sp-image-to-volume

#!/bin/sh
# SPDX-FileCopyrightText: 2017  StorPool <support@storpool.com>
# SPDX-License-Identifier: Apache-2.0

set -e

usage() {
	cat <<EOUSAGE
Usage:	sp-image-to-volume [-v] [-c client-command] image-name volume-name
	sp-image-to-volume -V | -h

	-c	specify the OpenStack client command to use (default: openstack)
	-h	display program usage information and exit
	-V	display program version information and exit
	-v	verbose operation; display diagnostic output
EOUSAGE
}

version() {
	echo 'sp-volume-to-image 0.1.0'
}

debug() {
	[ -z "$v" ] || echo "RDBG $*" 1>&2
}

unset hflag Vflag v
ocli='openstack'

while getopts 'c:hVv' o; do
	case "$o" in
		c)
			ocli="$OPTARG"
			;;

		h)
			hflag=1
			;;

		V)
			Vflag=1
			;;

		v)
			v='-v'
			;;

		*)
			usage 1>&2
			exit 1
			;;
	esac
done
[ -z "$Vflag" ] || version
[ -z "$hflag" ] || usage
[ -z "$Vflag$hflag" ] || exit 0

shift `expr "$OPTIND" - 1`
if [ "$#" -ne 2 ]; then
	usage 1>&2
	exit 1
fi

img_name="$1"
vol_name="$2"

# Get the image size and status
img_data="$($ocli image show -f json -- "$img_name" | jq -r '(.size | tostring) + ":" + .status')"
if [ -z "$img_data" ]; then
	echo "The '$img_name' image does not seem to exist" 1>&2
	exit 1
fi
img_size="${img_data%%:*}"
img_status="${img_data#*:}"
debug "got image size $img_size status $img_status"
if ! expr "x$img_size" : 'x[1-9][0-9]*$' > /dev/null; then
	echo "Could not obtain a numeric image size for the '$img_name' image, got '$img_size'" 1>&2
	exit 1
elif [ "$img_status" != 'active' ]; then
	echo "The '$img_name' image is not in the 'active' state, '$img_status' instead" 1>&2
	exit 1
fi

# Get the volume id and status
vol_data="$($ocli volume show -f json -- "$vol_name" | jq -r '.id + ":" + .status')"
if [ -z "$vol_data" ]; then
	echo "The '$vol_name' volume does not seem to exist" 1>&2
	exit 1
fi
vol_id="${vol_data%%:*}"
vol_status="${vol_data#*:}"
debug "got volume id $vol_id status $vol_status"
if [ "$vol_status" != 'available' ]; then
	echo "The '$vol_name' image is not in the 'available' state, '$vol_status' instead" 1>&2
	exit 1
fi

vol_sname="os--volume-$vol_id"
vol_ssize="$(storpool -Bj volume "$vol_sname" info | jq '.data.size')"
debug "got StorPool volume name $vol_sname size $vol_ssize"
if [ -z "$vol_ssize" ]; then
	echo "Could not obtain the size for the StorPool volume '$vol_ssname' for the '$vol_name' volume" 1>&2
	exit 1
elif ! expr "x$vol_ssize" : 'x[1-9][0-9]*$' > /dev/null; then
	echo "Could not obtain a numeric volume size for the '$vol_name' volume, got '$vol_ssize'" 1>&2
fi

vol_local="/dev/storpool/$vol_sname"
if [ -e "$vol_local" ]; then
	echo "The StorPool volume seems to be already attached here as $vol_local" 1>&2
	exit 1
fi

if [ "$vol_ssize" -ge "$img_size" ]; then
	debug "no need to resize the volume, it is big enough to hold the image"
else
	vol_nsize="$(echo "($img_size + 1024 * 1024 * 1024 - 1) / (1024 * 1024 * 1024)" | bc)"
	debug "resizing the volume to ${vol_nsize} GB"
	$ocli volume set --size "$vol_nsize" -- "$vol_name"
fi

# Prepare for creating a temporary file... yes, shell trap handling is a bit weird
unset img_temp cleanup_err

cleanup() {
	local res="$?"
	local arg="$1"

	if [ -n "$img_temp" ]; then
		rm -f -- "$img_temp"
		unset img_temp
	fi

	if [ "$arg" -eq 0 ] && [ -n "$res" ]; then
		arg="$res"
	fi
	: "${cleanup_err:=$arg}"
	exit $cleanup_err
}

trap 'cleanup 0' EXIT                                                                                                 
trap 'cleanup 2' QUIT TERM INT HUP

# Create a temporary file and store the image
img_temp="$(mktemp -t sp-image-to-volume.XXXXXX)"
trap "rm -f $v -- '$img_temp'" EXIT HUP INT QUIT TERM
debug "using a temporary image file $img_temp"
$ocli image save --file "$img_temp" -- "$img_name"
img_tsize="$(stat -c '%s' -- "$img_temp")"
debug "stored $img_tsize bytes there"
if [ "$img_tsize" != "$img_size" ]; then
	echo "Could not save the image to a temporary file, stored '$img_tsize' bytes, expected '$img_size' bytes" 1>&2
	exit 1
fi

debug "about to attach the $vol_sname volume here"
storpool -B attach volume "$vol_sname" here

debug "about to run 'qemu-img dd' to write the image contents to it"
qemu-img dd -O raw bs=1M if="$img_temp" of="$vol_local"

debug "about to detach the $vol_sname volume"
storpool -B detach volume "$vol_sname" here

debug 'all done'