datadb-scripts/get_backup

#!/usr/bin/env python3

import traceback
import os
from sys import exit,stdin,stdout
from os.path import join as pathjoin
from os.path import exists,getsize
from common.cgi import parse_qs,parse_auth,start_response
from common.datadb import DATADB_ROOT,DATADB_TMP


def get_backup_dir(backup_name):
    """
    Get the absolute local path to a backup or raise an exception if none exists
    :returns: str absolute path to backup seq /0/
    """
    backup_path = pathjoin(DATADB_ROOT, backup_name, 'data', '0', 'data')
    
    if not exists(backup_path):
        raise Exception("Backup does not exist")
    
    return backup_path


def handle_get_rsync(backup_name):
    """
    Prints the absolute path an rsync backup should pull from
    """
    backup_path = get_backup_dir(backup_name)
    
    start_response()
    print(backup_path+'/')


def handle_get_archive(backup_name):
    """
    Returns .tar.gz data to the browser
    """
    backup_path = pathjoin(get_backup_dir(backup_name), 'backup.tar.gz')
    
    with open(backup_path, 'rb') as f:
        start_response(content_type="application/x-gzip", extra_headers=["Content-length: %s" % getsize(backup_path),
                                                                         "Content-Disposition: attachment; filename=\"backup.tar.gz\""])
        while True:
            data = f.read(8192)
            if not data:
                break
            stdout.buffer.write(data)
    exit(0)


def handle_req():
    """
    Parse http query parameters and act accordingly.
    """
    params = parse_qs()
    
    for param_name in ["proto", "name"]:
        if not param_name in params:
            raise Exception("Missing parameter: %s" % param_name)
    
    if os.environ['REQUEST_METHOD'] == "GET" and params["proto"] == "rsync":
        # Should return absolute local path to latest backup dir
        handle_get_rsync(params["name"])
    
    elif os.environ['REQUEST_METHOD'] == "GET" and params["proto"] == "archive":
        # Should respond by transferring tar.gz data
        handle_get_archive(params["name"])
    
    else:
        raise Exception("Invalid request. Params: %s" % params)


if __name__ == "__main__":
    try:
        handle_req()
    except Exception as e:
        start_response(status_code=("500", "Internal server error"))
        
        tb = traceback.format_exc()
        print(tb)