quay/config_app/config_util/config/TransientDirectoryProvider.py

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)