Converts rdiff-backup backups to Borg Backup.

rdiff-backup-to-borg.sh

#!/bin/bash
# rdiff-backup-to-borg
# Converts rdiff-backup backups to Borg Backup
#
# This script was created to ease switching from `rdiff-backup` to `borg`. It
# restores all increments of a rdiff-backup repository and backs it up using
# Borg Backup.
#
# More info about Borg Backup: <https://borgbackup.readthedocs.io>
# More info about rdiff-backup: <https://rdiff-backup.net/>
#
# Copyright (C) 2023 Daniel Rudolf (<https://www.daniel-rudolf.de>)
# License: The MIT License <http://opensource.org/licenses/MIT>
#
# SPDX-License-Identifier: MIT

export LC_ALL=C

print_usage() {
    echo "Usage:"
    echo "  $(basename "$0") <BORG_REPOSITORY> <RDIFF_REPOSITORY>..."
    echo "  $(basename "$0") --list <RDIFF_REPOSITORY>..."
}

# parse parameters
BORG_BACKUP=
BACKUP_PREFIX=
LIST_ACTION=

while [ $# -gt 0 ]; do
    if [ "$1" == "--help" ]; then
        print_usage
        exit 0
    elif [ "$1" == "-l" ] || [ "$1" == "--list" ]; then
        LIST_ACTION="y"
        shift

        break
    elif [ "$1" == "-p" ] || [ "$1" == "--prefix" ]; then
        if [ -z "${2:-}" ]; then
            echo "Missing required value for option '--prefix'" >&2
            exit 1
        fi

        BACKUP_PREFIX="$2-"
        shift 2
    elif [ -z "$BORG_BACKUP" ]; then
        BORG_BACKUP="$1"
        shift

        break
    fi
done

# list rdiff-backup increments
if [ -n "$LIST_ACTION" ]; then
    INDEX=0
    for REPO in "$@"; do
        REPO_NAME="$(basename "$REPO")"

        while read -r BACKUP; do
            [ -z "$BACKUP" ] || echo "$((++INDEX))    $REPO_NAME    $BACKUP"
        done <<< "$(rdiff-backup -l "$REPO" \
            | sed -ne 's/^    increments\.\(.*\)\.dir  .*$/\1/p')"

        BACKUP_CURRENT="$(basename "$REPO/rdiff-backup-data/current_mirror."*".data")"
        BACKUP_CURRENT="${BACKUP_CURRENT:15:-5}"
        echo "$((++INDEX))    $REPO_NAME    $BACKUP_CURRENT (latest)"
    done

    exit
fi

# add rdiff-backup increments to Borg repository
if [ -z "$BORG_BACKUP" ]; then
    print_usage >&2
    exit 1
fi

if [ -e "$BORG_BACKUP" ]; then
    if [ ! -d "$BORG_BACKUP" ]; then
        echo "Invalid Borg repository '$BORG_BACKUP': Not a directory" >&2
        exit 1
    elif ! grep -qF "Borg Backup repository" "$BORG_BACKUP/README" 2> /dev/null; then
        echo "Invalid Borg repository '$BORG_BACKUP': Not a Borg repository" >&2
        exit 1
    fi
else
    echo "Creating Borg repository..."
    mkdir "$BORG_BACKUP"
    borg init --encryption=repokey "$BORG_BACKUP"
    echo
fi

RESTORE="$(mktemp -d)"
trap "rm -rf ${RESTORE@Q}" ERR EXIT

OLD_PWD="$PWD"
for REPO in "$@"; do
    echo "################################################################################"
    echo "Accessing rdiff-backup repository '$REPO'..."

    BACKUP_INFO="$(rdiff-backup -l "$REPO")"
    BACKUP_COUNT="$(sed -ne '1 s/^Found \([0-9]*\) increments:$/\1/p' <<< "$BACKUP_INFO")"
    ((BACKUP_COUNT++))

    echo "Found $BACKUP_COUNT rdiff-backup snapshot(s):"

    BACKUPS=()
    if (( "$BACKUP_COUNT" > 1 )); then
        readarray -t BACKUPS <<< "$(sed -ne 's/^    increments\.\(.*\)\.dir  .*$/\1/p' <<< "$BACKUP_INFO")"
        printf -- '- %s\n' "${BACKUPS[@]}"
    fi

    BACKUP_CURRENT="$(basename "$REPO/rdiff-backup-data/current_mirror."*".data")"
    BACKUP_CURRENT="${BACKUP_CURRENT:15:-5}"
    BACKUPS+=( "$BACKUP_CURRENT" )
    printf -- '- %s (latest)\n' "$BACKUP_CURRENT"

    BACKUP_INDEX="$((BACKUP_COUNT - 1))"
    for BACKUP in "${BACKUPS[@]}"; do
        echo

        echo "Restoring rdiff-backup snapshot '$BACKUP' (#$BACKUP_INDEX)..."
        rdiff-backup -r "${BACKUP_INDEX}B" \
            --exclude-sockets \
            "$REPO" \
            "$RESTORE/$BACKUP"

        echo "Creating Borg backup of '$BACKUP'..."
        cd "$RESTORE/$BACKUP"
        borg create -v --stats --show-rc --progress --compression=lz4 \
            --timestamp="$(date -d "$BACKUP" -u +'%Y-%m-%dT%H:%M:%S')" \
            --comment="rdiff-backup" \
            "$BORG_BACKUP"::"$BACKUP_PREFIX$BACKUP" \
            .

        echo "Removing rdiff-backup snapshot '$BACKUP'..."
        cd "$OLD_PWD"
        rm -rf "$RESTORE/$BACKUP"

        ((BACKUP_INDEX--))
    done

    echo
done