update -q add hostname boot
rc-update -q add bootmisc boot
rc-update -q add syslog boot
rc-update -q add networking boot
rc-update -q add urandom boot
rc-update -q add dhcpcd boot

rc-update -q add mount-ro shutdown
rc-update -q add killprocs shutdown
rc-update -q add savecache shutdown

rc-update -q add acpid default
rc-update -q add crond default
rc-update -q add sshd default

echo features=\""$FEATURES"\" > /etc/mkinitfs/mkinitfs.conf

extlinux -i /boot
dd bs=440 conv=notrunc count=1 if=/usr/share/syslinux/gptmbr.bin of=$DEV
update-extlinux
CHROOT

Lets set the root password and our user’s password:

chroot $ROOT passwd
chroot $ROOT adduser -s /bin/ash -D $USER
chroot $ROOT passwd $USER

And finally we unmount

umount $ROOT/proc
umount $ROOT/dev
umount $ROOT/sys
umount $BOOT
umount $ROOT

Then logout of your SSH session.

Return to the Dashboard
Click Netboot → Hard disk → Next → Confirm
Restart
Wait for an email letting you know it has restarted.
You can now login with the username and password that you set earlier — but not the root user as remote login as root is disabled.

Good luck!