Configure brakeman (ruby linter) to only lint current file/buffer?

Is there a way to configure the brakeman linter to only lint the current file or buffer?
I am aware of `g:ale_ruby_brakeman_options` and know that there is a `--only-files` option for brakeman, so theoretically it should be possible.
But I have no clue how to refer to the current buffer and/or file in the variable definition, if it is possible at all.
Can someone help me? And if that is not possible, then I'd propose this as a new feature.