Docker Named Volume Backup tool

dockerbackup.sh

#!/bin/bash

action=$1 #Backup or restore
volume_name=$2 #The name of the docker-compose volume to restore or backup.
output_dir=$3 #Where to read from (if restore) or to write to (if backup) the backup.
file_name=$4 #How the backup is (if restore) or will (if backup) be named.

function usage() {
  echo "Usage: db (backup|restore) volume_name output_input_dir file_name"
  exit
}

function backup() {
    docker run --rm -v $volume_name:/tmpvolume -v $output_dir:/tmpbackup alpine tar cf /tmpbackup/$file_name.tar /tmpvolume
}

function restore() {
    docker run --rm -v $volume_name:/tmpbackup -v $output_dir:/tmpvolume alpine tar xf /tmpvolume/$file_name.tar -C /tmpbackup --strip 1
}

if [ $# -ne 4 ]; then
    usage
fi

case "$action" in
"backup" )
backup
;;
"restore" )
restore
;;
* )
usage
;;
esac