Replace disk in the specified VM template in Proxmox with the given image.

qm-replace-disk

#!/bin/sh
# SPDX-FileCopyrightText: 2023 Jakub Jirutka <[email protected]>
# SPDX-License-Identifier: MIT
set -eu

PROGNAME='qm-replace-disk'
VERSION='0.1.0'

# Defaults
DISK='scsi0'

die() {
	printf "$PROGNAME: %s\n" "$@" >&2
	exit 2
}

help() {
	cat <<-EOF
	Usage: $PROGNAME [options] <vmid> <image>

	Replace disk in the specified VM template in Proxmox with the given image.

	Arguments:
	  <vmid>              ID of the VM template.
	  <image>             Path to the image file to import or "-" for stdin.

	Options:
	  -d --disk <diskid>  The disk to replace (default is "$DISK").
	  -V --version        Show script name & version and exit.
	  -h --help           Show this message and exit.
	EOF
}

parse_args() {
	local opts
	opts="$(getopt -n $PROGNAME -o d:hV -l disk:,help,version -- "$@")" || exit 1

	eval set -- "$opts"
	while [ $# -gt 0 ]; do
		case "$1" in
			-d | --disk) DISK=$2;;
			-h | --help) help; exit 0;;
			-V | --version) echo "$PROGNAME $VERSION"; exit 0;;
			--) shift; break;;
		esac
		shift 2
	done
	[ $# -eq 2 ] || die 'invalid number of arguments (try --help)'

	VMID=$1
	IMAGE_FILE=$2
}


parse_args "$@"

if [ "$(id -u)" -ne 0 ]; then
	echo 'Re-executing as root'
	exec sudo -u root "$0" "$@"
fi

config=$(qm config "$VMID") || exit 2

if ! echo "$config" | grep -qFx 'template: 1'; then
	die "VM $VMID is not a template!" >&2
fi

# Example: "scsi0: zfs_main:vm-1317-disk-1,iothread=1,size=5G".
storageid=$(echo "$config" | sed -En "s/^$DISK: ([^:]+).*/\1/p")
[ "$storageid" ] || die "VM $VMID does not have disk $DISK!"

diskopts="$(echo "$config" \
	| sed -En "s/^$DISK: [^,]+,?(.*)/\1/p" \
	| tr ',' '\n' \
	| grep -v '^size=' \
	| tr '\n' ',')"
diskopts="${diskopts%,}"

tmpfile=
if [ "$IMAGE_FILE" = '-' ]; then
	printf 'Reading image from stdin...'

	tmpfile="$(mktemp -t -p /var/tmp "$PROGNAME.XXXXXX")"
	IMAGE_FILE="$tmpfile"
	cat > "$tmpfile"

	size=$(stat -c %s "$IMAGE_FILE")
	echo " $(( $size >>20 )) MiB done." >&2
fi
[ -f "$IMAGE_FILE" ] || die "File $IMAGE_FILE does not exist or not readable!"

qm set "$VMID" -$DISK "$storageid:0,$diskopts,import-from=$IMAGE_FILE"
[ -f "$tmpfile" ] && rm "$tmpfile"

unused="$(qm config "$VMID" | grep -o '^unused[0-9]' | tail -n1)"
[ "$unused" ] && qm disk unlink "$VMID" --idlist "$unused"

exit 0