Add script for automatic disk extension + swap creation

alpine.sh

@@ -46,13 +46,11 @@ echo -n 'password' | cryptsetup open --type luks /dev/sda2 system
 # Set up LVM
 pvcreate /dev/mapper/system
 vgcreate vg0 /dev/mapper/system
-lvcreate -L 4G vg0 -n swap
 lvcreate -l 100%FREE vg0 -n root
 
 # Format
 mkfs.ext4 -m0 /dev/sda1
 mkfs.ext4 -m1 /dev/vg0/root
-mkswap /dev/vg0/swap
 
 # Mount
 mount -t ext4 /dev/vg0/root /mnt
@@ -97,7 +95,6 @@ dd bs=440 count=1 conv=notrunc if=/mnt/usr/share/syslinux/mbr.bin of=/dev/sda
 # Unmount and shut down
 umount /mnt/boot
 umount /mnt
-swapoff -a
 vgchange -a n
 cryptsetup luksClose system
 poweroff

basic.sh

@@ -5,7 +5,7 @@ SOURCE_DIR=$(realpath $(dirname "${0}"))/basic
 
 # Install packages
 apk --no-cache add --virtual .useful git file htop less openssh-server openssh-sftp-server
-apk --no-cache add curl docker gettext kbd-misc libressl python3 py3-bcrypt py3-cffi py3-dnspython py3-jinja2 py3-requests py3-six py3-werkzeug nginx
+apk --no-cache add curl docker e2fsprogs-extra gettext kbd-misc libressl python3 py3-bcrypt py3-cffi py3-dnspython py3-jinja2 py3-requests py3-six py3-werkzeug nginx util-linux
 
 # Copy profile files and settings
 mkdir -p /root/.config/htop /root/.ssh
@@ -17,6 +17,7 @@ cp ${SOURCE_DIR}/root/.config/htop/htoprc /root/.config/htop/htoprc
 cp ${SOURCE_DIR}/boot/extlinux.conf /boot/extlinux.conf
 cp ${SOURCE_DIR}/boot/spotter.txt /boot/spotter.txt
 cp ${SOURCE_DIR}/etc/inittab /etc/inittab
+cp ${SOURCE_DIR}/sbin/extend-disk /sbin/extend-disk
 >/etc/motd
 
 # Enable support for Czech characters
@@ -47,7 +48,7 @@ cp -r ${SOURCE_DIR}/srv/spotter /srv/spotter
 ln -s /srv/spotter/cli.py /usr/bin/spotter-appmgr
 
 # Configure services
-for SERVICE in consolefont crond nginx ntpd sshd spotter-appmgr; do
+for SERVICE in consolefont crond nginx ntpd sshd spotter-appmgr swap; do
     rc-update add ${SERVICE} boot
     service ${SERVICE} start
 done

basic/etc/inittab

@@ -2,6 +2,7 @@
 
 ::sysinit:/sbin/openrc sysinit >/dev/null 2>&1
 ::sysinit:/sbin/openrc boot >/dev/null 2>&1
+::wait:/sbin/extend-disk >/dev/null 2>&1
 ::wait:/sbin/openrc default >/dev/null 2>&1
 
 # Set up getty

basic/sbin/extend-disk

@@ -0,0 +1,39 @@
+#!/bin/sh
+set -e
+
+# No resizing with less than 10k unused blocks
+BLOCKS_FREE=$(/usr/bin/awk '/sda$/ {blocks = $3} /sda\d/ {blocks -= $3} END {print blocks}' /proc/partitions)
+[ ${BLOCKS_FREE} -lt 10240 ] && exit 0
+
+# Resize physical partition
+# Force busybox fdisk as util-linux fdisk breaks subsequent partx command
+cat <<EOF | /bin/busybox fdisk /dev/sda || /bin/true
+d
+2
+n
+p
+2
+
+
+t
+2
+8e
+w
+EOF
+
+# Re-read partition table
+/usr/sbin/partx -u /dev/sda2
+
+# Resize dmcrypt and LVM PV
+/sbin/cryptsetup resize system
+/sbin/pvresize /dev/mapper/system
+
+# Create swap if it doesn't exist
+if [ ! -e /dev/vg0/swap ]; then
+    /sbin/lvcreate -L 4G vg0 -n swap
+    /sbin/mkswap /dev/vg0/swap
+fi
+
+# Extend LV and underlying filesystem
+/sbin/lvextend -l +100%FREE vg0/root
+/usr/sbin/resize2fs /dev/vg0/root