RockyRpi/Rocky8_Rpi4_mkimage.sh

#!/bin/bash


# Simple script that runs a Rocky Raspberry pi creation (via appliance-creator), then inserts a UUID to the kernel boot line of the image
# after-the-fact
#
# Usage:  ./Rocky8_Rpi4_mkimage.sh  /path/to/outputfolder/
#
#
# Needs to be run in the same directory as the rocky rpi kickstart, as it relies on it!
#

# Exit with error if we don't have an output directory:
OUTDIR=$1

if [[ -z "$OUTDIR" ]]; then
  echo "Need to run this script with a path to output directory.  Like:  ${0}  /path/to/output/"
  exit 1
fi

mkdir -p "${OUTDIR}"


# Actually create the image.  Our kickstart data should be in the same git repo as this script:
# (This takes a while, especially building on an rpi.  Patience!)
appliance-creator -v -c ./Rocky8_Rpi4.ks -n RockyRpi --version=20210626  --release=1 --vmem=2048 --vcpu=2 --no-compress -o "${OUTDIR}"



# Post appliance-creator sequence to add UUID to the cmdline.txt file under /boot :
# (We don't want to rely on a /dev/ device name, what if a user wants to use a non-sdcard boot mechanism?)

mkdir -p /mnt/tmp

# find the image we just made, and make it available on /dev/maper/loop* devices:
image=$(find "${OUTDIR}"  -iname '*.raw' | head -1)
echo "Getting UUID and inserting to boot from ${image} ...."
kpartx -av  "${image}"

# Get the loop partition; it might be loop0p3, loop1p3, ...
looppart=$(kpartx -l "${image}" | awk '/p3/{print $1}')
# Get the UUID of our root partition (the ext4 one) (UUID=e3984938429 , strip out quotes("), and force upper case)
partuuid=$(blkid | grep "mapper/${looppart}" | head -1 | awk '{gsub(/\"/,"", $NF); print toupper($0)}')

# Mount the /boot partition (swap the 3rd partition for the first):
umount /mnt/tmp
mount /dev/mapper/${looppart/3/1}  /mnt/tmp

# Swap out the "root=" part of cmdline.txt for our "root=UUID=blah"
sed -i "s/root= /root=${partuuid} /"  /mnt/tmp/cmdline.txt

# Debug check to make sure it looks right:
echo "cmdline.txt looks like this, please review:"
cat /mnt/tmp/cmdline.txt

# Finished, unmount and clean loopbacks:
umount /mnt/tmp
kpartx -d "${image}"