Move a libvirt VM from one host to another

virsh_offline_vm_xfer.sh

#!/bin/bash
#
# Usage: ./virsh_offline_vm_xfer.sh <domain> <host>
#
# Requirements
#  1. The same user on the local and remote machine that are able to sudo
#  2. Both normal users belong to the libvirt group respectively or have
#     global libvirtd access. (can access qemu:///system)
#  3. Assumes image paths can remain identical during transfer
#
# Author: Michael Goodwin Date: 2017-05-12

trap 'breakdown "$HOST"' EXIT SIGINT SIGQUIT SIGTERM

DOMAIN="$1"
HOST="$2"
LOCAL_LIBVIRT_URI="qemu:///system"
REMOTE_LIBVIRT_URI="qemu+ssh://${HOST}/system"
IMAGES_PATH="/var/lib/libvirt/images"
SUDOERS_PATH="/etc/sudoers.d/vmxfer_nopasswd"
CMD="/usr/bin/rsync"

push() {

	virsh_xfer_xml() {
		local domain="$1"
		virsh -c "${LOCAL_LIBVIRT_URI}" dumpxml --migratable "$domain" \
			| virsh -c "${REMOTE_LIBVIRT_URI}" define /dev/stdin
	}

	get_image_path() {
		local domain="$1"
		virsh -c "${LOCAL_LIBVIRT_URI}" domblklist --details "$domain" \
			| awk '$1 == "file" && $2 == "disk" { print $NF }'
	}

	xfer_vm_image() {
		local domain="$1" host="$2" path
		get_image_path "$domain" | while read -r path; do
			if [[ "$path" =~ ^/dev/mapper ]]; then
				{ echo "Block devices not supported!"; exit 1; }
			else
				sudo rsync -aAXWPS --rsync-path='sudo rsync' \
					"$path" "${USER}@${host}:${IMAGES_PATH}"
			fi
		done
	}

	setup_sudo_nopasswd() {
		local host="$1" cmd
		cmd="$( sed 's|"||g' <<< "$CMD" )"
		sudoers_docu=$(
			cat <<-EOF
				${USER} ALL=(root) NOPASSWD: ${cmd}
			 	${USER} ALL=(root) NOPASSWD: /bin/rm -v ${SUDOERS_PATH}
			EOF
		)

		if echo "${sudoers_docu}" | visudo -cf-; then
			#
			mkscript() {
				base64 <<-EOF
					#!/bin/sh
					echo '${sudoers_docu}' > "${SUDOERS_PATH}"
					if ! visudo -cf "${SUDOERS_PATH}"; then
						rm -v "${SUDOERS_PATH}"
					else
						exit 1
					fi
				EOF
			}

			# Places remote sudoers file for tar
			remote_temp=$(
				ssh -q "${USER}@${host}" -- '
				tempfile=$(mktemp)
				base64 -d > "$tempfile"
				echo "$tempfile"' < <(mkscript)
			)
			# Reads pw from tty to actually use sudo to
			# execute the temporary sudoers script
			ssh -tq "${USER}@${host}" -- "\
				sudo -- bash \"${remote_temp}\"
				rm \"${remote_temp}\""
		else
			exit 1
		fi
	}

	"$@"
}

breakdown() {
	local host="$1"
	ssh -q "${USER}@${host}" -- sudo -n -- "/bin/rm -v ${SUDOERS_PATH}"
}


push setup_sudo_nopasswd "$HOST" \
&& push xfer_vm_image "$DOMAIN" "$HOST" \
&& push virsh_xfer_xml "$DOMAIN" \