code: def read(alias_name, allow_none=False):
      
      warnings.warn('Will be removed in v1.0', DeprecationWarning, stacklevel=2)
      return core.read('{0}_PORT'.format(alias_name), default=None, allow_none=allow_none)
docs: Get the raw docker link value.
  
      Get the raw environment variable for the docker link
  
      Args:
          alias_name: The environment variable name
          default: The default value if the link isn't available
          allow_none: If the return value can be `None` (i.e. optional)