text: # Copyright 2016-2020, Pulumi Corporation.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  import typing
  
  
  def get_image_name_and_tag(base_image_name: str) -> typing.Tuple[str, typing.Optional[str]]:
      # From https://docs.docker.com/engine/reference/commandline/tag
      #
      # "A tag name must be valid ASCII and may contain lowercase and uppercase letters, digits,
      # underscores, periods and dashes. A tag name may not start with a period or a dash and may
      # contain a maximum of 128 characters."
      #
      # So it is safe for us to just look for the colon, and consume whatever follows as the tag
      # for the image.
  
      try:
          last_colon = base_image_name.index(":")
          return base_image_name[0: last_colon], base_image_name[last_colon + 1:]
      except ValueError:
          return base_image_name, None
  