Download cloudimage

ubuntu.conf

focal https://cloud-images.ubuntu.com/focal/current/ focal-server-cloudimg-amd64.img MD5SUMS
bionic https://cloud-images.ubuntu.com/bionic/current/ bionic-server-cloudimg-amd64.img MD5SUMS
xenial https://cloud-images.ubuntu.com/xenial/current/ xenial-server-cloudimg-amd64-disk1.img MD5SUMS

update.sh

#!/bin/bash

cd $(dirname $0)

if [ $# -lt 1 ]; then
	echo "update.sh <conf file>"
	exit 1
fi

conf=$1
echo $conf

if [ ! -e $conf ]; then
	echo "no $conf"
	exit 1
fi

IMGDIR=~/vm/images

check_and_download() {
	local suit=$1
	local url=$2
	local img=$3
	local chksum=$4
	echo $suit $url $img $chksum
	# get chksum
	curl -qLO $url/$chksum
	if [ $? -ne 0 ]; then
		echo "ERROR: $suit: download checksum"
		return
	fi
	if [ -e $chksum.$suit ]; then
		prevsum=$(cat $chksum.$suit)
		newsum=$(grep $img $chksum)
		if [ "$prevsum" == "$newsum" ]; then
			return
		fi
	fi
	# try to download the image
	curl -qLO $url/$img
	if [ $? -ne 0 ]; then
		echo "ERROR: $suit: download image"
		return
	fi
	# is there previous image?
	if [ -e $IMGDIR/$img ]; then
		rm -f $IMGDIR/$img.prev
		mv $IMGDIR/$img $IMGDIR/$img.prev
	fi
	mv $img $IMGDIR/$img
	grep $img $chksum > $chksum.$suit
}

while read l; do
	case "$l" in
	\#*)
		continue
	esac
	a=($l)
	check_and_download ${a[0]} ${a[1]} ${a[2]} ${a[3]}
done < $conf