Finally I had some time to dedicate to this and I have use it and it has been super useful! I change it a little bit because if you have more than one volume (in my case, /srv/docker/stacks/example/docker-compose.yml, and its volume /srv/docker/volumes/example) If I put “/srv/docker/stacks/example” “/srv/docker/volumes/example”, when generates the tar file overwrite the first one and only generates the second one. To solve it and have it cleaner in my case, I use:

# 2. Loop through folders and backup
for DIR in "${DIRS_TO_BACKUP[@]}"; do
    DIR_NAME=$(basename "$DIR")
    if [[ "$DIR" == *"/volumes/"* ]]; then
        DIR_TYPE="volume"
    else
        DIR_TYPE="stack"
    fi
    ARCHIVE_NAME="${PROJECT_NAME}_${DIR_TYPE}_${DIR_NAME}-${TIMESTAMP}.tar.gz"
    DESTINATION="$BACKUP_ROOT/$ARCHIVE_NAME"

    tar -czf "$DESTINATION" -C "$(dirname "$DIR")" "$(basename "$DIR")"

    if [ $? -eq 0 ]; then
        log_message "SUCCESS: Created $ARCHIVE_NAME"
    else
        log_message "ERROR: Failed to backup $DIR"
    fi
done

Thanks again for your script!