backup-automation/duplicati/duplicati-backup.sh

#!/bin/bash
SCRIPT_ABS_LOCATION=$(realpath "$(dirname "${0}")")

# shellcheck disable=SC1090
source "$SCRIPT_ABS_LOCATION/duplicati-backup.env"

# shellcheck disable=SC1090
source "$SCRIPT_ABS_LOCATION/../logger.sh"

# Default values
SOURCE_DIR="/mnt/data/duplicati"
MAX_BACKUPS=7
BACKUP_FOLDER=""
SSH_KEY="${SSH_KEY:-$HOME/.ssh/id_rsa}"

# shellcheck disable=SC2034
LOG_FILE="$SCRIPT_ABS_LOCATION/duplicati-backup.log"

# Override with command-line arguments
while getopts ":f:h:u:p:m:b:" opt; do
  case $opt in
    f) SOURCE_DIR="$OPTARG";;
    h) SSH_DESTINATION="$OPTARG";;
    u) SSH_USERNAME="$OPTARG";;
    p) SSH_KEY="$OPTARG";;
    m) MAX_BACKUPS="$OPTARG";;
    b) BACKUP_FOLDER="$OPTARG";;
    \?) echo "Invalid option: -$OPTARG"; exit 1;;
  esac
done

# Create a temporary file for the encrypted archive
TMP_FILENAME="duplicati_db-$(date +"%Y%m%d").bak"
TMP_FILEPATH="$SCRIPT_ABS_LOCATION"
if [ -z "$TMP_FILEPATH" ]; then
    log "Error: TMP_FILEPATH is not set."; exit 1
fi

# Create the encrypted archive using tar and openssl
log "Compressing and excrypting the Duplicati Databases"
sudo tar --absolute-names -czf - "$SOURCE_DIR" | openssl enc -aes-256-cbc -pbkdf2 -pass "pass:$BACKUP_ENCR_PASSPHRASE" > "$TMP_FILEPATH/$TMP_FILENAME" || { log "Error: Failed to create encrypted archive."; exit 1; }


# Connect to the backup host and count the number of existing backups
log "Fetching number of backups in destination folder"
EXISTING_BACKUPS=$(ssh "$SSH_USERNAME@$SSH_DESTINATION" -p 23 -i "$SSH_KEY" 'ls' | sudo wc -l) || { log "Error: Failed to count existing backups."; exit 1; }

# Remove old backups if there are too many
if (( EXISTING_BACKUPS > MAX_BACKUPS )); then
  log "Removing old backups in order to save space"
  ssh "$SSH_USERNAME@$SSH_DESTINATION" -p 23 -i "$SSH_KEY" "ls -t $BACKUP_FOLDER | tail -n +$((MAX_BACKUPS+1)) | xargs rm" || { log "Error: Failed to remove old backups."; exit 1; }
fi

# Transfer the encrypted archive to the backup host using scp
log "Transfering archive to SSH Destination"
scp -v -P 23 -i "$SSH_KEY" "$TMP_FILEPATH/$TMP_FILENAME" "$SSH_USERNAME@$SSH_DESTINATION:$BACKUP_FOLDER$TMP_FILENAME" || { log "Error: Failed to transfer the encrypted archive."; exit 1; }

# Remove the temporary file
log "Cleaning up files"
rm "$TMP_FILEPATH/$TMP_FILENAME" || { log "Error: Failed to remove the temporary file."; exit 1; }

log "Backup completed successfully."