#!/bin/bash
# https://github.com/spherex-dev/docker-backup-volume
# creates a docker volume from a backup

while [ $# -gt 0 ]; do
  case "$1" in
    -v|-volume|--volume)
      volume="$2"
      ;;
    -p|-prefix|--prefix)
      prefix="$2"
      ;;
    -n|-volume-name|--volume-name)
      volume_name="$2"
      ;;
    -s|-snapshot|--snapshot)
      snapshot="$2"
      ;;
    -h|-help|--help)
      printf "--volume the backup name of the volume\n"
      printf "--volume-name (optional) create the backup as this volume name\n"
      printf "--prefix the storage prefix of the backup location"
      exit 1
      ;;
    *)
      printf "***************************\n"
      printf "* Error: Invalid argument.*\n"
      printf "***************************\n"
      exit 1
  esac
  shift
  shift
done

if [ -z "$volume_name" ]; then
  volume_name=$volume
fi

volume_exists=$(docker volume ls | grep -q $volume_name)
if [ $volume_exists ]; then
  printf "***********************************\n"
  printf "Error: volume $volume_name exists. \n"
  printf "Please delete before proceeding    \n"
  printf "***********************************\n"
  exit 1
fi

if [ -z "$snapshot" ]; then
  snapshot=$(ls -At ${prefix}/${volume}/ | tail -n 1)
fi

if [ -z "$snapshot" ]; then
  printf "**********************************\n"
  printf "* Error: Unable to find snapshot.*\n"
  printf "**********************************\n"
  exit 1
else
  echo "creating from snapshot: ${snapshot}"
fi

uuid=$(cat /proc/sys/kernel/random/uuid)
cwd=$(pwd)

IMAGE=alpine:latest
docker run \
--mount "type=volume,src=${volume_name},dst=/data" \
--name $uuid \
$IMAGE

mkdir /tmp/$uuid
tar -xf $prefix/$volume/$snapshot -C /tmp/$uuid 
cd /tmp/$uuid

docker cp -a . $uuid:/data
docker rm $uuid
cd $cwd