tools.py 文件源码

def sign_gcs_url(gcs_filename, expires_after_seconds=6):
    """ cloudstorage signed url to download cloudstorage object without login
        Docs : https://cloud.google.com/storage/docs/access-control?hl=bg#Signed-URLs
        API : https://cloud.google.com/storage/docs/reference-methods?hl=bg#getobject
    """

    GCS_API_ACCESS_ENDPOINT = 'https://storage.googleapis.com'
    google_access_id = app_identity.get_service_account_name()
    method = 'GET'
    content_md5, content_type = None, None

    # expiration : number of seconds since epoch
    expiration_dt = datetime.utcnow() + timedelta(
        seconds=expires_after_seconds)
    expiration = int(time.mktime(expiration_dt.timetuple()))

    # Generate the string to sign.
    signature_string = '\n'.join([
        method,
        content_md5 or '',
        content_type or '',
        str(expiration),
        gcs_filename])

    signature_bytes = app_identity.sign_blob(str(signature_string))[1]

    # Set the right query parameters. we use a gae service account for the id
    query_params = {'GoogleAccessId': google_access_id,
                    'Expires': str(expiration),
                    'Signature': base64.b64encode(signature_bytes)}

    # Return the built URL.
    result = '{endpoint}{resource}?{querystring}'.format(
        endpoint=GCS_API_ACCESS_ENDPOINT,
        resource=gcs_filename,
        querystring=urllib.urlencode(query_params))
    return str(result)