dvbackup/dvbackup.sh

#!/usr/bin/env sh

if [ -z "$DOCKER" ]; then
    DOCKER=docker
fi


echo_and_run() {
    echo "$@"
    "$@"
    return $?
}

backup() {
    volume="$1"
    target="$(realpath "$2")"
    target_dir="$(dirname "$target")"
    target_name="$(basename "$target")"

    test -z "$("$DOCKER" volume ls | grep "$volume")" && { echo "Error: No such volume, aborting" >&2; exit 1; }
    test -z "$target_dir" && { echo "Error: No base folder found for target=$target" >&2; exit 2; }
    test -z "$target_name" && { echo "Error: No target name found for target=$target" >&2; exit 3; }

    "$DOCKER" run --rm \
        --mount="type=volume,source=$volume,destination=/data,ro=true" \
        --mount="type=bind,source=$target_dir,destination=/data2" \
        busybox /bin/sh -c \
        "cd /data/ && tar cf '/data2/$target_name' ./* && chown $(id -u):$(id -g) /data2/$target_name"
}

restore() {
    target="$(realpath "$1")"
    target_dir="$(dirname "$target")"
    target_name="$(basename "$target")"
    volume="$2"

    test -z "$("$DOCKER" volume ls | grep "$volume")" && { echo "Error: No such volume, aborting" >&2; exit 1; }
    test -z "$target_dir" && { echo "Error: No base folder found for target=$target" >&2; exit 2; }
    test -z "$target_name" && { echo "Error: No target name found for target=$target" >&2; exit 3; }

    set -x
    "$DOCKER" run --rm \
        --mount="type=volume,source=$volume,destination=/data" \
        --mount="type=bind,source=$target_dir,destination=/data2" \
        busybox /bin/sh -c \
        "cd /data/ && rm -rf ./* && tar xf '/data2/$target_name'"
    set +x
}

backup_all() {
    "$DOCKER" volume ls \
            | awk '!/^[a-z]+ +[0-9a-f]+$/ && (NR>1) {print $2}' \
            | while read -r volume_name; do
        echo "$volume_name -> $volume_name.tar"
        backup "$volume_name" "$volume_name.tar"
    done
}

restore_all() {
    for tarball in "$@"; do
        volume_name="${tarball%.tar}"
        echo "$volume_name -> $volume"
        if ! "$DOCKER" volume inspect "$volume_name" 1>&2 2>/dev/null; then
            echo "Error: no such volume $volume_name" >&2
            exit 4
        fi
        restore "$tarball" "$volume_name"
    done
}

"$@"