Python files/folders zip and backup

backup_zip.py

import time
import os
import glob
import shutil
import zipfile

thetime = time.strftime("%Y-%m-%d-%H-%M")
numdays = 86400*14
now = time.time()
FOLDER_PATH = "path/to/your/data"
BACKUP_DIR = "path/to/backup"
dir_name = "some_name" + "_" + thetime

def log(string):
    path = BACKUP_DIR + '\\backup.log'
    with open(path,'a') as log_file:
        log_file.write(time.strftime("%Y-%m-%d-%H-%M-%S", time.gmtime()) + ": " + str(string) + '\n')
        log_file.close()

def zip_folder(folder_path, output_path):
    """Zip the contents of an entire folder (with that folder included
    in the archive). Empty subfolders will be included in the archive
    as well.
    """
    parent_folder = os.path.dirname(folder_path)
    # Retrieve the paths of the folder contents.
    contents = os.walk(folder_path)
    try:
        zip_file = zipfile.ZipFile(output_path, 'w', zipfile.ZIP_DEFLATED)
        for root, folders, files in contents:
            # Include all subfolders, including empty ones.
            for folder_name in folders:
                absolute_path = os.path.join(root, folder_name)
                relative_path = absolute_path.replace(parent_folder + '\\',
                                                      '')
                zip_file.write(absolute_path, relative_path)
            for file_name in files:
                absolute_path = os.path.join(root, file_name)
                relative_path = absolute_path.replace(parent_folder + '\\',
                                                      '')
                zip_file.write(absolute_path, relative_path)
    except IOError as message:
        log(message)
        sys.exit(1)
    except OSError as message:
        log(message)
        sys.exit(1)
    except zipfile.BadZipfile as message:
        log(message)
        sys.exit(1)
    finally:
        zip_file.close()

# Delete old backup files first.
directory=os.path.join(BACKUP_DIR)
for r,d,f in os.walk(directory):
    for dir in d:
         timestamp = os.path.getmtime(os.path.join(r,dir))
         if now-numdays > timestamp:
             try:
                  log("removing" ,os.path.join(r,dir))
                  shutil.rmtree(os.path.join(r,dir))
             except Exception as e:
                  log(e)
                  pass
             else:
                  log("Backup files older than %s were deleted." % time.strftime('%c', time.gmtime(numdays)))

# Backup  data dirs
log("Copying started...")
shutil.copytree(FOLDER_PATH, BACKUP_DIR + dir_name)
log("Copying finished...")

log("Compressing started...")
zip_folder(BACKUP_DIR + internal_dir_name, dir_name + '.zip')
log("Compressing finished...")
shutil.rmtree(dir_name)

log("Backup job complete.")