import os from shutil import copytree from backports.tempfile import TemporaryDirectory from config_app.config_util.config.fileprovider import FileConfigProvider OLD_CONFIG_SUBDIR = 'old/' class TransientDirectoryProvider(FileConfigProvider): """ Implementation of the config provider that reads and writes the data from/to the file system, only using temporary directories, deleting old dirs and creating new ones as requested. """ def __init__(self, config_volume, yaml_filename, py_filename): # Create a temp directory that will be cleaned up when we change the config path # This should ensure we have no "pollution" of different configs: # no uploaded config should ever affect subsequent config modifications/creations temp_dir = TemporaryDirectory() self.temp_dir = temp_dir self.old_config_dir = None super(TransientDirectoryProvider, self).__init__(temp_dir.name, yaml_filename, py_filename) @property def provider_id(self): return 'transient' def new_config_dir(self): """ Update the path with a new temporary directory, deleting the old one in the process """ self.temp_dir.cleanup() temp_dir = TemporaryDirectory() self.config_volume = temp_dir.name self.temp_dir = temp_dir self.yaml_path = os.path.join(temp_dir.name, self.yaml_filename) def create_copy_of_config_dir(self): """ Create a directory to store loaded/populated configuration (for rollback if necessary) """ if self.old_config_dir is not None: self.old_config_dir.cleanup() temp_dir = TemporaryDirectory() self.old_config_dir = temp_dir # Python 2.7's shutil.copy() doesn't allow for copying to existing directories, # so when copying/reading to the old saved config, we have to talk to a subdirectory, # and use the shutil.copytree() function copytree(self.config_volume, os.path.join(temp_dir.name, OLD_CONFIG_SUBDIR)) def get_config_dir_path(self): return self.config_volume def get_old_config_dir(self): if self.old_config_dir is None: raise Exception('Cannot return a configuration that was no old configuration') return os.path.join(self.old_config_dir.name, OLD_CONFIG_SUBDIR)