Install Alpine On Raspberry Pi USB Disk

Prepare SD card and USB hard disk

SD card which more than 128M needed, format it as fat32. Make partition from USB hard disk and format it as ext4.

Download : http://dl-cdn.alpinelinux.org/alpine/v3.6/releases/armhf/alpine-rpi-3.6.2-armhf.tar.gz and decompress it on SD card.

Then plug HDMI, keyboard and network cables. Insert the SD-card into the Raspberrypi and power on.

Run instructions below

So launch instructions as follows:

setup-alpine (adjust keymap, timezone, networking)
mount /dev/sda1 /mnt
setup-disk -m sys /mnt

mkdir media/mmcblk0p1
mount -o remount,rw /dev/mmcblk0p1 /media/mmcblk0p1
rm /media/mmcblk0p1/boot/*
mv /mnt/boot/* /media/mmcblk0p1/boot

rm -rf /mnt/boot
ln -s /media/mmcblk0p1 boot
sed -i 's/^/root=\/dev\/sda1 /' /media/mmcblk0p1/cmdline.txt

echo "/dev/mmcblk0p1 /media/mmcblk0p1 vfat ro 0 0" >> /mnt/etc/fstab
sed -i '/cdrom/d' /mnt/etc/fstab
sed -i '/floppy/d' /mnt/etc/fstab
sed -i '/edge/!s/^#//' /mnt/etc/apk/repositories

reboot

After reboot execute the following instructions :

rc-update del hwclock boot
rc-update add swclock boot
rc-update add wpa_supplicant boot ( only if your Raspberrypi has wifi on board )