docker-volume

#!/usr/bin/env bash

USER_COMMAND=
USER_COMMAND_TARGETS=
BACKUP_DIRECTORY=
USE_FORCE=no
VOLUME_BACKUP_IMAGE_NAME=docker-volume-backup-helper
VOLUME_BACKUP_IMAGE_VERSION=1
VOLUME_BACKUP_IMAGE="$VOLUME_BACKUP_IMAGE_NAME:$VOLUME_BACKUP_IMAGE_VERSION"
PATH_TO_IMAGE_BUILD_DIR="/tmp/docker-volume-backup-helper-v$VOLUME_BACKUP_IMAGE_VERSION"
ARG_COUNTER=1

set $(getopt --path: "$@")
while [ $# -gt 0 ]
do
  case "$1" in
  backup|restore|clean)
    if [ "$ARG_COUNTER" = "1" ]; then
      USER_COMMAND="$1"
      if [ "$USER_COMMAND" = backup ]; then
        BACKUP_DIRECTORY=$(pwd)
      fi
    else
      echo ERROR first argument must be command, \'backup\' or \'restore\'
      exit 2
    fi
    ;;
  -f)
    USE_FORCE=yes
    ;;
  --path)
      if [ $USER_COMMAND = backup ]; then
        BACKUP_DIRECTORY="$(cd "$(dirname "$2")" ; pwd -P)/$(basename "$2")" # absolute path
        shift 1
      else
        echo "The --path key works only with backup command"
        exit 2
      fi
    ;;
  --help|-h)
    echo "This script saves content of docker volume to file.tar (BACKUP), "
    echo " and creates volume out of file.tar (RESTORE), created from the volume."
    echo "BACKUP usage: "
    echo "  docker-volume backup [--path PATH] [VOLUME...]"
    echo "    PATH    - directory for backups, \$PWD by default."
    echo "    VOLUMEs - names of docker volumes to be backed up in folder PATH, all volumes by default"
    echo "RESTORE usage: "
    echo "  docker-volume restore [-f] [FILE...|PATH...]"
    echo "    -f      - remove previous volume, prune containers if needed, interactive."
    echo "    PATHs   - directories of backups, where all *.tar files to be restored located."
    echo "    FILEs   - docker volume backups files *.tar, that were created by this script."
    exit 2
    ;;
  --version|-v)
      echo docker-volume version $VOLUME_BACKUP_IMAGE_VERSION
      exit 0
    ;;
  *)
    if [ "$ARG_COUNTER" = "1" ]; then
        echo ERROR invalid command \'"$1"\', only \'backup\' and \'restore\' alowed;
        exit 2
      else
        USER_COMMAND_TARGETS="$USER_COMMAND_TARGETS $1"
    fi
    ;;
  esac
  shift
  ARG_COUNTER=$((ARG_COUNTER + 1))
done

if [ "$ARG_COUNTER" = "1" ]; then
    echo "no arguments, use --help"
    exit 2
fi

function build_and_install_helper {
  # TODO check if dir creation permitted
  mkdir -p "$PATH_TO_IMAGE_BUILD_DIR"

  echo '
FROM alpine:latest
COPY --chmod=777 backup-volumes.sh /var/backup-volumes.sh
CMD sh /var/backup-volumes.sh
  ' > "$PATH_TO_IMAGE_BUILD_DIR"/Dockerfile

  echo '
#!/bin/env bash
if [ $COMMAND = BACKUP ]; then
	cd /var/src && tar -c ./ > /var/dst/"$VOLUME_NAME".tar
	exit $?
elif [ $COMMAND = RESTORE ]; then
	cd /var/dst/ && tar -xf /var/src/"$VOLUME_NAME".tar
	exit $?
else
	exit 1
fi
  ' > "$PATH_TO_IMAGE_BUILD_DIR"/backup-volumes.sh

  function clear_building_docker_backup_helper_image {
      rm "$PATH_TO_IMAGE_BUILD_DIR"/Dockerfile
      rm "$PATH_TO_IMAGE_BUILD_DIR"/backup-volumes.sh
      rmdir "$PATH_TO_IMAGE_BUILD_DIR"
  }

  docker build -t "$VOLUME_BACKUP_IMAGE_NAME:$VOLUME_BACKUP_IMAGE_VERSION" "$PATH_TO_IMAGE_BUILD_DIR"
  if [ $? -ne 0 ]; then
    echo ERROR cannot build helper image
    clear_building_docker_backup_helper_image
    exit 1
  fi

  clear_building_docker_backup_helper_image

  return $?
}

# check if docker available
docker --version > /dev/null

if [ $? -ne 0 ]; then
  echo ERROR docker is not available
  exit 1
fi

function contains {
  if [[ $1 =~ (^|[[:space:]])$2($|[[:space:]]) ]]; then
    return 0
  else
    return 1
  fi
}

