armvmstuff.sh

#!/bin/bash

# install prerequsits as needed
sudo apt update
sudo apt install -y cloud-utils qemu-utils

# lets put the stuff here
mkdir ~/ubuntu2004cloudimg
cd ~/ubuntu2004cloudimg

# download the ubuntu cloud image
if ! [[ -f focal-server-cloudimg-arm64.img ]]; then
  wget https://cloud-images.ubuntu.com/focal/20201123/focal-server-cloudimg-arm64.img
fi

# mount the cloud image to extract kernel and such
sudo modprobe nbd max_part=1
sudo qemu-nbd --connect=/dev/nbd0 focal-server-cloudimg-arm64.img
sudo mkdir -p /mnt/nbd
sleep 8
sudo mount /dev/nbd0p1 /mnt/nbd/ -o noatime

if [[ -d /mnt/nbd/boot ]]; then
    ls /mnt/nbd/boot
else
    echo "mount failed.."
    exit 1
fi

# extract the needed files
sudo cat /mnt/nbd/boot/vmlinuz-5.4.0-54-generic | gzip -d > vmlinuz-5.4.0-54-generic
sudo cp /mnt/nbd/boot/initrd.img-5.4.0-54-generic initrd.img-5.4.0-54-generic
sudo chown $USER:$USER ./* 

# hack in a root password of ubuntu
SHADOW=$(sudo cat /mnt/nbd/etc/shadow | grep -v root)
echo 'root:$6$/14.3JvFwhEHViIT$1N37V7rNApmlieA5FE1F1zCfucy6vg0RCr6.qVrJHxtC8Ek4e0JH1HAdvLkAMxrFpa8x.Vb0IfP9OoIEWKwFf/:18589:0:99999:7:::' | sudo tee /mnt/nbd/etc/shadow
echo "$SHADOW" | sudo tee -a /mnt/nbd/etc/shadow 
sync

# unmount the cloud image
sudo qemu-nbd -d /dev/nbd0

# convert the cloud image to raw format
qemu-img convert -f qcow2 -O raw focal-server-cloudimg-arm64.img focal-server-cloudimg-arm64.raw

# make an archive of the needed bits
tar -czvf focal-server-cloudimg-arm64.tgz *generic focal-server-cloudimg-arm64.raw

echo "scp the archive focal-server-cloudimg-arm64.tgz to your m1 mac for use"