Backup data to pwd/tar.gz from a container.

backup-docker.sh

#!/usr/bin/env bash
#
# $1: backup filename.
# $2: backup target dir.
# $3: backup target volumes

if [[ "$1" = "-h" ]]
  then
    echo '$1: backup filename.'
    echo '$2: backup target dir.'
    echo '$3: backup target volumes.'
    exit
fi

docker run --rm --volumes-from $3 -v $(pwd):/backup ubuntu tar cvf /backup/$1 $2