Bash to create external snapshot. Inspired by https://blog.programster.org/kvm-external-snapshots

external_snapshot.sh

#!/bin/bash

set -o xtrace
set -o errexit

DOMAIN=${1:-$VM}
if [ -z "${DOMAIN}" ]; then
    DOMAIN="$(basename $PWD)_default"
fi

# Check that we got a valid DOMAIN
virsh dominfo $DOMAIN >/dev/null || exit 1

TIMESTAMP=$(date +%s)
SNAPSHOT_NAME=$TIMESTAMP

VM_FOLDER="${PWD}/.vagrant"
[ -d "${VM_FOLDER}/machines/default" ] || { echo 'Dont see expected VM_folder. Bailing...' >&2; exit 1; }

SNAPSHOT_FOLDER="${VM_FOLDER}/snapshots/${DOMAIN}/${TIMESTAMP}"
mkdir -pv ${SNAPSHOT_FOLDER} | tail -1

MEM_FILE="${SNAPSHOT_FOLDER}/mem.qcow2"
DISK_FILE="${SNAPSHOT_FOLDER}/disk.qcow2"

# Find out if running or not
STATE=$(virsh domstate ${DOMAIN} 2>/dev/null | grep -q running && echo running ||:)

if [ "$STATE" = "running" ]; then

  virsh snapshot-create-as \
    --domain $DOMAIN $SNAPSHOT_NAME \
    --diskspec vda,file=$DISK_FILE,snapshot=external \
    --memspec file=$MEM_FILE,snapshot=external \
    --atomic

else

  virsh snapshot-create-as \
    --domain $DOMAIN $SNAPSHOT_NAME \
    --diskspec vda,file=$DISK_FILE,snapshot=external \
    --disk-only \
    --atomic

fi
echo ok