VB_INSTALLED_IMAGE=$(docker images "$VOLUME_BACKUP_IMAGE_NAME" --format '{{.Repository}}:{{.Tag}}')

#if ! [[ "$VB_INSTALLED_IMAGE" =~ "$VOLUME_BACKUP_IMAGE" ]]; then
if ! contains "$VB_INSTALLED_IMAGE" "$VOLUME_BACKUP_IMAGE"; then
  # no helper image installed
  build_and_install_helper
fi

if [ "$USER_COMMAND" = backup ]; then
  mkdir -p "$BACKUP_DIRECTORY"
  if [ $? -ne 0 ]; then
    echo cannot access directory for backups
    exit 1
  fi

  EXISTING_VOLUMES=$(docker volume ls --format '{{.Name}}')
  if [ -z "$USER_COMMAND_TARGETS" ]; then
    USER_COMMAND_TARGETS="$EXISTING_VOLUMES"
  fi
  for VOLUME in $USER_COMMAND_TARGETS; do
    if contains "$EXISTING_VOLUMES" "$VOLUME"; then
      docker run -e COMMAND=BACKUP -e VOLUME_NAME="$VOLUME" -v "$VOLUME":/var/src --mount type=bind,source="$BACKUP_DIRECTORY",target=/var/dst/ "$VOLUME_BACKUP_IMAGE"
      if [ "$?" -ne "0" ]; then
        echo ERROR could not backup volume \'"$VOLUME"\'
      fi
    else
      echo ERROR volume \'"$VOLUME"\' was not found
    fi
  done
fi

function remove_volume_if_need_to_use_fore {
  local VOLUME_NAME="$1"
  if [ "$USE_FORCE" = "yes" ]; then
    docker volume rm $VOLUME_NAME
    if [ $? -ne 0 ]; then
      docker container prune
      docker volume rm $VOLUME_NAME
    fi
  else
    echo WARNING: volume \'"$VOLUME_NAME"\' exists, it will not be restored, delete it... or use the force
  fi
  return $?
}

function create_docker_volume_and_restore_data {
  local VOLUME_NAME="$1"
  local BACKUP_DIRECTORY="$2"
  docker volume create "$VOLUME_NAME" > /dev/null
  if [ $? -ne 0 ]; then
    echo ERROR could not create volume \'"$VOLUME_NAME"\'
    return 1
  fi

  docker run -e COMMAND=RESTORE -e VOLUME_NAME="$VOLUME_NAME" -v "$VOLUME_NAME":/var/dst --mount type=bind,source="$BACKUP_DIRECTORY",target=/var/src/ "$VOLUME_BACKUP_IMAGE"
  if [ $? -ne 0 ]; then
    echo ERROR could not run restoration for \'"$VOLUME_NAME"\'
    return 1
  fi
}

if [ "$USER_COMMAND" = restore ]; then
  EXISTING_VOLUMES=$(docker volume ls --format '{{.Name}}')
  for BACKED_FILE in $USER_COMMAND_TARGETS; do
    BACKED_FILE="$(cd "$(dirname "$BACKED_FILE")"; pwd -P)/$(basename "$BACKED_FILE")" # absolute path
    if [ -f $BACKED_FILE ]; then
      VOLUME_NAME=$(basename "$BACKED_FILE" | sed 's/\.tar$//')
      if contains "$EXISTING_VOLUMES" "$VOLUME_NAME"; then
        remove_volume_if_need_to_use_fore "$VOLUME_NAME"
      fi
      create_docker_volume_and_restore_data "$VOLUME_NAME" $(dirname "$BACKED_FILE")
    elif [ -d "$BACKED_FILE" ]; then
      VOLUMES=$(find "$BACKED_FILE" -name '*.tar')
      for VOLUME_NAME in $VOLUMES; do
        VOLUME_NAME=$(basename $VOLUME_NAME| sed 's/\.tar//')
        if contains "$EXISTING_VOLUMES" "$VOLUME_NAME"; then
          remove_volume_if_need_to_use_fore "$VOLUME_NAME"
        fi
        create_docker_volume_and_restore_data "$VOLUME_NAME" "$BACKED_FILE"
      done
    else
      echo ERROR tar-file or directory \'"$BACKED_FILE"\' does not exist
    fi
  done
fi

if [ "$USER_COMMAND" = clean ]; then
  docker image rm "$VOLUME_BACKUP_IMAGE"
  if [ $? -ne 0 ]; then
    docker container prune
    docker image rm "$VOLUME_BACKUP_IMAGE"
  fi
fi